GB2491172A - Method of producing an image using glass - Google Patents

Abstract

A method of producing an image using glass, comprises providing an engravable substrate 1, engraving a desired image on the substrate to provide a mould (3), providing glass fit of one or more desired colours, applying glass fit of the desired colour to at least one desired area of the mould 4, and then applying a float glass layer over the surface area of the mould to form a prepared workpiece. The float glass layer is a clear glass frit. The prepared workpiece is then fired in a kiln for a desired period at a temperature in the range from about 825-835C, which fuses the fit and float glass and provides a coloured glass image (6). The fired workpiece is then removed from the kiln and the mould separated. The mould may be formed from a Plaster of Paris substrate and the image formed on the substrate by tracing the image and forming by hand or by laser etching.

Description

A GlasLProduCt The invention relates to a glass product and particularly to a method of producing an image using glass.

Glass has traditionally been used for decorative purposes, particularly in coloured glass windows often seen in churches, cathedrals and dwellings. Such decorative glass is usually formed by painting directly onto glass, or by staining. However, such glass is usually relatively thin, and is thus fragile. Moreover, despite the skill of makers of such glass, there is generally a limit to the degree of detail in any given image which can usefully be achieved.

It is therefore an object of the invention to seek to mitigate these disadvantages.

According to the invention there is provided a method of producing an image using glass, comprising the steps of providing an engravable substrate, engraving a desired image on the substrate to provide a mould, providing glass frit of one or more desired colours, applying glass frit of the desired colour to at least one desired area of the mould, then applying a fusible glass over the surface area of the mould to form a prepared workpiece, firing the prepared workpiece in a kiln for a desired period at a temperature in the range from about 825-835C, whereby to fuse the frit and glass and provide a coloured glass image, removing the fired workpiece from the kiln and separating the mould and the produced coloured glass image The fusible glass may be any kind of fusible glass, such as float glass.

Using the invention it is possible to provide the image as a product such as a glass panel or plate having a thickness which has a self-supporting strength and which has an image of one or more colours permanently fused into it as an integral part of the panel or plate. The thickness is suitably in a preferred range of 2-6mm, though it could be greater than 6mm in appropriate cases.

It will be understood too that using the method engraving the substrate generally involves the practise of incising the image, or design, in the surface of the substrate (which is usually flat), incision being by use of a suitable tool such as a burin. Alternatively, engraving may be effected using a laser etching technique to form the mould. When using laser etching, the substrate can be relatively thin and is also relatively harder than a relatively soft substrate that is used for larger images. Further, the glass may be etched to form a mould by laser etching, and then the etched area (s) may be filled with glass (es) of a desired colour.

Whichever etching technique is used, the substrate is generally a plaster substrate, for example Plaster of Paris, which is preferably dampened during etching.

The separation of the mould and the produced coloured glass image after firing may suitably be achieved by breaking the mould and removing it from the glass.

A method of producing an image using glass embodying the invention is hereinafter described, by way of example, with reference to the accompanying drawings.

Figs 1A to iF show steps in the method according to the invention; Fig 2 is an enlarged view of Fig ID; Fig 3 is an enlarged view of Fig iF; Fig 4 shows the workpiece after firing.

Referring to the drawings, there is shown a method of producing an image using glass, comprising the steps of providing an engravable substrate 1, engraving a desired image 2 on the substrate to provide a mould 3, providing glass frit of one or more desired colours, applying glass frit of the desired colour to at least one desired area 4 of the mould 3, then applying a float glass sheet 5 over the surface area of the mould 3 to form a prepared workpiece, firing the prepared workpiece in a kiln for a desired period at a temperature in the range from about 825-835C, whereby to fuse the frit and float glass and provide a coloured glass image 6, removing the fired workpiece from the kiln and separating the mould 3 and the produced coloured glass image 6.

In the drawings, the image to be produced in glass is that of a historical map of London of the mid-sixteenth-seventeenth century, the river Thames being shown at 7 and being formed in the substrate 1 of Plaster of Paris by being etched to a greater depth than that of the city 8, details of which are shown in Figs 1D to iF, and Fig 2. As can be seen in Fig IA, there is provided a sheet of tracing paper 9 which bears the outline of the map of the city and which is pressed into the substrate 1 (FigiB), which substrate is a relatively thick and relatively soft platen or block of Plaster of Paris. After pressing the tracing paper onto the surface of the substrate, the outline of the image is traced onto that surface1the tracing paper is then removed and the image 2 is engraved into the flat surface of the substrate (FigiC) using a burin tool. Additional detail can if desired then be engraved directly by hand within or to supplement the basic image derived from the tracing paper. In the embodiment a cartouche 10 is formed (Figs 1E and iF) in which a description or history 11 is inserted as by screen printing (Fig 1G).

As shown in Figs 1D,E and F and 2, the parts of the mould 3 formed by engraving the surface of the substrate 1 are filled with glass frit, different colours being used as desired for different parts, for example black for the image 4, depicting streets of the city, and blue depicting the river Thames 7.

The glass frit is a crystal glass frit, in the embodiment a crystal low iron float glass. It will be understood that only one colour may be used if desired, for example black frit powder.

After applying the glass tnt as described above, a float of relatively clear glass frit 5, about 6mm thick, is applied to cover the coloured glass tnt and any screen printing applied to the mould 3. The mould with the float glass sheet is then placed in a kiln (not shown) and fired using a sequence of times and temperatures as described below. After firing, and cooling, the plaster of the mould 3 is cracked and crizzled as clearly shown at the numeral 12 in Fig 4.

The mould and formed coloured image 6 are then separated by breaking the cracked and crizzled mould 3 away from the image, which is a single coloured glass plate with a clear cover formed by the covering layer of clear glass sheet. It will be understood that during firing, the coloured glass tnt and the covering layer of clear glass sheet slump to take the shape of the mould formed in the engraved surface of the substrate i.e. by a tack fuse plus slump process.

In a firing sequence for producing the glass product shown in the embodiment, the temperature is first raised from ambient tp about 60C; then the temperature is raised from about 60C to about 600C over a period of about 2 hours and 20 minutes, and the temperature from 600C to about 835C, the temperature rise from about 15CC to about 835C within the aforesaid range taking about 30 minutes in the 2 hour 20 minute time period mentioned. The temperature is then allowed to fall from about 835C to about SIOC over a period of about one hour. The final step is then to lower the temperature to about SOC with no annealing time, the firing sequence then being completed to provide the product as shown in Fig 4.

The firing sequence can be modified. For example in a modification the firing temperature is raised about 100C per hour to about 520C at which the product is held for about 30 minutes. The temperature is then raised at about isoc per hour to about 820C at which the product is held for about 30 minutes. The temperature is then allowed to fall from the maximum to about 540C which is held for about 20 minutes. The temperature is then reduced at about 1OC per hour to SlüC and held there for about 20 minutes then allowed to fall at about 100C per hour to SOC when the firing sequence is ended.

It will be understood that using the method described herein with reference to the drawings, a single plate of coloured glass product 6 is produced to form a final product bearing the desired image, the colour being formed by fused glass frit and covered by a clear, or at least translucent, layer of float glass. The image is thus an integral part of the final glass product.

It will be understood too that the invention extends to the final glass product per se which can be used for display or decorative purposes by being incorporated in or on a surface to provide a screen, partition, balustrade, or wall installation, as for example by being mounted by any suitable means such as in a frame.

It will be understood too that the term frit' used herein generally refers to glass powders.

Claims (11)

1. LI-Claims 1. A method of producing an image using glass, comprising the steps of providing an engravable substrate, engraving a desired image on the substrate to provide a mould, providing glass frit of one or more desired colours, applying glass frit of the desired colour to at least one desired area of the mould, then applying a fusible glass over the surface area of the mould to form a prepared workpiece, firing the prepared workpiece in a kiln for a desired period at a temperature in the range from about 825C-835C, whereby to fuse the frit and float glass and provide a coloured glass image, removing the fired workpiece from the kiln and separating the mould and the produced coloured glass image.
2. 2. A method according to claim 1, the substrate comprising a block or platen of plaster such as Plaster of Paris.
3. 3. A method according to claim 1 or claim 2, the step of engraving the image on the substrate comprising applying a sheet of tracing paper carrying the image to be produced, pressing the tracing paper into the substrate and tracing around the image to reproduce it on the substrate.
4. 4. A method according to claim 1 or 2, the image being formed freehand directly on the substrate.
5. 5. A method according to claim 1 or 2, the image being formed on the substrate by laser etching.
6. 6. A method according to claim 3 or 4, the substrate being dampened during etching.
7. 7. A method according to any preceding claim, the fusible glass frit comprising a float glass.
8. 8. A method according to claim 7, the float glass comprising a relatively clear glass frit applied to a depth of about 4-8mm, suitably 6mm.
9. 9. A method according to any of the claims 3-8, comprising adding additional image detail freehand after tracing around the image carried by the tracing paper.
10. 10. A method according to any preceding claim, including screen printing part of the image.
11. 11. A method of producing an image using glass substantially as herein described with reference to the accompanying drawings.