ASK THE EXPERT - Tom Ellis
Can I use the Thompson lead bearing porcelain Enamel for metal on fused glass 96 coe for fusing or any other glass? if yes, what schedule should I use?
Answer:
Lead bearing enamels have a lower expansion then Lead-free enamels - When selecting enamel colors you must keep in mind that they must be close to the 96 coe or they will crack. There are some colors that could be very close, but you must read the chart. When figuring out which enamel will be compatible, take the Expansion number and divide by 3 and use the enamel that is the closest to the 96 coe. Fire at 1430F until it flows.
Below are the charts. 3 x 96 = 288. So look
for any enamels that have a number of 288 or close to 288 under
'Expansion'. 109 Tr. Lavender is a good example.
Fire to 1430˚F. On the way down, soak at 900˚ for about 1/2 hour,
then let the temp. go down to room temperature.
If you use it on the 96 in very small patches or lines you'll probably be able to get away with it. Try it and then freeze your piece overnight, take it out and let it return to room temp. If the freezing doesn't break it, you're probably OK.
If you fish around, there are all sorts of companies that make enamels for glass to be used on 90 or 96 or float. Fusion Headquarters is a very good company. Also Kaiser has a set of fusible paints for glass. Sometimes you can get sample packs so you have all the colors to play with. Good luck!