brittle silver after pmc use
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Original Post
Help. i made two pendants out of silver pmc and then thouroughly dried them and fired them with a torch. they were thick as i intended. but then cracked into three pieces when i applied pressure. what did i do wrong?????????? is it bad pmc or bad technique?
Posted at 10:11pm Aug 12, 2008 EDT
Responses
Torch firing is very tricky. Ideally the silver should be heated to beween 1500 and 1600 degrees for 30-60 min. You just can't quite get that with a torch.
The best you can do is to try to fire them for longer, getting them nearly melting, without actually melting them. It's kind of tough.
Posted at 10:23pm Aug 12, 2008 EDT
Yikes. I only torch fire (the one meant for torch firing) and have not had problems. Are you sure you torched them long enough, and they were really all the way dry?
Posted at 12:09am Aug 13, 2008 EDT
You didnt fire them hot or long enough. The clay didnt burn off and the metal didnt bind together.
I didnt want to invest in a kiln and so I purchased the Speed Fire Cone System. It's a $150 investment but well worth the ability to fire with more control than just torch fire. I saw much better results after using it.
Posted at 12:20am Aug 13, 2008 EDT
It happened to one of my pieces as well. How about firing it couple of times? Would that help?
Posted at 10:56pm Sep 3, 2008 EDT
I think it has to be PMC3 to torch fire, and take it to peachy orange, then hold it at peachy orange for at least 3 minutes. I have used a kitchen timer for that. I also torch it in a very dark room so I can see the color change. I haven't had one break yet, but knock on wood...
Posted at 11:01pm Sep 3, 2008 EDT
Can you over fire it?
If you fire it twice would it make it sronger?
Do any of you know the answers to these 2 questions?
Posted at 11:27pm Sep 3, 2008 EDT
If it broke into pieces that means it wasn't heated thoroughly to the core of the piece for the metal to fuse. Torch firing is tricky.
Posted at 11:40pm Sep 3, 2008 EDT
It seems like I remember my instructor saying that it can be overfired but it would melt? Does that sound right? I always just followed the instructor's directions (even in my own kitchen) because the clay is too pricey for me to waste.
I never had a problem using a butane torch on PMC3, and I even set sterling bezel cups in the clay and fired that too.
I know it's not much info, but I hope it helps!
Posted at 11:43pm Sep 3, 2008 EDT