From Ritu Sangal, India
I fired flux on copper and then did silver cloisonne and fired. On firing the wires towards the inside of the kiln melted and I can see the copper as the flux has got displaced. Most of the other wires are fine. How an I STONE/ REMOVE the alloy thus formed. I Want to salvage the piece as a lot of work has been done. Thank You
I do not have the answer to your problem, but I can tell you the reason why it happens, so that in future you can avoid. while firing silver on copper, if silver touches the copper at the base it immediately starts burning, to avoid this you can use high fire flux, (which is not available in India) or fire a little lower temp and for a little short time so that flux don't get time to melt more to allow silver get sink. You can use translucent enamel in place of flux which melts at higher temp, It is transparent at high temp. but milky at normal firing but gives good results.
Hi,
here an additive tip: So as Trish wrote, you can try to remove the mistakes with diamond milling cutters. But! if the work is not from precious metal it is mostly more effective if you make the whole work new. Especially if you use transparent enamels, the defects often remain visible.
If you use silver wire over copper-ground, apply at first a not to thin medium flux over the copper-surface and fire it. After cooling, grind the enamelled surface lightly with diamond- or carborundum tools. On this slightly rough surface the cloisonné wires dont slip if you glue it onto the flux surface. If all wires is got glued, spray a thin layer of holding agent over the work and sieve on a very thin layer of flux. After drying, fire the piece carefully. Remove it from the kiln as soon as the surface is shiny.
edmund
I fired the piece again and managed to melt a couple of more silver wires. The wires which melted were towards the inside of the kiln. The piece was completely ruined. I was at a loss as I have done this previously with no problem. On having my kiln checked, it turned out that my temperature meter was not working and so the kiln had uneven temperature?? Just my logic!
So as Rudolf wrote you can apply at first a shift of flux and then fire silver foil over it. That prevents, that the silver wires in contact comes with the copper surface. If Silver comes by temperature around 750 or more degrees Celsius in contact with the copper arises an alloy with a melting point much lower than the silver or the copper melting point.
If it is not really required to use silver wire, and if you do not want to use copper wire because of the copper-tinder, 85/15 Tombak-alloy wire is a very good alternative. The wire has a beautiful gold color and it forms only a very thin shift of tinder. This tinder must not be removed before the following firing, because it is very stable and don't jump-of by the next firing. After grinding and polishing the wire surface looks like gold and it keeps for a long time his golden shine, very many longer than copper. Tombak 85/15 is an alloy of 85% Copper and 15% Zink.
But don't use it on a Silver underground. That makes the same problems as silver wire above copper.
Thank you Edmund for your time and input. I think my problem arose because of the difference of temperature between the inner side and the outer side of my kiln chamber. My kiln chamber size is 6 x 6 x 14 inches deep, because in both the firing episodes the silver wires towards the inside melted completely. The wires on the the piece towards the door were absolutely fine. Thanks to all your inputs and my following all the tips I realized that I need to check my kiln. My kiln has been repaired now. So I should start some new project soon