GB2120956A - Process for decorative surface colouring and frosting - Google Patents

Abstract

A process for surface finishing of articles comprising the steps of applying a base coat of opaque enamel to desired parts of the article surface, applying one or more colour enamel finish coats, applying a layer of adhesive and coating with (translucent) particles to achieve a coloured optical surface coating effect.

Description

SPECIFICATION Process for decorative surface colouring and frosting This invention relates to a special process for colouring and frosting articles and is particularly concerned with the decoration and/or protective surface finishing of ornamental or jewellery articles moulded or electroformed from natural, formerly living, objects such as flowers, which may be those formed by the process taught in United Kingdom Patent No. 2031024. Such items are typically produced as souvenirs evocative of, say, a particular (often characteristic) natural or local flora or fauna, for example an orchid. The delicacy and fragility of living objects, such as flower petals, makes reproduction by conventional ornamental and/or jewellery fabrication techniques a laboriously skilled task of manual dexterity and/or complex apparatus.

According to one aspect of the invention, a process for surface finishing of articles comprises the steps of applying a base coat of opaque enamel to desired parts of the article surface, applying one or more colour enamel finish coats, applying a layer of adhesive and coating the adhesive with (decorative) particles to achieve a colour optical surface coating effect.

According to another aspect of the invention a process for producing coloured and frosted electroformed articles comprises the steps of electroforming an article by metallic electrodeposition upon an original object, cleaning the metal encapsulated object and removing, by chemical erosion, the original object material, to form an electrodeposited object mould, applying a metallic surface coating to the mould by electroplating, applying a base layer of opaque enamel incorporating a synthetic resin binder over desired areas of the electroplated, electroformed object mould or article, curing said enamel base layer, applying one or more coloured finish synthetic plastics enamel layers, curing said enamel finish layers, applying adhesive over desired surface areas and coating said adhesive with crystal particles to achieve an overall frosted coloured optical surface coating effect.

There now follows a description of a particular embodiment of the invention, by way of example only.

Ornamental articles of jewellery items are produced by electrodeposition of copper or other suitable base metals on formerly living objects or entities such as leaves, flowers, fruits, fishes, for example by the process taught in United Kingdom Patent No. 2031024. The metal encapsulated objects are treated, for example, by solvents and/or neutralisers, to rid them of any residual corrosive treatment process chemicals and original decaying organic matter.

Moulds of the natural formerly living objects can aso be made and replicas produced from these using appropriate materials of strength.

Alternatively, a master model of the ornament can be handcrafted out and reproductions made from it by moulding in metal or other materials.

Electroformed or cast objects are then given thin coatings of precious metals, such as gold, rhodium or other fairly inert metals, desirably after all surface irregularities or protrusions have been removed by, say, grinding and polishing. This coating is accomplished by a conventional electroplating process Proprietary plating baths for this purpose are available. Articles are finished to the specific recommendations for the particular baths used. All residual processing chemicals are removed from the plated objects by thorough water rinsing and subsequent drying.

A thin, even depth layer of white opaque enamel, suitably containing a synthetic resin binder, is applied over all or certain selected parts of the surface. In the latter case, the article can thereby be finished with some areas in its original plated substrate, for example gold, or other metallic colours and the rest of the surface coloured as will be described. The coated model is left to cure in a dust-free chamber according to conditions specified for the particular enamel use. This layer forms the undercoat for subsequently applied overlying coloured finish enamel(s) and must therefore have good adhesion both to the article and to the coloured finish enamel(s). Moreover, its opacity must ba very high.

Coloured enamel(s), suitably containing synthetic plastics binders, are then applied on the white enamel base. Application can be effected by spraying, dipping or hand painting with a fine brush, or a combination of such application techniques. An elaborate assortment of colours can be coated on the article by a combination of application techniques to simulate the natural colours of the corresponding living object. The article can also be given abstract design and colours. The coloured coats are cured in a dust-free cabinet under conditions specified for the organic coating system.

A control check for visual defects is carried out.

Defects include cracks in the enamel layer, poor adhesion and improperly coated surfaces. Visually defect-free enamel coloured objects are then frosted.

The frosting process involves the appliccation of an even depth, thin layer of adhesive over the surface to be frosted, including coloured enamel or uncoated plated or unplated metallic surface areas.

The adhesive must have good bond strength for bonding siliceous or synthetic plastics material to the surface. Additionally the adhesive should be clear, and not yellow or otherwise discolour with time, and retain consistent bond strength with aging.

After the adhesive has been applied, a compact, uniform depth layer of transparent colourless or coloured siliceous beads or grit particles is immediately coated upon the adhesive layer. Any excess beads are shaken or tapped off and the adhesive allowed to set, thus binding the beads firmly to the model. Some opaque beads can be included to give an attractive effect. The grit particles or beads must be of similar si7e to give maximum brilliance. Beads measuring 300 microns across are suitable for the purpose. The beads or grit particles can be of synthetic plastics, silicate or other crystal-like material that allows the underlying coloured enamels to be visible.

Claims (3)

1. A process for surface finishing of articles comprising the steps of applying a base coat of opaque enamel to desired parts of the article surface, applying one or more colour enamel finish coats, applying a layer of adhesive and coating with translucent particles to achieve a coloured optical surface coating effect.

2. A process for producing coloured and frosted electroformed articles, comprising the steps of electroforming an article by metallic electrodeposition upon an original object, cleaning the metal encapsulated object and removing, by chemical erosion, the original object material, to form an electrodeposited object mould, applying a metallic surface coating to the mould by electroplating, applying a base layer of opaque enamel incorporating a synthetic resin binder over desired areas of the electroplated, electroformed object mould or article, curing said enamel base layer, applying one or more coloured finish synthetic plastics enamel layers, curing said enamel finish layers, applying adhesive over desired surface areas and coating said adhesive with crystal particlesto achieve an overall frosted coloured optical surface coating effect.

3. A process for producing coloured and frosted surface finished electroformed articles are replicas of natural, formerly living entities, such as flowers, substantially as hereinbefore described.