EP1435265A2 - Apparatus for spraying liquids, and disposable containers and liners suitable for use therewith - Google Patents

Abstract

A reservoir (40) for a gravity feed spray gun comprises a container (41)and a removable lid (42) arranged to close an opening in the container(41) and provided with an outlet for transferring liquid from the reservoir(40) to an inlet of the spray gun during operation of the spray gun. Abase of the container (41) is provided with an air hole (44) that can beclosed when required. The reservoir (40) is provided with a filter (45)arranged to filter liquid withdrawn from the reservoir (40) through theoutlet in the lid (42). The filter (45) may be located in the lid (42) and arange of filters (45) having different mesh sizes is provided for selectionof a suitable mesh size. The lid (42) is detachable from the container(41) and may be releasably secured (41) by screw fit or push fit or by ascrew-on collar.

Description

• The present invention relates to containers, more especially, disposable containersand to containers which can function as liners. The invention also relates toapparatus for spraying liquids (for example, spray guns) and, more especially, to theliquid containers or reservoirs of such apparatus.
• There are many uses, in many different fields, for disposable containers. Forexample, many goods are packaged in disposable containers (e.g. bags) eitherbefore or after purchase. When the disposable container is a plastic bag, it willoften be re-used by the purchaser as a disposable liner for another receptacle, forexample a refuse bin. In some cases, disposable liners are produced specifically foruse in other, re-usable, receptacles: in those cases, the liner may be intended to aiddisposal of the contents of the receptacle (as in the case of a liner in a refuse bin); toprotect the receptacle or its contents; or to facilitate, or even eliminate, the cleaningof the receptacle.
• The use of a liner in a receptacle in which a substance like glue, paint or plaster ismixed or contained for use can be particularly advantageous, in terms of facilitatingthe cleaning of the receptacle after use and of preventing substances in thereceptacle from being contaminated by the remains of other substances.Receptacles in which paints are mixed or contained for use, for example, must beclean to ensure that the colour or quality of the paint is not altered by traces ofother substances: that is particularly important, as explained above, when a vehicleis being re-painted and the paint is required to match an existing one. To avoidcontamination problems when mixing paints, it is often the practice in vehicle bodyshops to use disposable waxed paper cups as mixing containers, particularly whenonly a small amount of paint is required. An alternative approach, proposed in US-A-4 383 635, involves the provision of a disposable container which, for use, islocated in a re-usable frame-like receptacle.
• In the field of spray guns, it has been proposed for various reasons that a disposableliner should be used in the reservoir of the gun (see US-A-3 211324, 3 255 972,4 151 929, 4 951 875 and 5143 294, and EP-A-0 678 334). Guns for sprayingliquids (eg. paints, garden chemicals etc.) are generally well known and typicallycomprise a reservoir in which a liquid to be dispensed is contained, and a spraynozzle through which the liquid is dispensed, under pressure, under the control of atrigger mechanism. The liquid may be fed from the reservoir under gravity and/or itmay be entrained in a stream of pressurized fluid, for example air or water, which issupplied to the gun from an external source.
• When a user wishes to change the liquid in the reservoir of a spray gun, it is usuallynecessary to clean the gun very thoroughly to ensure that no traces of the old liquidremain in the gun to contaminate the new liquid. That applies particularly to paintspray guns because any traces of an old batch of paint remaining in a gun may affectthe colour of a new batch of paint to the extent that the new batch of paint becomesuseless. This can cause problems especially in vehicle body shops where the paintapplied to a vehicle is often required to match existing paint work exactly.Alternatively, if paint residues have been allowed to dry within the gun, they mayflake and contaminate the new batch of paint. The cleaning of spray guns is,however, a comparatively complex and time consuming operation. Moreover, inthe case of paint spray guns, the cleaning operation involves the use ofcomparatively large amounts of solvents which, for environmental reasons, shouldbe handled and disposed of with care. That, in turn, can add substantially to thecost of a painting operation. It has already been suggested (see, for example,EP-A-0 678 334 mentioned above) that the use of a disposable liner in the paintreservoir (i.e. the paint pot) of a spray gun can simplify the cleaning of the gun andreduce the amount of solvent required.
• The present invention is concerned with the provision of a container which issufficiently inexpensive to be disposable and which can preferably be collapsedwhen it is to be disposed of but which, nevertheless, is comparatively easy to handleand to fill when in use. The invention is concerned, more especially, with theprovision of such a container which is suitable for use as a finer in anotherreceptacle. The present invention is also concerned with enabling the cleaning ofspray guns and like apparatus to be simplified, and with thereby enabling the timeand expense associated with that operation to be reduced.
• The present invention provides a container comprising side walls and acomparatively-rigid base thermo/vacuum-formed from a plastics material; whereinthe side walls are thin in comparison to the base and are collapsible, but thecontainer is capable of standing, unsupported, on the base with the side wallsextended and upright.
• More especially, the present invention provides a container comprising a base, andside walls extending from the base; wherein the base and side walls arethermo/vacuum formed together from a plastics material in such a manner that thebase is comparatively rigid and the side walls are thin in comparison to the base andare collapsible but the container is capable of standing unsupported, on the basewith the side walls extended and upright.
• A container in accordance with the invention may be used as a liner for a receptacle,the liner having a shape which corresponds to the interior of the receptacle. As amodification, the invention also provides, in combination with a receptacle, adisposable liner which fits within and has a shape corresponding to the interior ofthe receptacle wherein the liner is thermo/vacuum formed from a plastics material.The liner is preferably, but not necessarily, collapsible.
• The present invention also provides a spray gun comprising a fluid reservoir, aremovable, collapsible, liner which has a shape corresponding to, and is a close fit within, the interior of the reservoir, and a spray nozzle for dispensing fluid fromwithin the liner, wherein the liner collapses when fluid is withdrawn from within theliner during operation of the gun.
• Also in accordance with the invention, there is provided a spray gun comprising afluid reservoir having a removable lid located in an opening in the reservoir; aremovable liner located within the reservoir and secured to the reservoir, by the lid,at the periphery of the opening; and a spray nozzle for dispensing fluid from withinthe liner; wherein the liner is removable from the reservoir together with the lid.
• The present invention also provides a gravity-fed spray gun comprising a fluidreservoir having a removable lid located in an opening in the reservoir; and a spraynozzle for dispensing fluid drawn from within the reservoir through an outlet in thelid; wherein the reservoir is removable from the gun and is capable of standing onits own to enable fluid to be loaded into the reservoir through the opening.
• The invention further provides a spray gun comprising a fluid reservoir; and a spraynozzle for dispensing fluid from within the reservoir; the reservoir comprising a self-supportingcontainer which is removable from the gun and is collapsible fordisposal.
• In accordance with another aspect of the invention, there is provided a fluidreservoir for attachment to a spray gun, the reservoir having a removable lid whichis located in an opening in the reservoir and in which is formed a fluid outlet for thereservoir; the reservoir including a removable, collapsible, liner which has a shapecorresponding to, and is a close fit within, the reservoir, wherein the liner is securedto the reservoir by the lid at the periphery of the opening and is removable from thereservoir together with the lid. The invention also provides a fluid reservoir forattachment to a spray gun, the reservoir having a removable lid which is located inan opening in the reservoir and in which is formed a fluid outlet for the reservoir, the fluid outlet being shaped for attachment to the spray gun; and a closable air ventin the end of the reservoir remote from the lid.
• In accordance with yet another aspect of the invention, there is provided a liner foruse in the reservoir of a spray gun, the liner being formed from a plastic materialand being a close fit within the reservoir; the liner having a comparatively rigid base,and side walls which are thin in comparison to the base and are collapsible.
• The present invention also provides a spray gun comprising a fluid reservoir, and aspray nozzle for dispensing fluid from within the reservoir, the reservoir having aremovable lid and including a removable, generally conical, mesh filter secured inthe reservoir by the lid.
• The present invention also provides a gravity-feed spray gun comprising a fluidreservoir, and a spray nozzle for dispersing fluid from within the reservoir, thereservoir having a removable lid and a removable liner secured in the reservoir bythe lid.
• The term "thermo/vacuum-forming" as used herein means a process by which asheet of material is heated to a softened condition and formed into a required shape,defined by a mould, while in that softened condition. It includes the case in whichthe application of a differential air pressure is used to assist in forming the materialinto the required shape and, in particular, includes the case in which a vacuum isproduced on one side of the material to assist in forming it into the required shape(also known simply as ''vacuum-forming").
• The term "collapsible" as used herein with reference to the side walls of acontainer/liner in accordance with the invention indicates that the side walls can bedistorted so that, by the application of moderate pressure (e.g. hand pressure), therim of the container can be pushed towards the base of the container, without theside walls being ruptured.
• The term "paint" is used herein to include all forms of paint-like coating materialsthat can be applied to a surface using a spray gun, whether or not they are intendedto colour the surface. The term includes, for example, primers, base coats, lacquersand similar materials.
• By way of example only, embodiments of the invention will be described withreference to the accompanying drawings. in which:
• Fig. 1 is a perspective view of a prior art spray gun, shown partly-disassembled sothat it can be filled with paint;
• Fig. 2 shows the components of an alternative form of paint reservoir for the gun ofFig. 1, in an exploded condition;
• Fig. 3 shows the paint reservoir of Fig. 2 in an assembled condition, with an adapterfor connecting the reservoir to a spray gun;
• Fig. 4 shows a longitudinal cross-section through the paint reservoir and the adapterof Fig. 3;
• Fig. 5 shows the paint reservoir of Fig. 4 being attached to a spray gun;
• Fig. 6 shows the paint reservoir of Fig. 4 in use on a spray gun;
• Fig. 7 shows components of the paint reservoir of Fig. 4 being removed after use;
• Fig. 8 is similar to Fig. 2 but shows a modified form of paint reservoir;
• Fig. 9 shows a longitudinal cross-section through an alternative form of lid for thepaint reservoirs of Figs. 2 to 4 and 8;
• Fig. 10 is similar to Fig. 2 but shows another modified form of paint reservoir;
• Fig. 11 shows part of a longitudinal cross-section through the paint reservoir of Fig.10;
• Fig. 12 shows a spray gun similar to that of Fig. 1 but with an alternative form ofpaint reservoir;
• Fig. 13 shows the gun of Fig. 12 with a modified form of paint reservoir;
• Fig. 14 illustrates a modification to the reservoir of the gun of Fig. 13.
• Fig. 15 is a view, similar to Fig. 3, of an alternative form of paint reservoir,
• Figs. 16 and 17 show modified forms of a component of Fig. 15;
• Fig. 18 illustrates the use of a holder for the paint reservoir of Fig. 15;
• Fig. 19 is a perspective view of a liner/container in accordance with the invention;
• Fig. 20 is a similar view but showing the liner/container in the process of beingcollapsed for disposal;
• Fig. 21 (a) to (c) is a diagrammatic illustration of a method for producing a liner forthe paint reservoirs of Figs. 2 to 4, and 10;
• Fig. 22 illustrates a modification of the method of Fig. 21;
• Fig. 23 shows a paint-mixing pitcher; and
• Fig. 24 shows a liner in accordance with the invention, for use with the pitcher ofFig. 23.
• Fig. 1 of the drawings illustrates a typical prior artpaint spray gun 1 of the gravity-feedtype. Thegun 1 comprises abody 2, ahandle 3 which extends downwardsfrom the rear end of the body, and aspray nozzle 4 at the front end of the body.The gun is manually-operated by atrigger 5 which is pivotal-mounted on the sidesof the gun. The paint reservoir, or paint pot, 6 which contains paint (or similarmaterial) to be discharged by the gun, is located on the top of thebody 2 andcommunicates with an internal passageway (not visible) for compressed air, whichextends through the gun from a connector 7 at the lower end of thehandle 3 to thenozzle 4. In use, the connector 7 is connected to a source of compressed air (notshown) so that, when the user pulls on thetrigger 5, compressed air is deliveredthrough the gun to thenozzle 4 and entrains and atomizes paint which is beingdelivered under gravity from the pot 6. The paint is then discharged through thenozzle 4 with the compressed air, as a spray.
• The paint which is contained in the pot 6 is often mixed by hand (for which aseparate receptacle, for example a jug, is required), and poured into the pot. Toensure that there are no unwanted particles in the paint, which would spoil the finishof the painted surface, the paint is usually poured into the pot 6 through a filter.Fig. 1 shows thecap 8 of the pot 6 removed for this purpose, and a conical filter 9about to be positioned on the open end of the pot. The filter 9 is shown as being a known type of disposable conical filter, having solid sides and afilter mesh portion10 at the pointed end of the cone. When the pot 6 has been filled with paint, thefilter 9 is removed and discarded, and thecap 8 of the pot is replaced. If the filter 9is a reusable filter then, like the gun, it should be cleaned thoroughly before it isused with a different liquid (e.g. a paint of a different colour or a liquid having adifferent chemical composition).
• Fig. 2 illustrates the components of an alternative form ofpaint pot 11 which can beused on thegun 1 of Fig. 1 (or any similar gun) instead of the pot 6. The alternativeform ofpaint pot 11 is shown assembled in Fig. 3 and (in cross-section) in Fig. 4.
• Thepaint pot 11 comprises anopen container 12, comparable in size to aconventional paint pot of a hand-held spray gun, having anair hole 12A in its baseand provided with adisposable liner 13. Theliner 13 corresponds in shape to (andis a close fit in) the interior of thecontainer 12 and has anarrow rim 14 at the openend which sits on the top edge of the container. Thecontainer 12 also has adisposable lid 15 which is a push-fit in the open end of theliner 13. Thelid 15 has acentral aperture 16 (Fig. 4) from which extends aconnector tube 17 provided, at itsend, withoutward extensions 18 forming one part of a bayonet connection. Theaperture 16 is covered by afilter mesh 19 which may be a push fit into the apertureor may be an integral part of thelid 15. Thelid 15 is held firmly in place on thecontainer 12 by anannular collar 20 which screws onto the container, on top of thelid.
• Thepaint pot 11 is attached to thespray gun 1 through the use of anadapter 21shown, separated from the paint pot, in Fig. 3 and (in cross-section) in Fig. 4. Theadapter 21 is a tubular component which, at oneend 22, is formed internally withthe other part of the bayonet connection for attachment to theconnector tube 17 ofthepaint pot 11. At theother end 23, the adapter is shaped to match the standardattachment of the spray gun paint pot (typically a screw thread).
• Theliner 13 of thepaint pot 11, as already mentioned, corresponds in shape to theinterior of thecontainer 12 and has anarrow rim 14 at the open end which sits onthe top edge of the container. As described below, the liner is self-supporting but isalso collapsible and, preferably, has a comparativelyrigid base 13A andcomparativelythin side walls 13B so that, when it collapses, it is in the longitudinaldirection by virtue of the side walls collapsing rather than the base. In addition, theliner 13 has no pleats, corrugations, seams, joints or gussets, and also no groove atthe internal junction of theside walls 13B with thebase 13A. A liner of that typewill be described in greater detail later with reference to Figs. 19 and 20. Alsodescribed below is a thermo-forming process by which such a liner can beproduced.
• Thecontainer 12 of thepaint pot 11 is formed from a plastic material, for examplepolyethylene or polypropylene, and may be translucent (as shown in Fig. 2) oropaque, and of any suitable size. For use with a paint spray gun, containers havinga capacity of 250, 500 or 800 ml could typically be used, although other sizes couldbe used if required. Thelid 15 is also formed from a plastic material, for example,polyethylene or polypropylene, and may be formed by an injection mouldingprocess. The lid may be translucent or opaque and may be coloured. Thecollar 20may be a moulded plastic component, or it may be a machined metal (for example,aluminium) component. Theadapter 21 may be a machined metal component andmay, for example, be formed from aluminium and anodised.
• To use thepaint pot 11, theadapter 21 is attached (at the end 23) to the spray gunand is left in position. Then, with thepaint pot 11 disassembled as shown in Fig. 2,theliner 13 is pushed inside thecontainer 12. Paint is then put into the container,thelid 15 is pushed into place and thecollar 20 is screwed down tightly to hold thelid in position. The top portion of theliner 13 is then trapped between thelid 15and thecontainer 12, and theliner rim 14 is trapped between the top edge of thecontainer and thecollar 20, as shown in Fig. 4. Advantageously, thelid 15 isformed with barbs (not visible) on its surface to engage and hold the top of the liner. Thespray gun 1 is then inverted from its normal operating position so thatthe end of theconnector tube 17 can be attached to theadapter 21 as illustrated inFig. 5, after which the gun can be returned to its normal position (illustrated in Fig.6) and is ready for use in the usual way. As paint is removed from within theliner13, the sides of the liner collapse as a result of the decreased pressure within theliner. The base of the liner, being more rigid, retains its shape so that the liner tendsto collapse in the longitudinal rather than the transverse direction thereby reducingthe possibility of pockets of paint being trapped in the liner.
• The user can choose to evacuate the air from within theliner 13 before operatingthespray gun 1 although that is not essential. It does, however, increase the rangeof angles at which the gun will function satisfactorily since there is no risk of airentering the gun from thepaint pot 11. To evacuate the air from within theliner 13,thetrigger 5 of the gun should be actuated while the gun is still in the positionshown in Fig. 5.
• After use, when the gun is to be cleaned, the gun can be re-inverted and thetrigger5 can be actuated briefly to allow paint within the gun to drain back into the liner inthepot 11. Thepot 11 is then removed from the gun by detaching theconnectortube 17 from the adapter 21 (which remains on the gun). Thecollar 20 is removedfrom thecontainer 12, and thelid 15 is then pulled out, bringing with it thecollapsed liner 13, as shown in Fig. 7. The lid (including the filter 19) and liner arediscarded, leaving thecontainer 12 andcollar 20 clean and ready for re-use with afresh liner and lid. Only the gun itself needs to be cleaned, resulting in a substantialreduction in the amount of solvent used. The risk of unused paint spilling from thepot 11 is also substantially reduced because theliner 13 is removed and discardedwith thelid 15 in place. Moreover, because the liner is discarded in a collapsedcondition, the amount of space required for collection of used liners is minimized.
• Because theliner 13, as described above, is an accurate fit inside thecontainer 12and has a smooth internal surface, it is possible to mix paint in thecontainer 12 itself rather than in a separate receptacle. In that way, cleaning of a separate mixingreceptacle can be eliminated to achieve a further reduction in the amount of solventused. That possibility does not exist when using a gravity-feed gun with aconventional paint pot, as shown at 6 in Fig. 1, because the latter is open at bothends. The possibility of theliner 13 being punctured or damaged by the mixingimplement is minimised, first because the liner fits inside thecontainer 12 exactlyand, second, because the self-supporting nature of the liner (described below)means that it is less likely to be dragged around inside the container during themixing process. To facilitate the use of thecontainer 12 as a mixing receptacle, theside walls of the container may be provided with markings 25 (Figs. 2 and 3)enabling the volume of the contents of the container to be determined. The generalshape of thecontainer 12 and, in particular, the fact that it is flat-bottomed andstable when in the orientation shown in Fig. 2 makes it particularly suitable for useas a mixing receptacle, as does the fact that it is translucent as already described. If,however, thecontainer 12 is opaque, it could be formed with slots in the side walls,through which theliner 13 could be viewed to enable the user of the spray gun toassess the amount of paint in thepot 11 at any time.
• When paint is mixed in thecontainer 12, the inclusion of thefilter mesh 19 in thecontainer lid 15 prevents unwanted particles in the paint from entering the spraygun. Themesh 19 can be omitted, however, if the paint is textured, or if it is mixedin a separate receptacle and strained when it is transferred to the linedcontainer 12or if the presence of contaminants in the paint is unimportant.
• Although thecollar 20 of thepaint pot 11 is described above as being a separateitem, it could be combined with thelid 15, in which case it would also bedisposable. As a further alternative, the lid 15 (with theconnector tube 17 and themesh 19) could be formed as an integral part of theliner 13, to which it could beconnected by a hinge joint 26 as illustrated in Fig. 8. In that case, there is no needfor the lid to fit inside the mouth of the liner to ensure that the lid and liner will beremoved together from the container after use: however, that would still be necessary if the lid were required to remain in place in the liner after use. As yetanother alternative, thecollar 20 could be replaced by a band secured around thetop of thepot 11 to hold thelid 15 andliner 13 in place. The band could be securedto thepot 11 and could, for example, be formed from rubber or be part of a metalclip arrangement of the type used to secure the tops of jars and bottles.
• If a more positive engagement is required between thelid 15 of Figs. 2 to 4 and theliner 13, the lid could be a snap fit with the liner instead of a push-fit as showm. Theliner could, for example, be formed with an internal circumferential rib positioned toengage in a corresponding groove on the adjacent surface of the lid.
• As yet a further alternative, the push-inlid 15 could be replaced by alid 27 havingthe form shown in Fig. 9. Thelid 27 is also a push-fit inside the liner but is generallyconical in shape and at itsupper end 28, corresponds in shape to the end of theconnector tube 17 of Figs. 2 to 4 so that it will engage in thesame adapter 21. Thelid 27 has an outwardly-extendingrim 29 which will sit on top of theliner rim 14,and a shapedportion 29A which will engage the internal surface of the liner. Theform of the shapedportion 29A allows thelid 27 to be pushed into the mouth of theliner and also provides arecess 29B into which the edge of the liner can thecontract so that the lid is securely located. The form of the shaped portionillustrated in Fig. 9 is not essential, however, and alternatives could be usedincluding, for example, barbs as described above with reference to thelid 15 of Fig.4. Thelid 27 is held in place on the container by a screw-on collar, similar to thecollar 20, which will sit on top of therim 29 of the lid. Thelid 27 may incorporate afilter similar to thefilter 19 of Figs. 2 to 5. Alternatively, in each case, the filter maybe generally cylindrical in shape so that it can be inserted into the tubular part of thelid from the end adjacent the bayonet connection. In that case, the internal shapingof the tubular part of the lid should ensure that the filter remains in position whenthe spray gun is in use.
• The components of an alternative form ofpaint pot 30 are illustrated in Fig. 10.Thepot 30, like thepot 11 of Fig. 2, comprises acontainer 12 and aliner 13. Inthis case, however, thefilter 19 of thepot 11 is formed as aseparate item 31 havinga diameter corresponding to that of thecontainer 12 and including acircumferentialsealing gasket 32. In addition, thelid 15 andcollar 20 of the pot of Fig. 2 arereplaced by a generally-conical lid 33 which is a screw-fit onto the container andwhich, at its upper end has atubular extension 34 of similar shape to theconnectortube 17 of Fig. 3 so that it will engage in thesame adapter 21. Thepot 30 isassembled by pushing theliner 13 inside thecontainer 12 and then, after paint hasbeen put into the container, placing thefilter 31 on top of the container andsecuring it in position by screwing down thelid 33. Therim 14 of theliner 13 andthe sealinggasket 32 of thefilter 31 are then both trapped between thelid 33 andthecontainer 12, as illustrated in Fig. 11, thereby preventing the leakage of paintfrom thepot 30 at this location when the pot has been secured to a spray gun and isinverted for use.
• Theadapter 21 could be dispensed with by forming the ends of thetubular parts 17,34 of lids of thecontainers 11, 30 with screw threads so that they can engagedirectly in the standard paint pot attachment on thespray gun 1.
• Fig. 12 illustrates an alternative spray gun in which the standard paint pot 6 of thespray gun 1 (see Fig. 1) is retained and is provided with aliner 35 which fits insidethe pot and, preferably, extends into the connection with thebody 2 of the gun toform a liquid-tight seal with the latter, for example through the use of a flexible O-ring(not visible) between the gun and the liner. In this case, theliner 35 does notcollapse when paint is removed from within the pot and may be formed from a morerigid material to assist in positioning it within the pot 6. Once in position, theliner35 is held in place by thecap 8 which is screwed down onto an outwardly-extendingrim 36 at the open end of the liner. The pot 6 of Fig. 12 is additionally providedwith afilter 37 which is of generally conical shape and formed entirely of meshmaterial and which, in use, is positioned inside theliner 35. Thefilter 37, like theliner 35, has an outwardly-extendingrim 38 which lies on top of theliner rim 36 andis likewise held in place by thecap 8 of the pot 6.
• The pot 6 of Fig. 12, unlike thepot 11 of Fig. 3 is intended to be filled with paintwhile attached to thespray gun 1. Theliner 35 andfilter 37 are placed in position,paint is poured into the pot, and the cap is fitted. During this operation, there is norisk of the filter being dislodged and, because the filter is formed entirely of meshmaterial, the user is always able to see the paint level while the paint is being pouredinto the pot. Thegun 1 is then ready for use. All of the paint dispensed by the gunpasses through thefilter 37 and there is, accordingly, no need for the paint to befiltered when it is being poured into the pot 6. After use, thecap 8 unscrewed is toallow thefilter 37 andliner 35 to be removed. Theliner 35 is discarded and thefilter 37 is either also discarded or is cleaned, depending on whether or not it isdisposable. The use of theliner 35 again reduces the amount of solvent required toclean thegun 1, with a further reduction being possible through the use of adisposable filter 37.
• Thefilter 37 can have any suitable shape and may, for example, have fluted sides toincrease the effective surface area of the filter.
• In a modified arrangement, illustrated in Fig. 13, theliner 35 and thefilter 37 arecombined to form asingle unit 39. In this case, the filter is discarded with the liner.
• In each of the arrangements shown in Figs. 12 and 13, theliner 35 andfilter 37 canbe removed from the pot 6 with thelid 8. In that case, it is possible to replace theconventional lid 8 of the pot 6 by a disposable lid so that thelid 8,liner 35 andfilter37 can be discarded together.
• Thedisposable unit 39 of Fig. 13 could be modified so that it would replace thepaint pot 6 of thespray gun 1 instead of being fitted inside the paint pot. In thatcase, theunit 39 could be supplied as a sealedcartridge 50 already filled with paint as illustrated in Fig. 14. Externally, thecartridge 50 is similar to the paint pot 6 andcan be connected to thegun 1 in the same way. Because it is sealed, however, theoutlet end 51 of the cartridge must be pierced and an air vent provided, for exampleat theother end 52 of the cartridge, to allow paint to flow into the gun. Theoutletend 51 of thecartridge 50 could, for example, be pierced by the user before thecartridge (with the outlet end uppermost) is attached to the (inverted) gun.Alternatively, thegun 1 could be modified so that theoutlet end 51 is piercedautomatically when thecartridge 50 is attached to the gun. An air vent at theotherend 52 of thecartridge 50 could then be formed after the cartridge has beenattached to the gun by piercing that end of the cartridge either manually or, forexample, by attaching aseparate cap 53 which is designed to pierce the cartridgewhen it is placed in position. Alternatively, an air vent, which simply needs to beopened when the gun is ready for use, could be pre-formed in the cartridge.
• After use, thecartridge 50 is removed from the gun and discarded. Because thecartridge 50 contains a filter, there is no need for the supplier to filter the paintbefore it is loaded into the cartridge. If, however, the paint is pre-filtered, then thefilter in thecartridge 50 can be omitted.
• Fig. 15 illustrates an alternative form ofpaint pot 40 for aspray gun 1, which isentirely disposable. Thepaint pot 40 is generally similar to thepot 30 shown in Fig.10 except that thecontainer 12 is replaced by adisposable container 41, describedbelow, and theliner 13 is omitted.
• Thecontainer 41 of Fig. 15 can be any conventional disposable container suitablefor containing paint and for attachment to thepaint pot lid 42. Thecontainer 41may, for example, be formed from a thin plastic material, preferably translucent (asshown) so that the contents of the container are visible and preferably havingmarkings 43 on the side walls to enable the volume of the contents of the containerto be determined. Anair hole 44 is formed in the base of the container, togetherwith some means for closing the air hole when desired. That means may take the form of a strip of adhesive tape (not shown) which is peeled back to open thehole44 and can be re-adhered to close the hole when required. Alternatively, a flip-topclosure or some simple hand-operated valve mechanism may be provided. Thecontainer 41 has an external screw-thread at its open end, for attachment of thelid42 which is generally similar to thelid 33 of Fig. 10 and is likewise shaped, at itsupper end 42A, for attachment to a spray gun (if necessary by means of a suitableadapter). Thelid 42 may be formed from the same material as thecontainer 41 and,as shown, may also be translucent. Aflat filter mesh 45, which is also disposable,extends across the mouth of thecontainer 41. Themesh 45 may be a separate item,held at its periphery between thelid 42 and thecontainer 41, or it may be formedintegrally with the lid.
• To use thepot 40, thelid 42 andfilter mesh 45 are removed from thecontainer 41which is then filled with paint (care being taken that theair hole 44 in the base ofthe container is closed). It is unnecessary to strain the paint when it is put into thecontainer 41 and, as described above, it is possible to mix the paint in the containerthereby avoiding the need for a separate receptacle for that purpose. Thelid 42 andmesh 45 are then put back in position on thecontainer 41, thelid 42 is attached tothe (inverted)spray gun 1 which is then returned to its normal position, and theairhole 44 in the base of the container is opened. Thespray gun 1 can now be used inthe usual way. On completion of the spraying operation, theair hole 44 is closed-offagain, thepot 40 is detached from thegun 1 and may then be discarded leavingonly the gun to be cleaned. Before thepot 40 is detached, thespray gun 1 can bere-inverted and thetrigger 5 of the gun operated to allow excess paint remaining inthe gun to drain back into the pot. In either case, if sufficient paint remains in thepot 40, the pot could be re-sealed (instead of being discarded) and used again.
• Advantageously, thecontainer 41 of the pot is formed so that it can be collapsedafter use. In some cases, it may be possible for thelid 42 also to be collapsible.
• As an alternative, thelid 42 could be a reusable component and would be cleanedwith the gun. With an arrangement of that type, it is possible for thedisposablecontainer 41 to be supplied as a cartridge already filled with paint and sealed by acover which would simply be removed before the container is attached to thelid 42.Thefilter mesh 45 could be either a disposable or a reusable component. As afurther alternative, thecontainer 41 andlid 42 together could be supplied as acartridge sealed by a removable cover, at theupper end 42A of the lid, which wouldbe removed before the cartridge is attached to the gun. In that form, the cartridge issimilar to thecartridge 50 of Fig. 14.
• Through an appropriate selection of the dimensions of thelid 42 of thepaint pot 40,it is possible for the onelid 42 to be used withcontainers 41 of different sizes. Theuser would then select, in each case, thecontainer 41 that contains the most suitableamount of paint. It may also be desirable for a range offilters 45 having differentmesh sizes to be provided so that the user can select the mesh size that is best suitedto the type of paint that is being used. It is not essential for thefilter mesh 45 tohave the form and/or location shown in Fig. 15: it could, for example, have aconical form as shown in Fig. 16 and/or it could be located in the outlet of thelid42, as shown in Fig. 17. Alternatively, thefilter 45 can be omitted if the paint isfiltered before it is put into thecontainer 41, or if the presence of contaminants inthe paint is unimportant.
• Thelid 42 need not have the exact shape shown in Fig. 15 and could, for example,be replaced by a push-in lid in combination with a screw-on collar as shown in Fig.2.
• When the container 41 (with or without the lid 42) is supplied as a cartridgecontaining paint (or other coating material) it may be desirable in some cases for thepaint/coating material to be contained within a sealed collapsible liner within thecartridge. That may, for example, be desirable if it is necessary for the paint/coatingmaterial to be kept isolated, for example from the air or from light, until it has been sprayed onto the surface to be coated. Theair hole 44 in thecontainer 41 can thenremain open all the time, or may be omitted if thecontainer 41 itself is not airtight.
• Depending on the shape of thecontainer 41, it may be desirable to provide a holderin which the container can be located to ensure that it will not be knocked over.Onesuitable holder 50, shown in Fig. 18, comprisescontainer portion 51 which isof similar shape to, but slightly larger than, thecontainer 41 and is provided with anenlarged base 52. Thecontainer 41 is placed in thecontainer portion 51 to ensurethat it remains upright while it is being filled and/or attached to thespray gun 1.
• Although the above description refers to a paint spray gun, it should be understoodthat it applies also to other types of spray gun including. for example, guns of thetype which are attached to water hoses (rather than air supply lines) for sprayingsubstances such as garden chemicals. The description also applies to suction-feedguns, i.e. guns in which the liquid outlet from the reservoir is located at the top ofthe reservoir when the gun is in use and liquid is drawn from the reservoir through asupply tube by the action of the compressed air or other pressurized fluid flowingthrough the gun. In that case, when a liner is provided for the reservoir, theconstruction of the liner and/or the supply tube should be such that the liner cancollapse without blocking the supply tube. For example, a short supply tube can beused provided all air is exhausted from the liner before the gun is used.Alternatively, a flexible supply tube could be used, which will collapse with theliner. As a further alternative, a modified liner which does not have a rigid basecould be used, so that the liner collapses in a different manner from theliner 13 ofFig. 2. Since the reservoir of a suction-feed gun is not inverted during use, as in agravity-feed gun, it is possible to omit the air hole in the reservoir, provided theconnection between the reservoir and the gun permits air to enter the spacebetween the reservoir and the liner.
• Returning now to thepaint pot 11 of Fig. 2, theliner 13 will now be described ingreater detail, together with a method by which it can be produced. The liner, shown in isolation in Figs. 19 and 20, is preferably transparent and is thermoformedfrom a single piece of plastics material, preferably polyethylene orpolypropylene. The shape of the liner is dictated by the internal shape of thecontainer 12. The comparativelyrigid base 13A is circular and theliner 13, like theinside of thecontainer 12, is generally cylindrical but tapers inwards slightly fromthe mouth towards thebase 13A. Therim portion 14, like the base, is alsocomparatively rigid but theside walls 13B are flexible and, as already described, canbe made to collapse. Nevertheless, theliner 13 is capable of standing, unsupported,on thebase 13A with theside walls 13B extended and upright as shown in Fig. 19.When theliner 13 collapses, the comparativelyrigid base 13A retains its form butmoves towards therim portion 14 of the liner as a consequence of the collapse oftheside walls 13B, as illustrated in Fig. 20. Theside walls 13B collapse in a similarfashion to a plastic bag without being ruptured (e.g. by splitting, tearing orcracking).
• In one form, the liner has a height of about 110 mm, a diameter at itsbase 13A ofabout 78 mm and a diameter at its mouth (excluding the rim portion 14) of about 86mm. The base has a thickness of about 400 µm, therim portion 14 has a thicknessof about 900 µm, and theside walls 13B have a thickness of about 150 µm. Inanother form, the liner has the same height and the same diameters at its base andmouth but the base has a thickness of about 300 µm, the rim portion has a thicknessof about 200 µm, and theside walls 13B have a thickness in the range of from 50 to250 µm.
• A method of producing a liner as shown in Fig. 19 will now be described withreference to Fig. 21 (a)-(c).
• Asheet 60 of low density polyethylene (LDPE), approximately 250 x 225 mm and0.5 mm thick, was clamped at its periphery in themoulding frame 61 of a vacuum-formingmachine. The LDPE material is commercially available from, for example,Plastech Extrusions Ltd. ofWidnes, Cheshire, England and the vacuum-forming machine used was the model "FLB 725" from C.R.Clarke and Company Limited ofAmmanford, Carmarthenshire, Wales. It will be appreciated, however, that anysuitable plastics material could be used and that the method could be carried outusing any suitable thermo/vacuum-forming machine.
• After thesheet 60 had been placed in position, the bank ofheaters 62 of thevacuum-forming machine was moved into position above the sheet (as shown inFig. 21(a)), and the sheet was heated to a soft, pliable, state suitable for vacuum-forming.The fact that the sheet had reached the appropriate temperature could beseen by the change in its appearance from milky to transparent.
• The bank ofheaters 62 was then removed and themould platen 63 was movedupwards from below thesheet 60, bringing themould 64 into contact with the sheetto deform the latter in an upwards direction. At this time, the vacuum pump of themachine was switched on to remove air from beneath thesheet 60. The upwardmovement of themould platen 63 was continued until the platen reached the top ofits stroke, where it seals against theframe 61 holding the sheet 60 (Fig. 21(b)). Themould 64 had a shape corresponding to the internal shape of thecontainer 12 of thespraygun paint pot 11.
• Operation of the vacuum pump was continued with the mould platen sealed againsttheframe 61 and the pressure difference created between the upper and lower sidesof thesheet 60 caused the latter (which was already in contact with the top of themould 64) to move down into contact with the sides of the mould (Fig. 21(c)). Themould platen 63 was then moved away from the cooledsheet 60 leaving a mouldedportion 65 having the desired shape of theliner 13 and without any pleats,corrugations, seams, joints or gussets, or any groove at the internal junction of theside walls 13B with thebase 13A. Following removal from theframe 61, thesheet60 was trimmed around the mouth of the mouldedportion 65 to form therim 14 oftheliner 13. The width of therim 14 is determined by the location at which thesheet 60 is trimmed at this stage, and can be adjusted as required.
• The above-described process was found to yield a moulded portion 65 (and hence aliner 13) in which that part of theplastics sheet 60 that had been in contact with thesides of themould 64 during the forming process was substantially thinner than thepart that had been in contact with the top of the mould. The process differs from aconventional vacuum-forming process which would aim to eliminate, as far aspossible, any differences in thickness in the mouldedportion 65 and, to that end,would include the additional step of applying air pressure to the underneath of theheated sheet 60, after step (a) of Fig. 21, to cause the sheet to adopt a dome shapebefore themould platen 63 seals against the frame 61: the thickness of the sheetwould then be comparatively even when it moves into contact with themould 64 instep (c) of Fig. 21. Generally in the process illustrated in Fig. 21, for a given size ofsheet 60, the size of themould 64 has been found to affect the thickness of the sidesof the resultingliner 13 more than the base. In other words, if the size of themould64 is increased, the thickness of the base of the resultingliner 13 will be about thesame but the sides of the liner will be much thinner. On the other hand, if the sizeof the mould is decreased, it may be found that a point is reached at whichlongitudinal creases appear in the sides of theliner 13.
• If a further reduction is required in the thickness of thesheet 60 where it contactsthe sides of themould 64 in step (c) of Fig. 21, thesheet 60 can be located betweentwo thin metal plates 66 (Fig. 22) when it is clamped in theframe 61 of the formingmachine, eachmetal plate 66 having ahole 67 in the location of themould 64 andlarger in size than the largest cross-section of the mould. Theplates 66 are alsoclamped in theframe 61 and the process of Fig. 21 is then repeated. The effect oftheplates 66 is that only the central portion of thesheet 60 is exposed directly totheheaters 62 and is drawn over themould 64 when the latter has been movedupwards (in this case, through theholes 67 in the plates 66). In that way, less of thesheet 60 is used in the formation of the mouldedportion 65 and the resultingliner13 will have a slightlythinner base 13A and rim 14 and substantiallythinner side walls 13B. It is also possible to obtain a comparable result by using only theupperplate 66 shown in Fig. 22.
• As a modification of the process illustrated in Fig. 22, theplastics sheet 60 can be inthe form of a circular disc of material which is clamped at its periphery between thetwoplates 66. Depending on the size of the disc, the clamped periphery may thenform therim 14 of theliner 13 and there may be no excess material to be trimmedaway.
• It has been found that aliner 13 produced by a process as described with referenceto Figs. 21 and 22 will collapse as described with reference to Fig. 20 when used inthespray gun reservoir 11 of Fig. 2. Theliner 13 can also be collapsed by hand bypushing thebase 13A of the liner towards therim 14. It has been found that theliner is typically capable of standing unsupported on itsbase 13A and this feature,although not essential to the use of the liner in thespray gun reservoir 11, may be ofuse for storage purposes. The liner has no pleats, corrugations, seams, joints orgussets, and no groove at the internal junction of theside walls 13B with thebase13A: consequently, there are no internal locations in which material within the linercan become trapped. Thebase 13A of the liner will, of course, occupy some spaceat the base of thecontainer 12 of thespray gun reservoir 11 and the markings onthe wall of thecontainer 12 need to be positioned to take account of that fact.
• Although theliner 13 of Fig. 19 has been described for use specifically in thepaintpot 11 of Fig. 2, the same or a similar article can be used in other ways (subject, ifnecessary to appropriate dimensional changes). For example, an article of the typeillustrated in Fig. 19 can also be used as a liner in many forms of receptacle otherthan a spray gun reservoir. It is often desirable to provide a receptacle with adisposable liner, for example to keep the receptacle clean, to facilitate cleaning, orto protect the receptacle or its contents. A liner of the type illustrated in Fig. 19 canbe used for any of those purposes and is especially useful in receptacles in which substances are mixed together because there are no locations on the inside of theliner in which material can become trapped and remain unmixed.
• An article of the type illustrated in Fig. 19 can, for example, be used as a liner in areceptacle intended for paint mixing in a vehicle body shop, in which case it willprovide an attractive alternative to the disposable drinking cups which are oftenemployed for that purpose. Prior to painting the repaired portion of a vehicle in abody shop, the repairer must mix-up a batch of paint of the required colour,matching the colour of the surrounding portion of the vehicle. The variouscomponents for a batch of paint should be measured-accurately, either by volume orby weight, into a suitable receptacle in which they are mixed together thoroughlybefore being used. If the mixing is less than thorough, or if the receptacle is notabsolutely clean, the colour/quality of the batch of paint (and, consequently, thequality of the repair) may be affected.
• To enable paint mixing to be carried out conveniently, but effectively, a liner of thetype illustrated in Fig. 19 can be used with a measuringvessel 70 as shown in Fig.23. The measuringvessel 70 is in the form of a pitcher having aspout 71 in ashapedrim 72 and ahandle 73. The pitcher is provided withmarkings 74 on theside walls, enabling the volume of the contents of the pitcher to be determined.Using the method already described with reference to Fig. 21, liners of the typeshown in Fig. 19 can be produced to fit accurately inside thepitcher 70 and, byutilizing such a liner, the various components for a batch of paint can be assembledand mixed together in thepitcher 70 without actually coming into contact with thelatter.
• Aliner 75 suitable for use in thepitcher 70 is illustrated in Fig. 24. Theliner 75 hasa shape corresponding to the interior of thepitcher 70 and is generally similar to theliner 13 illustrated in Fig. 19 except that the thicker, outwardly-extending,rimportion 14 of the latter is omitted and theside walls 76 of theliner 75 include ashaped rim 77 corresponding to therim 72 and spout 71 of the pitcher. Because theliner 75 fits the inside of thepitcher 70 exactly, the possibility that it will bepunctured by the mixing implement when paint is being mixed in the pitcher isminimized. In addition, because there are no locations in the interior of the liner inwhich material can become trapped, there is no banier to the effective mixing of allthe material that is measured into the pitcher. When the paint has been mixed andtransferred from the pitcher 70 (for example, to the paint pot of a spray gun), theliner 75 is removed, preferably collapsed as shown in Fig. 20, and thrown away,leaving thepitcher 70 clean and ready for further use.
• Because thebase 78 of theliner 75 will occupy some space at the bottom of thepitcher 70, themarkings 74 on the side walls of the pitcher may need to bepositioned to take account of that fact. It may also be desirable, depending on theshape of thepitcher 70, to provide an extension at the top of theliner 75 which canbe folded back over therim 72 of the pitcher. Alternatively, or in addition, it may bedesirable to seal theliner 75 to thepitcher 70 during use, for example by providingsome form of shaping on the liner and the pitcher so that they can be snap-fittedtogether at therims 77, 72.
• Although it is desirable that theliner 75 of thepitcher 70 should be collapsible sothat it occupies less space after use, that is not absolutely essential. Moreover, sincethe shape of theliner 75 is determined by the shape of the interior of thereceptacle70 in which it is to be used, there may be cases in which the liner is not capable ofstanding, unsupported, outside the receptacle.
• As a further alternative, an article of the type shown in Fig. 19 can be used simplyas a container in which case it has the advantage that, although thewalls 13B arecomparable in flexibility to a plastic bag, the container will stand upright, withoutsupport, while it is being filled and also afterwards. The container can be of anyappropriate size and can be used to contain many different types of items, includingfor example powders and liquids, or simply as an alternative to the plastic/paperbags provided to customers by retailers. In each case, the container has the advantage that there are no internal locations in which material within the containercan become trapped. Depending on the contents of the container, it may bedesirable to be able to close the container mouth, in which case some appropriateform of closure can be provided. The closure may, for example take the form of aninternal rib on the inside of the container around one half of the mouth, and amating groove also on the inside of the container around the other half of the mouthinto which the rib can be pressed to close the container. The flexibility of thecontainer walls 13B additionally allows the walls to be pressed down around thecontents, thereby reducing the air space within the container if required.
• After use, when it is required to dispose of the container, theside walls 13B can becollapsed by hand by pushing therim 14 towards the base so that the container(now in the form illustrated in Fig. 20) requires less space for disposal. As alreadymentioned, theside walls 13B collapse in a similar fashion to a plastic bag withoutbeing ruptured (e.g. by splitting, tearing or cracking).
• It will be appreciated that there are many other possible uses for articles of the typeshown in Fig. 19. A liner of that type could, for example, be used simply as a linerfor a refuse bin where it would offer the advantage of being a better fit inside thebin than a conventional bag-shaped liner, and of being easier to handle whenremoved from the bin because it will stand upright on thebase 13A. Similar linerscould also be used in buckets or other containers for materials that hardencomparatively quickly (for example glue, wax or plaster): in some cases, materialsuch as plaster is actually sold together with a mixing bucket, in which case a supplyof liners could be included in the package. In some circumstances, it might beappropriate to have a plurality of liners, stacked one inside another, in positioninside a receptacle so that when one liner is removed the next is already in position.Moreover, since the receptacle is intended to contain a liner, it is not essential forthe walls of the receptacle to be solid: the receptacle could, for example, have theform of a framework for containing the liner.
• Generally, in an article of the type shown in Fig. 19, thebase 13A is typically atleast 25 µm thick, more typically at least 100 µm thick. Theside walls 13B are thinin comparison to thebase 13A, to the extent that they can be collapsed as describedto facilitate disposal of the liner/container: typically, the thickness of theside walls13B is less than half the thickness of thebase 13A and may be less than one fifth thethickness of the base. Depending on the materials used, and the intended use of theliner/container, theside walls 13A will usually be less than 250 µm thick.
• For certain uses of an article of the type shown in Fig. 19, therim portion 14 maynot be essential and can be omitted (as in the liner of Fig. 24). If norim 14 isrequired thesheet 60 of Fig. 21(c) would, of course, be trimmed immediatelyadjacent the mouth of the mouldedportion 65. It has been found that the self-supportingnature of the liner/container can be retained even if therim portion 14 isomitted.
• It should also be noted that thebase 13A of a container/liner of the type shown inFig. 19 need not be circular but could have another shape, for example rectangularor triangular. In the case of a liner for a receptacle, that shape may be dictated bythe shape of the receptacle particularly if the liner is required to fit the interior of thelatter. In some cases, the base need not be rigid.
• It will further be appreciated that the process illustrated in Figs. 21 and 22 is notrestricted to the production of liners for use in the paint pots of spray guns and canbe adapted to produce liners/containers for other purposes. It will be appreciatedthat the process requires themould 64 to have a slightly tapered shape with thelargest cross-section being at the lower end (as seen in Figs. 21 and 22) to allow thesheet 60 to be removed when the forming operation is complete. When the processis used to produce of a liner which is required to fit inside a container, that, in turn,requires that the container should be similarly tapered internally. Theliner/container may be formed from any suitable thermoplastic material capable offorming a thin film which is impervious to the materials it is intended to contain. In some cases, it may be desirable to use a material which is in the form of a laminate.For certain applications, such as food packaging, plastics with a low gas-permeabilitymay be preferred. For most applications, however, polyolefins such aspolyethylene or polypropylene are preferred since these a relatively cheap, arereadily thermo-formable, and are inert to most aqueous and organic fluids.

Claims (32)

1. Liquid spraying apparatus comprising a gravity feed spray gun anda reservoir (40), the reservoir (40) comprising a container (41) and aremovable lid (42), the lid (42) being arranged to close an opening in thecontainer (41) and provided with an outlet for transferring liquid from thereservoir (40) to an inlet of the spray gun.
2. Liquid spraying apparatus according to claim 1characterised in thatthe container (41) is made of a plastics material chosen so that contents ofthe container (41) are visible and has markings (43) to enable the volumeof the contents to be determined.
3. Liquid spraying apparatus according to claim 1 or claim 2characterised in that a base of the container (41) is provided with an airhole (44) that can be opened and closed.
4. Liquid spraying apparatus according to claim 3characterising inthat means is provided for opening/closing the air hole (44) comprising are-sealable strip of tape or a flip-top closure or a valve mechanism.
5. Liquid spraying apparatus according to any one of the precedingclaimscharacterised in that the reservoir (40) is provided with a filter(45) arranged to filter liquid withdrawn from the reservoir (40) throughthe outlet in the lid (42).
6. Liquid spraying apparatus according to claim 5characterised in thatthe filter (45) is located in the lid (42).
7. Liquid spraying apparatus according to claim 5 or claim 6characterised in that a range of filters (45) having different mesh sizes isprovided for selection of a suitable mesh size.
8. Liquid spraying apparatus according to any one of claims 5 to 7characterised in that the or each filter (45) is of flat, conical or cylindricalform.
9. Liquid spraying apparatus according to any one of the precedingclaimscharacterised in that the lid (42) is a screw fit on the container(41).
10. Liquid spraying apparatus according to any one of claims 1 to 8characterised in that the lid (42) is a push fit on the container (41).
11. Liquid spraying apparatus according to claim 10characterised inthat the lid (41) is secured by means of a screw-on collar.
12. Liquid spraying apparatus according to any one of the precedingclaimscharacterised in that the outlet is shaped for attachment to thespray gun.
13. Liquid spraying apparatus according to any one of claim 1 to 11characterised in that an adapter is provided for attaching the outlet to thespray gun.
14. Liquid spraying apparatus according to any one of the precedingclaimscharacterised in that means is provided for sealing the reservoir(40) when dis-connected from the spray gun.
15. Liquid spraying apparatus according to any one of the precedingclaimscharacterised in that the container (41) and/or lid (42) is disposableafter use.
16. Liquid spraying apparatus according to any one of the precedingclaimscharacterised in that a holder (50) is provided to receive thecontainer (41) in an upright condition for filling and/or attaching thereservoir (40) to the spray gun.
17. Liquid spraying apparatus according to claim 16characterised inthat the holder (50) comprises a container portion (51) which is of similarshape to but slightly larger than the container (41) and is provided with anenlarged base (52).
18. A gravity feed reservoir for a spray gun comprising a container(41) having a base and side walls extending from the base to an open endspaced from the base, and a removable lid (42) for securing to thecontainer (41) to close the open end and provided with an outlet fortransferring fluid from the reservoir (40) to a spray gun.
19. A gravity feed reservoir according to claim 18characterised inthat, in use, the reservoir (40) is inverted for transferring fluid to thespray gun and the base of the container (41) is provided with an air hole(44).
20. A gravity feed reservoir according to claim 19characterised in thatthe air hole (44) is adapted to be opened and closed as desired.
21. A gravity feed reservoir according to any one of claims 18 to 20characterised in that a filter (45) is provided for filtering fluid withdrawnfrom the reservoir (40) through the outlet.
22. A gravity feed reservoir according to claim 21characterised in thatthe filter (45) is located in the lid (41) and a range of filters havingdifferent mesh sizes is provided for selection of a suitable mesh size.
23. A gravity feed reservoir according to any one of claims 18 to 22characterised in that the container (41) is made of a plastics materialthrough which the contents of the reservoir (40) are visible and isprovided with markings on the sidewalls to indicate the volume of thecontents.
24. A gravity feed reservoir according to any one of claims 18 to 23characterised in that the reservoir (40) can be sealed when dis-connectedfrom the spray gun to store unused paint and re-connected when it isdesired to use the stored paint.
25. A gravity feed reservoir according to any one of claims 18 to 24characterised in that the container (41) can be stood upright on the basefor adding fluid with the lid (42) removed.
26. A method for use in gravity feed liquid spraying apparatus, themethod comprising the steps of:

    (a) providing a container (41) having a base and sidewalls leading fromthe base to the open end;

    (b) standing the container (41) in an upright condition on the base andadding liquid through the open end;

    (c) providing a lid (42) having an outlet and attaching the lid (42) tothe container (41) to close the open end;

    (d) connecting the outlet to a spray gun with the reservoir (40) invertedto position the base above the outlet and opening an air hole (44) in thebase; and

    (e) operating the spray gun to transfer liquid from the reservoir (40) tothe spray gun under gravity with the air hole (44) open.
27. A method according to claim 26 further comprising the step of:

    (f) closing the air hole (44) on completion of spraying, inverting thereservoir (40) to position the outlet above the base, and disconnecting theoutlet from the spray gun.
28. A method according to claim 27 further comprising the step of:

    (g) sealing the reservoir (40) to store unused liquid.
29. A method according to any one of claims 26 to 28 furthercomprising the step of:

    (h) mixing liquid added to the container (41) in step (b).
30. A method according to any one of claims 26 to 29 furthercomprising the step of:

    (i) providing a range of filters (45) of different mesh sizes, selecting afilter (45) having a suitable mesh size for liquid to be sprayed, andlocating the selected filter (45) in the lid to filter liquid withdrawn fromthe reservoir (40) in use.
31. A method according to any one of claims 26 to 30 furthercomprising the step of:

    (j) connecting the outlet in step (d) to an inlet on the spray gun toposition the reservoir (40) on top of the spray gun.
32. A method according to any one of claims 26 to 31 furthercomprising the step of:

    (k) providing a holder (50) to receive the container (41) in step (b) tolocate the container (41) in the upright condition.

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