SPECTRUM PEARL OPALS
While most glasses manufactured specifically for leadlighting and copper-foiling purposes cannot successfully be fused or slumped, we have slumped the glasses listed here to good effect. The shapes we have found to work well are the single and multiple bridge candleholders, small sushi type plates and small origami bowls.
The Pearl Opals feature a subtle "Corsica" texturing, and may be fired on either the textured or non-textured side.
Obviously, as the glass is only 3 mm thick, and there is only one thickness of glass, any items made are relatively fragile.
Provided the slumping temperatures are kept to about 660-670ºC, the Pearl Opals should not devitrify.
If you are concerned about the possibility of devitrification, products such as Hotline Spray A over-glaze or Borax can be used to prevent devitrification. Not that whilst Hotline Spray A over-glaze is 100% lead free and food-safe Borax is NOT food-safe.
SPECTRUM RED/WHITE TRANSLUCENT
We have successfully fused and slumped one Spectrum glass manufactured specifically for leadlighting and copper-foiling purposes - that is, Spectrum Red/Whit Translucent 357-1S.
If you are seeking to fuse this glass, you should test it first for compatibility. We have found it fuses very well about 750ºC (our kilns). We have observed that the hotter the kiln temperature, the more the colour changes to a dark blood red.