GB2250954A

GB2250954A - Improvements in or relating to decoration of ceramic ware

Info

Publication number: GB2250954A
Application number: GB9027654A
Authority: GB
Inventors: Robin Graham Pavitt
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-12-20
Filing date: 1990-12-20
Publication date: 1992-06-24
Anticipated expiration: 2010-12-20
Also published as: GB2250954B; GB9027654D0

Abstract

A ceramic transfer 10 and a method of applying surface formations to ceramic ware using the transfer 10. The transfer 10 comprises a backing sheet 12 to which is removably attached a decorative ceramic transfer body 14. The transfer body 14 comprises the same ceramic material (either raw or prefired and ground) as the item of ware to which the transfer body 14, is to be attached. The transfer body 14 further comprises other ingredients including glaze. The transfer body 14 is formed on the backing sheet 12, preferably from a plurality of sequentially applied layers 16. The method of application of the transfer body 14 to ware comprises releasing the transfer body 14 from the backing sheet 12 and attaching the transfer body 14 to an item of raw or preferred ware using an adhesive comprising flux. The ware and the ceramic transfer body 14 are then fired. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO DECORATION OF CERAMIC WARE The present invention concerns improvements in or relating to decoration of ceramic ware and particularly but not exclusively to means for and a method of providing decorative surface formations on ceramic ware.

Conventionally surface formations and raised decorations are provided on ceramic ware during the forming of the ware, for example in a mould having a relief formation engraved therein. The preparation and tooling required makes such moulds expensive, and often the moulds are only used for limited periods before the designs therein become worn and also dated. Further, a substantial percentage of such decorated ware is 'lost' during firing.

Raised decorations have been provided on ware by applying pre-moulded decorations to the ware. Such decorations have been moulded from a mould produced in a successive and complex procedure comprising making an initial, relatively large model of the decoration and from this model forming a plaster of paris, rubber or resin mould. A copy decoration is then formed in this mould. A further similar mould is made from this latest decoration and the process is repeated to create working moulds for production. During each repetition natural shrinkage or enlargement of the materials produces a relatively smaller or larger decoration. This procedure is very time consuming and expensive and is usually reserved for decorating commercially expensive items of ware.

It is an object of the present invention to obviate or mitigate these disadvantages.

The term "ceramic" as used in the following specification relates to fired and/or unfired material and the term "surface formation" is to mean formations and decorations that are substantially raised from a surface of the ware when applied thereto.

According to the present invention there is provided a ceramic transfer comprising a backing member and a decorative formation removably mounted on said backing member and including a ceramic material, the decorative formation being transferable from the backing member to an item to be decorated.

Preferably the ceramic material of decorative formation is the same material as the ceramic material of the item to which it is to be applied. The ceramic material may be in the raw unfired state or in a ground prefired state. The formation preferably includes also glaze and, optionally, pigment.

The formation preferably comprises a number of superimposed layers. The layers may have differing outlines such that the formation made up of a plurality of superimposed layers is profiled in its cross-sections perpendicular to the plane of the layer.

Preferably each layer is applied to the backing member or a preceding layer by a screen printing technique.

Preferably a covercoat is applied over the formation and the face of the backing sheet carrying the formation.

Preferably the covercoat is of a flexible plastics material.

The backing member may be paper impregnated or coated with adhesive which is capable of releasably holding the formation thereto. Preferably the adhesive is a soluble adhesive such that the formation can be released from the backing member on immersing the transfer in an aqueous solution.

Further according to the present invention there is provided a method of applying surface formations to ceramic ware comprising releasing a formation from a transfer of the type described in any one of the preceding six paragraphs, applying the formation to the ware and firing the ware and formation.

Preferably the ware is initially fired prior to the application of the formation.

Preferably the formation is applied to the ware by means of an adhesive substance including flux. The ware and formation attached thereto are preferably fired at a temperature substantially equal to or less than the initial firing temperature.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which; Fig. 1 is a perspective view of a ceramic transfer; and Fig. 2 is a section through II-II of the ceramic transfer of Fig. 1 on an enlarged scale.

Referring to the drawings, a ceramic transfer 10 comprises a backing sheet 12 and a ceramic transfer body 14. The sheet 12 is of a conventional transfer backing material as used for conventional transfers in the pottery and ceramics industry, such as thermoflat paper.

The sheet 12 has a gum or adhesive substance either incorporated therein or coated thereon. This gum or adhesive helps the ceramic transfer body 14 to releasably adhere to the sheet 12.

The ceramic transfer body 14 comprises substantially the same material as the body of the ware to which it is to be applied in an unfired state or a ground prefired state, and a proportion of glaze. The proportions of material to glaze and the type used is dependent upon the type of ceramic ware to which the transfer body 14 is to be applied, for example, a suitable proportion of material (substantially clay) to glaze for transfer bodies for use on china ware, is found to be approximately 90-92 ware body material to 10-8 of glaze weight for weight.

Colours such as body stains and underglaze colours may be included in the ceramic transfer body 14.

The transfer body 14 may be formed by screen printing as described below. The transfer body 14 may be built up of a plurality of layers 16. A cover coat 18 is applied on the transfer to enclose a ceramic body 14 between the sheet 12 and the cover coat 18. The cover coat is of a flexible, plastics material conventionally used in lithographic techniques for on-glaze or under-glaze decoration.

A method of producing the ceramic transfer 10 will now be described by way of example only.

The ceramic transfer body 14 comprises, as described before, ware body material and glaze. The constituents are initially in a substantially dry powder form and are mixed together with the addition of water to provide a substantially homogeneous mix. The mix may be passed through a filter to remove any large lumps and is then dried to powder form. The powder mix may at this stage (or at the earlier stage when mixed with water) have colourant added, for example, body stain or underglaze colourant.

The powder mix is then added to a suitable ceramic screen printing medium. The printing screens are formed in the conventional way and the mix is screen printed on to a sheet of thermoflat paper 12. The design printed on the sheet 12 by a single printing procedure is of only relatively small raised height (from the sheet 12) and formations of larger raised height may be formed by sequentially forming layers, one on top of the other, by repeated screen printing procedures. The design printed in various layers 16 may differ such that the vertical cross-section of the transfer body 14 is non-uniform, if desired. For example, referring to Fig. 2 each subsequent layer 16 is of smaller width (from left to right of the drawing) thereby forming a ceramic transfer body 14 with curved edges.

It is to be appreciated that the design of each layer 16 will be varied according to the contours of the body desired.

Between the successive layers 16 being applied during formation of the transfer body 14 each layer 16 is allowed to substantially dry.

When the ceramic transfer body 14 has been formed to the desired contours, a plastics material covercoat layer is applied. Two or more such covercoat layers may be applied if desired.

The ceramic transfer 10 may now be stored easily and conveniently until required.

It is to be appreciated that a plurality of transfer bodies 14 may be formed on a single sheet 12 so as, for example, to provide a repetitive pattern of contoured formations to be applied to the layer, or to build up a pictorial device or the like.

Application of the ceramic transfer body 14 to an item of ceramic ware involves initially the removal of the ceramic transfer body 14 and the covercoat layer(s) 18 from the thermoflat sheet 12. The adhesive used may be water soluble, such that upon submersion of the transfer 10 into an aqueous medium, the transfer body 14 and covercoat 18 are released from the sheet 12.

The ware to which the transfer body 14 is to be applied is preferably in bisque (biscuit) form (has been initially fired). It is to be appreciated that the transfer body 14 may be applied to ware in other fired or unfired states, for example the ware may be in the unfired, dry clay state.

Before the transfer body 14 is applied to the ware a substance commonly termed "slosh" is applied to the proposed area(s) of contact between the ware and the body 14. The "slosh" commonly comprises a flux in a synthetic or organic medium. This slosh fills any minute cavity in the surface of the ware and helps prevent air entrappment.

The transfer body 14 and the covercoat 18 are dipped into the slosh and applied to the ware in the desired position. The transfer is then lightly pressed onto the ware, perhaps with a sponge or squeege, to remove any air bubbles and excessive slosh which may be trapped between the body 14 the covercoat 18 and the ware.

Further transfers 10 may be applied to decorate the same item of ware as described above.

When all the desired transfer bodies 14 have been applied to the ware the ware is allowed to dry to substantially remove the synthetic or organic medium.

Drying may be accelerated using conventional techniques.

When the medium has been removed, the decorated ware is fired. The firing temperature required is found to be at or below the temperature required to produce the biscuit state of the ware. During firing the flux from the slosh between a ceramic body 14 and the ware and the flux in the ceramic transfer body, melt and upon re-solidification produce a secure attachment between the body 14 and the ware.

The ware may then be glazed and further decorated as required in any conventional manner.

The above described transfer 10 and means of applying contoured surface formations or raised decorations to ceramic ware provides a relatively easy, convenient and efficient tecnique. Such a technique does not require extensive tooling or patterned and relief moulds, since the decoration and formation are applicable to basic items of ware with no existing surface formations. Further, the technique can be used on biscuit ware and therefore the relatively large percentage of ware "lost" during the initial filing of the ware is in the basic and relatively cheap-to-produce form and only ware that has survived the initial firing is decorated etc. with the contoured transfer. There is no apparent shinkage of ceramic transfer upon firing, the decoration remains the same size as drawn.

Various modifications may be made without departing from the spirit and scope of the present invention. For example, any suitable backing member material may be used.

The proportions of material and the transfer body mix may be varied according to the application. Further additional materials may be added to the transfer body mix according to requirements. The cover member may be of any suitable material. The securing substance may be of any suitable material.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. A ceramic transfer comprising a backing member and d decorative formation removably mounted on said backing member and including a ceramic material, the decorative formation being transferable from the backing member to an item to be decorated.

2. A ceramic transfer according to claim 1, in which the ceramic material of the decorative formation is the same material as the ceramic material of the item to which it is to be applied.

3. A ceramic transfer according to claim 1 or 2, in which the ceramic material is in the raw unfired state.

4. A ceramic transfer according to claim 1 or 2, in which the ceramic material is in a ground prefired state.

5. A ceramic transfer according to any preceding claim, in which the formation includes glaze.

6. A ceramic transfer according to any preceding claim, in which the formation includes pigment.

7. A ceramic transfer according to any preceding claim, in which the formation comprises a number of superimposed layers.

8. A ceramic transfer according to claim 7, in which the layers have differing outlines such that the formation made up of a plurality of superimposed layers is profiled in its cross-sections perpendicular to the plane of the layer.

9. A ceramic transfer according to claim 7 or claim 8, in which each layer is applied to the backing member or a preceding layer by a screen printing technique.

10. A ceramic transfer according to any preceding claim, in which a covercoat is applied over the formation and the face of the backing sheet carrying the formation.

11. A ceramic transfer according to claim 10, in which the covercoat is of a flexible plastics material.

12. A ceramic transfer according to any preceding claim, in which the backing member is paper impregnated or coated with adhesive which is capable of releasably holding the formation thereto.

13. A ceramic transfer according to claim 12, in which the adhesive is a soluble adhesive such that the formation can be released from the backing member on immersing the transfer in an aqueous solution.

14. A method of applying surface formations to ceramic ware comprising releasing a formation from a transfer of the type described in any of claims 1 to 13, applying the formation to the ware and firing the ware and formation.

15. A method according to claim 14, in which the ware is initially fired prior to the application of the formation.

16. A method according to claim 14 or 15, in which the formation is applied to the ware by means of an adhesive substance including flux.

17. A method according to any of claims 14, 15 or 16, in which the ware and formation attached thereto are fired at a temperature substantially equal to or less than the initial firing temperature.

18. A ceramic transfer substantially as hereinbefore described with reference to the accompanying drawings.

19. A method of applying surface formation to ceramic ware substantially as hereinbefore described with reference to the accompanying drawings.

20. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.