This invention relates to decorative glass and to method and means for decorating glass, particularly sheet glass for windows.

So-called leaded glass is well known, including for windows and doors of buildings, glazing of cupboards such as display cabinets or bookcases etc., screens, even mirrors. Traditionally considered best are structures made up of individual panes of glass retained within lead framing extending between individual panes and about outer edges of the whole, whether all of plain clear glass or some or all patterned or textured, or some or most of coloured glass, often of different patterns or textures as for stained glass windows. Such traditional leaded glazing requires high skills and is time-consuming and expensive to make.

One alternative is for glass sheets, usually but not necessarily clear, to have patterns of lead strips stuck on them, whether just to one side or duplicated in registration on both sides for best effect. These are, of course, much cheaper than traditional leaded glazing, but are usually much less interesting, being devoid of variations of texture and/or colouration. More recently, self-adhesive plastic films have become

available, in various tints and colours, to go on areas bounded by stuck-on lead striping. Some such films are printed with multi-coloured designs of which different coloured parts can subsequently be outlined with dividing lead striping adhered thereto.

These alternatives to traditional leaded glazing are cheaper but generally fail to give a feel of being anything more than poor imitations of better things.

It is an object of this invention to provide a more satisfying result but without substantial increase of costs.

Achievement of that object is based first upon appreciating that a major failing of the above alternatives is absence of variation of texture or pattern between adjacent sub-areas of glass divided by adhered lead strips.

Being interested generally in decorative glass, the inventor hereof is familiar with inducing selective opacity of glass by particle erosion as widely used for applying lettering, decorative designs, symbols, even pictorial and other artistic work to glass, and generally employing resists from which the desired

lettering, design, etc. is absent. Modern resists include self-adhesive plastics sheet from which cut¬ outs are made corresponding to the desired effect, and selectively deposited resists often onto sheet that is itself non-resistant to particle-erosion. However, such methods are also time-consuming where cutting-out is required and/or where adhering selectively relieved pictorial items requires them to be carefully positioned. Also, these methods are generally of a one- operation type, i.e. require setting up anew, including any necessary cutting out, for each use or, at best, after only a very small number of repeated uses.

Particle erosion, typically by sand-blasting, thus appeared unpromising for successful development of a practical system of achieving a patterned or textured effect in an economic manner suitable for commercial exploitation on a reasonable scale. Nevertheless, experiments were conducted using sand-blasting, particularly for areas between or to be between lead striping, including sub-areas defined temporarily by masking tape for later division by lead striping. However, results were unsatisfactory in leading to areas and sub-areas unrelieved in imposed opacity or with displeasing patchiness.

Later, however, this invention did arise from contemplation of those unsatisfactory results and has led to glass decorated for a patterned or shaded effect by imposition at and for one or more selected areas thereof of plural further effective division into well defined differentially opaque formations, usually selectedly opaque and clear.

According to one aspect of this nvention there is provided a decorated glass sheet comprising ornamental strip applied about plural areas thereof and between each of any subareas of a said area or areas desired to be differently ornamented, which areas and any subareas thereof exhibit within themselves predetermined localised variations of ornamental surface erosion achievable by selective particle erosion, even on the uneven surface of a sheet of patterned glass. Coloured flat film may be adhered to flat glass surface within a said area or sub-area, or such area or sub-area may be painted.

Ordered definition of differential opacity in an array, particularly with a repeating pattern, is reliably achieved using one or more portions of expanded metal, for example steel or aluminium mesh, over the or each said area or sub-areas thereof, and directing glass

eroding particles therethrough. The expanded metal shields only clear definitions between formations that become opaque. Very satisfying results are achieved, especially from using different sizes and/or patterns of aperturing of expanded metal for different ones of plural said areas, or sub-areas thereof, preferably if not necessarily within an overall sheet having a predominance of uneroded surface, and with all said areas and subareas being between ornamental strip, say self-adhesive lead striping. Aperturing of expanded metal in a repeating pattern, often all apertures the same, results in effects that are particularly pleasing, hence considered advantageous but not necessarily limiting of invention.

Another way of defining differential opacity, particularly within areas of an overall design which areas are to be defined or divided from other areas by ornamental strip, is for a part of parts only of such areas to be subjected to particle erosion. Interesting shading effects are then achievable, particularly with applied colouration, whether by paint or film, say at medial parts of leaf or petal shaped areas, or the opposite which can also be pleasing, say as clear vein formations in leaf-shaped eroded areas.

Generally, part only of each area or sub-area is subjected to erosion in a defined and orderly manner.

Obviously, metal is very resistant to erosion by sand-blasting that needs only low pressure to be highly effective for glass surfaces, and can thus be used a very large number of times, if not virtually indefinitely, as applies to expanded metal with repeating patterns and to metal sheet cut out for erosion to get shading effects. However, it is to be understood that implementation of this invention should not be considered as limited to the use of open-work or selectively cut-out metallic materials, so long as the materials used have a reasonable (not necessarily comparable) working life. For example, it is found that at least some plastics materials are satisfactorily tough and erosion resistant whether available in mesh or perforate sheet form or cut out of sheet to specific aperturing as has been done for differential shading purposes from readily available stiff but thin plastics sheet. Even such cut-out sheet formations can, of course, be from metal sheet, say formed by wire-erosion including of an overall template sheet.

Capability of repeated use leads to another aspect of this invention residing in a template

comprising a substantially flat and form-sustaining member of material resistant to particle erosion and apertured to define desired ornamental erosion, whether as cut-outs for shading erosion or as cut-outs to accommodate erosion-resistant open-work material, whether of mesh or cut-out formation, at the or each position corresponding to a said area or sub-area of glass to be treated.

In one practical template structure for application to flat sheet glass, a sheet of plywood is cut out according to areas including sub-areas to be treated and rebated at edges of each cut-out to take by its edge a desired piece of cut-out or expanded metal or other material preferably having a substantially flat face then substantially flush with one surface of the plywood sheet to be against the sheet of glass during particle erosion. Such a template may be the same overall size as the sheet of glass to be treated, and which will usually be lead-striped later, after particle erosion, but matching sizes is not necessary. Templates could have one or more suction cups for temporary attachment relative to glass sheets, or may be secured to glass by light clamps, say of plastics material, or by adhesive tape, say that well-known as masking tape; and may be positionable as desired, preferably in a

centred manner, i.e. where the template has identified ^' centre lines. It is, of course, also to be understood that template material can be of any nature or type that is reasonably resistant to erosion by glass-eroding particles.

It is also envisaged that a cut-out may correspond to two or more adjacent sub-areas of glass to be treated and divided on the finished glass by ornamental strip, further that open work material patterns or cut-outs be different therefor. Then, pieces of different aperturings can be edge joined together across the cut-out, say by welding (typically spot welding) or soldering for expanded or cut-out metal pieces of different aperture patterns/sizes.

A method aspect of this invention involves the steps of removably associating a re-usable template face-to-face with a glass sheet, subjecting the glass sheet to ornamental selective particle erosion through aperturing of the template at plural areas for enclosure by ornamental strip, and applying ornamental strip to at least one surface of the glass sheet at least surrounding those areas.

Selective use of self-adhesive, tinted or

coloured, at least somewhat transparent flat sheet or film is particularly preferred, and, in conjunction with patterned erosion, can provide effects analagous to different glasses used in traditional leaded lights. Pieces of that flat sheet or film in selected one or more of sub-areas can conveniently underlap lead striping, which distinguishes from one known system in which coloured adhesive film is textured, typically giving a "bubbled" effect, but then makes only interrupted contact with a glass surface to which it is applied. It is considered superior to have substantially full surface contact at least within double glazed units where temperatures can get very high.

Another possibility is to employ chemical etching, say using a patterned re-usable resist, or even a patterned acid-applicator pad and/or a pad and a patterned matrix as an intermediary mask to select etching. Whilst such a process would involve handling acids, and may be slower and less convenient than particle erosion, effects could be comparable, at least on flat glass surfaces.

Product aspects of this invention include sheet glass decorated as above and with ornamental strip on

one or both sides, and matching and registering if on both sides. One-sided striping is usual on glass for cupboards or cabinets where two-sided striping may produce too heavy an effect or its expense cannot be justified) .

Patterned glass sheets, i.e with one deliberately uneven surface, can be particle eroded on the patterned side at least where that has shallow unevenness of its surface, including unevenness that is effectively removed by the particle erosion. Eroded patterned glass surface may even be external of double glazing units made up using this invention, and flat coloured film may be applied to the inner flat surface of such glass.

Glass sheets hereof, preferably lead striped on both sides, find particularly effective and successful use as one element of double glazing, usually the outer.

Practical implementation of embodiments of this invention will now be specifically described, by way of example, with reference to the accompanying drawings, in which:

Figures 1A,B,C show variant designs of leaded decorative glass sheets;

Figures 2A,B,C show plan views of corresponding templates;

Figure 3 is an end view on arrow III of Figure 1A;

Figure 4 is a fragmentary section on line IV-IV of Figure 1A;

Figure 5 is a fragmentary section on line V-V of Figure 2A;

Figure 6 is a fragmentary section on line VI-VI of Figure 2C;

Figure 7 is an enlarged fragment from Figure 2C;

Figure 8 is a detail section for a double glazing unit;

Figure 9 shows sand blasting apparatus;

Figures 10A-I show samples of alternative -metal meshes; and

Figures 11A and 11B show results of imposing shading effects.

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In the drawings, referring first to Figures 1A-C, glass sheets 10A-C have adhered-on lead striping 12A-C in patterns defining various areas bounded by lead strip, or partially bounded if there is no lead strip along edges of the sheet, as is usual. Areas 14A, B,C are indicated as being clear, but areas 16A-C, 18A-C and 20C are indicated as decorated with patterns of differential opacity.

The patterns for areas 16A and 18A are different, as are those for 16B and 18B, and those for 16C and 18C,20C (which happen to be the same but need not be), and the subscripts A and B do not necessarily refer to the same pattern, though they are the same within each one of the sheets 10A-C as a matter of design choice.

Where those patterns of differential opacity are applied by particle erosion, templates 30A-C of Figures 2A-C are used. These templates each comprise a particle-erosion resistent sheet or board 32A-C, for which 10mm plywood has been used in prototypes, having cut-outs 36A-C and 38A,B. The cut-outs 36A-C correspond to the areas 16A-C of Figures 1A-C, actually including the areas 18C, 20C for Figure 1C. The cut¬ outs 38A,B correspond to the areas 18A,B of Figures

1A,B. Each of the cut-outs 36 and 38 has a rebated edge 37 and 39, respectively, and with the same subscript letters to correspond.

The rebates 37A-C serve to accommodate edges of pieces of expanded metal mesh 40A-C, actually four pieces 40C joined together at 41 (conveniently spot- welded), and corresponding to the areas 16A-C of Figures 1A-C. Similarly, the rebates 39A,B also serve to accommodate edges of pieces of expanded metal mesh 42A,B corresponding to the areas 18A,B of Figures 1A,B. Expanded metal mesh 42C corresponding to the sub-area 18C of Figure 1C is wholly within a peripheral edge formed by the mesh pieces 40C and is actually joined thereto, conveniently by spot-welding or soldering using stainless steel type flux as indicated at 44 in Figures 6 and 7.

It will be noted that the mesh pieces 42B each touch one of the mesh pieces 40B in Figure 2B, albeit with underlying rebate about the cut-outs 36B. If desired, these touching mesh parts may also be joined ^' " ^' together, again conveniently by spot-welding or soldering. Otherwise, of course, they may simply be adhered into the rebates, either directly using adhesive on the rebates or by securing with masking tape

extending from the sheet or board 32B, or both if preferred (or in order to protect glass from any risk of being scratched by edges the mesh pieces) . Similar considerations apply to fixing mesh relative to all rebating, i.e. for pieces 40A, 42A of Figure 2A and pieces 40C of Figure 2C. A simple section for one of the strip-bounded areas 18A of Figure 1A, and the corresponding template cut-out 38A of Figure 2A is shown in Figure 3 for the rebate 39A and the mesh piece 42A.

In use, see Figure 9, a template (30) hereof will be associated with a sheet (10) of glass so that rebated surfaces, with which the inset pieces of mesh are substantially flush, are flat on the glass sheet, and the mesh piece will also present a flat surface to the glass sheet. One convenient way to achieve that regardless of orientation of the glass sheet/template assembly is to incorporate one or more suction cups into the thickness of the templates, most conveniently in through-holes, say at a single central position indicated at 50 in Figure 2B or at corners as indicated at 52 in Figure 2B. Suitable- manually operated suction cups are well known. The template (30) may be the same size as the sheet of glass (10), or not, as desired. It can be helpful to indicate centre lines of the template as shown by arrows in Figure 2A.

Alternatively, simple plastic clamps, say of resilient type, may be used to hold the glass onto the template, even simply adhesive masking tape about edges of glass and/or template.

The glass. sheet/template assembly is then subjected to particle erosion, see sand-blasting nozzle 54 indicated diagrammatically in Figure 9 as operated by compressed air in tube 56 to draw in sand from tube 58, and emit an air stream with entrained sand from the nozzle 56. Such a nozzle will apply particles for erosion only through the cut-outs in the template (10) and will produce patterns of erosion complementary to the mesh pattern(s) deployed in those cut-outs, i.e. only through aperturing thereof. Use of low erosion air pressures, typically below 40 psi, say from 15 psi to 60 psi, is highly effective, though higher pressures are not ruled out at least for deeper erosion. Substantial stiffness of installed metal mesh is advantageous in avoiding localised lifting from the glass sheet as might occur for more flexible apertured material, though that is manageable relative to selectively apertured plastics or metal sheet.

Definition for selective erosion can be used to define areas of shading, and then be of other than

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repetitively patterned form. Figures 11A and 11B indicate cut-outs in suitable sheet material, for example of plastics or metal, that is applied to a glass sheet as part of a template, i.e. installed in what would otherwise be an aperture of that template. In fact, Figure 11B shows combination with a central part of expanded metal. After erosion, lead striping is applied as indicated in dashed lines (Figure 11B) or thick full lines (Figure 11A). Basically, Figure 11A shows both selective shading and leaf vein formations and Figure 11B shows just selective shading, but highly contributive to overall effect.

Even sand-blasting by hand, usually in a cabinet with shielded arm entries, glass sheets of Figures 1A-C can be treated in about three minutes or less.

Usually, the glass sheet (10) will be bare of lead strip when particle-eroded, though that may not be essential for the surface not being eroded, (which could even help with positioning of the template/glass sheet) . Ideally, erosion areas corresponding to sub-areas to be divided by lead strip should extend under the lead strip, say to the centre lines of the corresponding strip, see dashed arrow in Figure 4.

Figure 4 also shows lead strip (12) applied to both sides of the glass sheet (10) in registration, and •a thicker line part 11 indicates where tinted or coloured film, or paint, can be applied for colouration effects additional to imposed patterns of differential opacity. It will be appreciated that printed film, particularly of self-adhering type, could achieve effects similar to particle erosion itself.

Turning to Figure 8, part of a double glazing unit 60 is indicated having inner and outer glass sheets 62 and 64, spacer 66 and perimeter seal 68. Usually, it will be the outer shell 64 that is subjected to patterned differential opacity effects, normally on its inner surface, though both surfaces may be leaded as before.

Due to high temperatures that can arise within double glazed units, any colouration would normally be by paint rather than adhered on tinted film. Even so, there is often a tendency for paint to crack and flake, which is not satisfactory for high quality products. Paints that automatically produce a random crazing effect after application tend to be time-consuming and difficult to use, also particularly hazardous to health.

Single surface lead striping will normally find most use in relation to cupboard doors, say of kitchen units or book cases or display cabinets.

A small selection of metal meshes that have been used in various combinations and for various window designs, including those of Figure 1, is indicated in Figure 10.

Extension of template etc. principles hereof, particularly for quite complex designs, say multi-lobed (as for formalised flower designs), can be achieved using adjacently fixed pieces of different pattern meshes, then applying lead strip over the divisions of the resulting erosion on the glass, see Figures 11A and 11B.