EP1710214A1

EP1710214A1 - Applying colour to improvious surfaces

Info

Publication number: EP1710214A1
Application number: EP05251918A
Authority: EP
Inventors: Inks &Coatings Supplies Ltd. Tennants
Original assignee: TENNANTS INKS COATINGS SUPPLIE
Current assignee: TENNANTS INKS COATINGS SUPPLIE
Priority date: 2005-03-29
Filing date: 2005-03-29
Publication date: 2006-10-11

Abstract

Colour is applied to an impervious substrate by use of a spirit-based stain and optionally overcoated with a transparent lacquer.

Description

This invention is concerned with the application of colour to impervious surfaces and to the novel products and the variety of decorative finishes that can be achieved on an industrial scale as a consequence.
Paints and colourants for application to a substrate come in a wide variety of different formulations. In general the tint, pigment or colouring matter (the term "pigment" is used in a generic sense to include all such materials hereinafter) is dispersed or dissolved in a carrier or solvent. A paint or colouring composition may be made or mixed on the spot for a particular purpose but, more usually these days, is prepared in advance, most usually on an industrial scale.
The carrier or solvent employed will depend upon the use to which the paint or colouring composition is to be put. A wide variety of different carriers and solvents are known. Oil-based, water-based, spirit-based and resin or plastics-based paints are all known. Particular forms such as watercolours, oil paints, gouaches, acrylics and enamels are widely used for different purposes.
Traditionally, impervious materials such as glass and glass articles have either been coloured in the manufacturing process or by the use of enamels or of oil-based paints on the finished manufactured glass. These processes are relatively expensive and time-consuming and require a considerable degree of skill in order to obtain a pleasing effect. Other complex processes have also been proposed in the Patent literature.
Thus Parkinson, in GB 478301 , aims to achieve a "shot" appearance in glass by spraying what he refers to as "colours known as 'enamels' or 'stains' suspended in toluol, water or alcohol or mixtures of water and alcohol with or without the addition of small amounts of soluble adhesives". It is apparent in the context that what Parkinson is concerned with are really "enamels" in the true meaning of that term, as it is an essential step of Parkinson's process to fire the sprayed glass in order to render the colouring permanent.
EP 0083963 of United States Gypsum Company obtains a faux wood effect by impressing a metal surface with a wood-grain pattern, coating the pattern with an acrylic resin, and then applying a water-, alkyd- or oil-based stain to the acrylic surface, which is said to absorb the stain.
Tudor-Hart, in GB 2257929 , produces a distressed paint finish on a metal substrate by (a) applying to the metal substrate a powder spray coating of polyester or epoxy base coat, (b) firing the coated metal at 180-200°C to melt the coating and fuse it to the metal substrate, (c) applying a water- or alcohol- based stain, (d) applying a top coat of polyester or epoxy, and (e) baking at 180-200°C.
Cope, in US5334633 , obtains a wood-grain effect on a metal, plastic or wood substrate by first applying a uniformly coloured base coat containing pigments, resins and solvents, of which the primary solvent is xylene, although other volatile solvents such as alcohol may be present in minor proportions, then applying a wood grain pattern with ink, and finally applying a conventional wood stain coating, which may then be covered with varnish.
As will be explained in more detail hereinbelow, methods in accordance with the present invention enable impervious materials such as glass objects or decorative laminates such as melamine-formaldehyde laminates, to be coloured easily and quickly by unskilled personnel giving a wide range of aesthetically pleasing finishes that it would not have been previously possible to produce other than, possibly, on a craft basis. Methods in accordance with the present invention, as explained in more detail below, enable such finishes to be achieved on an industrial scale.
Although the techniques described in detail hereinbelow work particularly well when the substrate comprises a moulded glass object, particularly those made of heat resistant glass, in which the surface has been etched to produce an opaque translucent effect, the techniques can be applied, with minor variation only, to any suitable impervious material including, but not limited to, transparent glass, metal articles, stone, china, porcelain and decorative laminates.
In general, in its broadest aspect, the invention consists of use of a spirit-based stain to apply colour to an impervious substrate.
The invention also extends to an article formed of an impervious material that has been coloured by the application of a spirit-based stain to the impervious material.
The term "stain", as used herein refers to a composition including at least one pigment dispersed or dissolved in a spirit base. By "a spirit base" is meant a liquid dispersing medium or solvent primarily consisting of one or more alcohols.
Preferably, the invention is concerned with the application of two or more different colours by this technique to achieve a non-uniformly coloured effect.
As explained in more detail hereinbelow, colouring may be achieved by applying the stain by airbrushing, by brush or by dipping. A painting similar to that achievable on paper by the use of watercolours can be produced on an impervious substrate using methods in accordance with this invention. Textures such as stippling and grain effects are possible. The stain may be applied by pouring, by printing or by being imprinted once applied, by ragging and by stencils. A variety of faux effects are possible including faux Japanese lacquer, faux marble and stone, faux mosaic and faux stained glass. A variety of oxidation effects can be simulated on metalwork.
With impervious substrates and a spirit-based stain, it is believed that the colour is not absorbed by the material of the substrate; rather, it is believed that the colour simply dries on its surface as the spirit base evaporates. The colour appears to be permanent - unless the surface is exposed to further spirit-based stain or to the spirit base itself - but may be covered with a protective clear lacquer coat.
The invention is hereinafter more particularly described by way of example only with reference to the accompanying drawings, in which:-

Fig. 1 shows a typical pattern that may be produced by painting successive colours;
Fig. 2 illustrates a typical arrangement in which spots of different colours are applied at substantially the same time to a substrate and serve to repel each other; and
Fig. 3 shows a glass lampshade with a coloured pattern applied thereto by the use of a method in accordance with the present invention.

Commercially available spirit-based wood stains intended for colouring wood and wood substitutes (which are all pervious or water-absorbent materials to a greater or lesser degree) can be employed directly following the teachings of this invention, but I have found that useful primarily ethanol-based stains can readily be prepared as required by mixing an appropriate pigment with a solvent composition including ingredients within the preferred ranges set out in the table below. Table

Ingredient Concentration Range

Denatured Ethanol 39% to 49%

Propan-2-ol 22% to 42%

Butanone 4% to 9%

Butanol 2% to 4.5%
The quantity of pigment employed with the solvent composition will depend upon the depth and intensity of colour desired and the covering power of the pigment itself. For different desired effects, pigment may be present in the composition in as little as 1mg per litre or as much as 1kg per litre. There is no fixed range.
The resultant stain is a thin to viscous liquid, which, though partially miscible with water, is nevertheless generally applied without any added water in following the techniques described below. Because the composition produces a vapour that is heavier than air and is inflammable with a flashpoint generally between 0°C and 21°C, care must be taken to avoid naked flames and to provide adequate ventilation in application. Suitable protective clothing should also be worn.
The stain dries at normal room temperature in approximately 1 minute and in general, and especially where more than one colour is employed, no two pieces are exactly identical. The resultant finish is heat and weather resistant but further durability can be achieved by overcoating with a clear lacquer. Any errors or mistakes can be removed by application of the base solvent composition.
The invention is hereinafter more particularly described with reference to a number of specific examples: -

Example 1

A spirit-based stain is applied directly to a copper tile (or, in an alternative arrangement, to a decorative laminate, such as a melamine-formaldehyde laminate formed in conventional fashion but without the need for a specific patterned décor sheet, as the process described herein may provide the decorative effect, the end result being similar whichever such substrate is employed). In order to make the solvent composition less viscous and thus more easily applied by airbrushing, a solvent composition with a relatively higher ethanol concentration and a relatively lower concentration of the heavier ingredients is made up. The pigment is dispersed in the solvent composition and poured into the compression tank of an airbrush and diffused by means of its nozzle on to the surface of the metal tile. The stain can be sprayed evenly or at random intervals in order to achieve different effects. When applied evenly the solution creates a truly uniform, flat finish with a depth of colour. When the stain is allowed to partly dry or to dry completely and is then oversprayed, a different effect is achieved. The wet spray shifts the dry coat to create a watermarked effect. If a second, differently coloured stain is applied to an evenly coated semi-dry impervious surface, the first applied colour shifts from the point of application of the second colour leaving a pool of the second colour with a rim in which the two colours are blended. In order to achieve selected effects, the metal tile may be uniformly coated by airbrush with the first colour and then spots of a second colour may be applied in small regions by use of a spray bottle with selected different spray settings.
The arrangement shown in Fig. 1 shows the decorative finish that may be achieved with such an arrangement, a first colour 1 being uniformly applied by airbrush to the substrate 2 and additional colours 3, 4... being applied subsequently by spray bottle. The first colour 1 is shifted to provide regions of subsequently applied colour, and rims of mixed colour such as those at 5 and 6 are achieved where the colours meet and mix to some extent.

Example 2

Differently coloured stains pulled across a surface by means of a brush achieve a variety of different decorative effects. Different widths of brush can be used to create diverse brushwork and interesting effects. By loading the brush with more or less stain a different degree of bleeding or spread of one stain relative to another can be achieved across the substrate, as illustrated in Fig. 2 in which different colours 6, 7, 8 are applied to the substrate, preferably etched glass, to form regions 9 of mixed colour between the differently coloured stains.

Example 3

A faux textured effect can be achieved by using a hard brush with relatively few bristles and drawing the brush across the surface before the stain has dried to create a cross hatched effect not dissimilar to that of an open weave material.

Example 4

Differently coloured stains can be brushed together and blended in one stroke on a substrate. As a result a broad range of "painting" effects can be readily achieved. Landscapes or other pictures, such as flowers or other still life compositions can be created depending upon the artistic skill of the person applying the stain. Parallel lines of colour may be applied to the impervious glass surface and left to blend. Detail can be achieved by using a smaller brush dipped into the stain and then applied to the dried surface. Colours tend to blend and diffuse to assume the look of conventional watercolour work, but - unlike watercolours - here upon an impervious substrate.

Example 5

A variety of textured effects may be achieved. In particular, the stain may be stippled onto a surface by using a brush. The brush is dipped in the stain and then held at right angles to the impervious surface. The brush is raised and lowered onto the surface leaving a residue of stain and a grainy effect. Use of a hard brush causes the pattern to be more precise, while a soft brush produces a softer and a more blurred effect. This decorative effect is particularly useful when applied to moulded glass shades for lamps, the glass having first been provided with a finely etched surface providing an additional key for the stain.

Example 6

Using a brush to feather a semi-wet watermarked finish, produced as described above in Example 1, can modify the finish to simulate marble, alabaster or stonework, particularly if this is carried out on an etched translucent glass surface or on a decorative laminate surface. Appropriate pigments can represent different strata giving an effect of depth. Thus, after the flat plane of the marble, alabaster or stonework is simulated by the application of appropriate pigments to the surface using differently coloured stains, the work is allowed to dry. It is then oversprayed with a clear lacquer. This in turn is permitted to dry and is overworked with a small brush loaded with higher concentrations of pigment in the solvent spirit base in order to create a simulation of the cracks and imperfections noted in marble, alabaster, etc. A stained or gloss clear lacquer is sprayed on to the surface and whilst the lacquer is still wet the veining is brushed out in the direction of the graining, for optimum effect. While each piece will look different, the technique is straightforward and easy to learn, so that faux marble, alabaster and other stonework articles can readily be produced on an industrial scale.

Example 7

A grid of squares is marked out on to an impervious translucent etched glass substrate using latex masking fluid squeezed through a small nozzle and allowed to dry. Differently coloured spirit-based stains with relatively high pigment content are applied sparingly to individual cells of the resultant grid by brush and are allowed to dry. If the width of the latex line is chosen to be representative of the width of grouting between small pieces of tile, the resultant effect, when the masking is removed, is of a simulated mosaic.

Example 8

The process of the present invention can be used to manufacture faux stained glass. In this case the substrate is suitably clear glass rather than etched translucent glass. The stain is applied in a uniform coating, suitably by airbrushing to one surface of a panel of glass and is allowed to dry. This is repeated on the reverse side of the panel or sheet of glass using the same stain. For durability a clear varnish is applied to both sides of the glass panel or sheet. The glass is then cut into desired shapes and the individually cut shapes are then used as for conventional stained glass. Because the pigment is applied only to the surface of the glass on both sides and in a relatively simple and quick process, the resultant faux stained glass is considerably less expensive than conventional stained glass.

Example 9

Various stages of oxidation can be simulated on metal surfaces. To achieve such oxidation effects, a stain with a relatively lower pigment concentration is employed so that the metal can be seen through the applied stain and through different layers of applied stain. Thus, for a verdigris finish, three layers are suitably applied. The first layer is a brown-green stain applied with a brush. The second layer is a blue-green stippling effect produced with a brush. A final layer is a yellow-green sprayed lightly on to the surface and then blended slightly into the previous layers when the stain is semi-dry.

Example 10

The base spirit can be used to shift the finish so that a pigment applied uniformly to the substrate, suitably etched glass, is shifted by the application of base spirit without pigment causing gradations in the depth of pigment across the work.

Example 11

An article made of translucent etched glass, for example a glass shade for a lamp, may be dipped into spirit-based stain and then raised out of the stain to dry in air. Such a shade will have a circular opening at its centre for the light fitting and a rim at its edge. As the stain flows over the surface of the shade as it dries, the resultant effect gives an increasing depth of colour from the centre of the shade, where the lamp fitting opening is located, to the edge.

Example 12

An impervious surface, for example etched translucent glass, is provided with a base coating which may comprise the spirit base without pigment or a spirit-based stain with a relatively neutral pigment. By dropping stains with different colours, suitably chosen from relatively strong pigments in relatively high concentrations in the spirit base on to the host surface, the colours will tend to repel one another where they meet producing a decorative finish not unlike the appearance of oil on water.

Example 13

Spirit-based stains may be printed on to an impervious substrate; but a particularly interesting pattern can be achieved by first evenly coating the substrate with a particular stain, waiting 30 seconds and then applying pressure to the surface with a textured material such as calico or lace and then stripping the calico or lace from the surface after a further 10 seconds carrying with it some of the semi-dried stain revealing a fabric-like finish on the substrate. Fig. 3 shows the pattern that results if a sheet of bubble-wrap is pressed against the surface 10 of a glass lampshade evenly coated with a spirit-based stain, and stripped away after about 10 seconds.

Example 13

A piece of cloth is dipped into spirit-based stain and applied to an impervious substrate, suitably etched translucent glass, to which has been applied either base spirit or a uniform coating of a differently coloured stain, the surface having been allowed to become semi-dry. By raising and lowering the cloth on to the surface a ragging effect is achieved.

Example 14

A stencil is applied to an impervious surface such as that of etched translucent glass and a spirit-based stain is applied over the stencil by spraying, sponging, ragging or brushing over the cut-outs in the stencil to leave a precise design on the impervious surface. The hard edge of this design may be softened by using a soft brush before the stain has completely dried, thereby producing a blurred finish.

Example 15

A layered structure simulating Japanese lacquer may be produced as follows: Applying layers of stain to a substrate and applying a combination of matt and gloss lacquer between layers of the dried stain, results in a surface with an appearance of depth simulating Japanese lacquer.
Thus, it will be seen from the above Examples, that a very wide range of different effects can be achieved using the teachings of the present invention. The use of the techniques described hereinabove to produce a faux marble effect for a decorative laminate, which can be made durable by over-coating with a transparent, preferably clear, lacquer, is of particular value, since faux marble in which no two pieces will be identical can readily be produced by this means inexpensively on an industrial scale.
No doubt persons skilled in this field will be able to produce other effects using techniques utilising the teaching of this invention.
In all cases, the use of spirit-based stains on impervious substrates results in an article with a coloured finish that is durable under most conditions. However, if the finish were to be exposed to the base spirit or a spirit-based stain, this would affect the otherwise durable finish, as explained above and as exploited in certain Examples, but this is readily avoided by applying a coating of lacquer to seal the finish, again as explained above.

Claims

Use of one or more spirit-based stains to apply colour(s) to an impervious substrate.
A process according to Claim 1, wherein the substrate comprises glass, preferably transparent or translucent glass, a metal article, stone, decorative laminate, china or porcelain, and colour(s) is (are) applied to one or both sides of the substrate.
A process according to Claim 2, wherein the substrate comprises a moulded glass object, preferably a glass lampshade.
A process according to Claim 2, wherein the substrate comprises glass, a metal article, stone, china or porcelain, and, prior to the said application of colour(s), the surface of the substrate is etched to give a translucent effect.
A process according to any preceding Claim, wherein the stain(s) is (are) applied by (one or more of) airbrushing, brush, dipping, stippling, pouring, printing, imprinting once applied, ragging, sponging or by stencil.
A process according to any preceding Claim, wherein each of the said one or more stains comprises pigment mixed with a solvent composition individually within the ranges set out below: Ingredient Concentration Range Denatured Ethanol 39% to 49% Propan-2-ol 22% to 42% Butanone 4% to 9% Butanol 2% to 4.5%
A process according to any preceding Claim, wherein the substrate with applied colour(s) is overcoated with clear lacquer.
A process according to any preceding Claim, wherein, following application of a first colour, a second different colour is applied over at least a part of the first colour after the first colour has been allowed to dry or partially dry, causing colour in the dry or partially dry coat to shift, creating a watermarked effect.
A process according to Claim 8, including the further step of feathering the semi-wet watermarked surface with a brush to create a finish simulating marble, alabaster or stonework.
A process according to any of Claims 1 to 4, wherein an impervious substrate is dipped into a spirit based stain and raised from the stain sufficiently slowly for stain to flow over the substrate as it dries, imparting a graduated colour effect.
Use of a process according to Claim 1 to produce faux Japanese lacquer by applying successive layers of a spirit-based stain to an impervious substrate, the said successive layers being separated by layers of a combination of matt and gloss lacquer.
An article formed of an impervious material that has been coloured by the application of a spirit-based stain to the impervious material.
An article according to Claim 12 in the form of a faux watercolour picture produced on an impervious substrate; a segment of faux stained glass or of a stained glass window containing such segments; a metal article with a simulated oxidation effect thereon; an impervious material with a graduated colour effect thereon; faux Japanese lacquer on an impervious substrate; or faux marble on an impervious substrate, preferably a decorative laminate.