Glass for Object Wheels: Stained, Fused and Lampworked
Updated: 2 days ago
By Rocco (Roi) Ramon - licensed architect, founder of Studio Yabaye
A kaleidoscope wheel is a filter. Light enters from behind, passes through the coloured material in the disc, and the mirrors repeat what comes out. The mirrors add symmetry only. Colour, texture and every edge in the image are set by the material of the wheel.
This article is a general survey of the glass techniques used by kaleidoscope makers at large: sheet glass joined with lead or copper foil, kiln-fused glass, lampworked rods and beads, and frit and stringers. My own wheels are made differently, and I describe them once, near the end. How a wheel moves and how several wheels combine is covered in how rotating wheels change the image.
How glass gets its colour
The colour of glass comes from small amounts of metals and metal compounds in the melt. Each one absorbs part of the spectrum, and the glass transmits the rest.
Cobalt. Gives blue. Concentrations of 0.025 to 0.1 percent are reported as enough for blue glass.
Copper. About 2 to 3 percent copper oxide gives turquoise. Pure metallic copper gives a very dark red, opaque glass.
Manganese. In higher concentrations it gives an amethyst colour.
Gold. Metallic gold at around 0.001 percent gives ruby red.
Cadmium and selenium. Cadmium sulfide gives deep yellow. Together with selenium it gives the red known as selenium ruby.
Iron and chromium. Iron oxide gives bluish-green. Chromium gives dark green.
Depth of colour depends on thickness: the same glass reads darker when the light has more of it to cross. Some glasses are striking colours. Bullseye Glass describes them as glasses that look pale or colourless as cold sheet and develop a much different colour when fired.
Transparent and opalescent glass
Transparent glass lets light pass in a straight line. Opalescent glass scatters light, so it looks milky. The Corning Museum of Glass describes opal glass as translucent and white, with a greyish or bluish tinge.
The mirror system works with light that travels along the tube. A transparent element sends its filtered light straight toward the mirrors. An opalescent element scatters the same light, so less of it continues along the tube. The element reads darker and less saturated than the same colour in transparent glass.
What to check: hold the wheel toward a bright window, without the instrument. Elements that let you see the window frame through them are transparent. Elements that glow evenly and hide the frame are opalescent.
Sheet glass, cut and joined with lead or copper foil
This is the stained glass method. The Corning Museum of Glass defines stained glass as the generic name for decorative windows made of pieces of coloured glass fitted into cames. In a wheel, flat sheets of coloured glass are cut to shape and joined along their edges with metal.
Lead came. Came is a metal strip with an H-shaped or U-shaped cross section that holds the edges of the glass. Lead is the traditional metal because it is soft and flexible. Zinc is more rigid.
Copper foil. The edge of each piece is wrapped in adhesive copper tape, and the pieces are soldered together along the taped edges. Sanford Bray patented a method of this kind, "Joining Glass Mosaics", in 1886.
Edges in the image. Every joint is an opaque metal line. The mirrors repeat these lines as a dark network.
Fused glass and the question of compatibility
In fusing, pieces of glass are stacked and heated in a kiln until they bond into one piece.
The condition for a sound result is that the glasses are compatible. If two glasses fused together contract by different amounts, stress stays locked in the piece, and it can crack. The figure usually quoted is the coefficient of expansion, COE. Fusing glass is commonly sold under a COE label, most often 90 or 96, and makers keep to one family in one piece.
The COE number is a simplification. Bullseye Glass states in its technical notes that matching COE numbers is not an accurate measure of compatibility. It adds that the viscosity characteristics of a glass are equally important as its expansion characteristics. Its own test fuses small chips to a base sheet and views the cooled sample for stress through cross-polarised light.
After fusing, the piece is annealed: cooled in a controlled way so that the surface and the interior cool uniformly and internal stress is relieved.
Edges in the image. A full fuse softens the edges and the colour boundaries. A lower-temperature fuse keeps relief on the surface.
Lampworked rods and beads
The Corning Museum of Glass defines flameworking as forming objects from rods and tubes of glass that are softened in a flame and shaped. Lampworking is the older name, from the oil lamps once used. Today the heat source is a gas torch.
Lampworkers use soda-lime and lead glasses, called soft glass, and borosilicate glass, called hard glass. Soft glass expands and contracts much more than borosilicate: soft lampwork rod is commonly labelled COE 104, and borosilicate COE 33. The compatibility rule of fusing applies here too, and the finished piece is annealed.
Light and colour. A lampworked element is three-dimensional. A transparent rod or bead refracts light like a small lens.
Edges in the image. Outlines are curved and continuous. Twisted canes carry fine lines of colour, which the mirrors repeat as line patterns. Curved forms and twisted glass are also the objects Brewster favoured in 1858, as summarised in what goes in a kaleidoscope object cell.
Frit and stringers
Frit is crushed glass. Bullseye sells it in five grades, from powder at 0.2 mm and finer up to extra large granules of 5.2 to 30 mm. Stringers are thin drawn threads of glass. Both are fused onto a base sheet or picked up on hot glass at the torch.
In the image, frit gives a granular texture with many small edges and no dominant line. Stringers give single fine lines.
A separate case is glass coloured by a thin-film coating, not by the melt. It is covered in dichroic glass: colour from interference.
What goes into my wheels
My wheels do not come from any one of the techniques above. Every Studio Yabaye object wheel is cast in crystal-clear resin, holding coloured elements. I pour and compose each wheel by hand, so no two pieces are alike. The coloured elements include:
beads, glass stones, sequins and glitter
stones and simple gemstones
shells, charms and pendants
brass rings in several sizes
liquid and powder pigments
threads and shavings
leaves, plants and dried flowers
Everything in the wheel is fixed. Only the wheels themselves rotate. The wheel axle is mounted directly beside the mirror system. The range includes two-wheel and three-wheel models.
Checklist: reading the material in a wheel
Are most of the coloured elements transparent, not opalescent?
In direct, strong light, does each transparent element show colour, not a dark shape?
With two or three wheels, do the overlaps still transmit light?
A kaleidoscope needs direct, preferably strong light. Aim the far end of the tube at a bright window or a strong lamp, never at the sun.
FAQ
What is in a kaleidoscope wheel?
A kaleidoscope wheel is a disc carrying coloured elements that the mirrors repeat. Across the craft, wheels are made from cut sheet glass joined with lead or copper foil, kiln-fused glass, lampworked elements, frit and stringers. A Studio Yabaye wheel is cast in crystal-clear resin, holding coloured elements, poured and composed by hand, with everything in it fixed.
What is a stained glass kaleidoscope wheel?
It is a wheel assembled from pieces of flat coloured sheet glass, cut to shape and joined along their edges with H-shaped lead came or with copper foil and solder. The metal joints are opaque, so they appear in the image as a network of dark lines.
Why does opalescent glass look dark in a kaleidoscope?
Opalescent glass scatters light inside the glass, which is why it looks milky. A kaleidoscope works with light travelling along the tube. Transparent glass passes that light straight toward the mirrors. Opalescent glass redirects part of it, so the element reads darker and less saturated than the same colour in transparent glass.
What does COE mean for fused glass?
COE is the coefficient of expansion, a measure of how much a glass expands when heated. Fusing glass is commonly labelled 90 or 96. Glasses fused together must contract alike on cooling, or stress remains. Bullseye Glass states that matching COE numbers is not an accurate measure of compatibility.
What gives kaleidoscope glass its colour?
Metals and metal compounds in the melt. Cobalt gives blue at concentrations of 0.025 to 0.1 percent. Copper oxide at 2 to 3 percent gives turquoise. Manganese gives amethyst. Gold at about 0.001 percent gives ruby red. Cadmium sulfide gives deep yellow, and with selenium it gives the red called selenium ruby.
What is lampworked glass in a kaleidoscope?
Lampworking, also called flameworking, is forming rods and tubes of glass that are softened in a flame, today a gas torch. For kaleidoscopes it produces beads and twisted canes. Each element has curved outlines, and a twisted cane carries fine lines of colour that the mirrors repeat.
About Studio Yabaye
Studio Yabaye builds kaleidoscopes and teleidoscopes with front-surface mirror systems in several configurations, in a brass tube, cut, fitted and hand-finished in the studio. Each object wheel is cast in crystal-clear resin, holding coloured elements, and is poured and composed by hand, so no two pieces are alike. The studio is based in Israel and ships worldwide. The current range is at all products, and questions can be sent through the contact page.
Comments