Art Clay copper....torch firing

[FVT]

I'm in the early days of trying out the new Art Clay torch-firable copper. While things are definately improving and getting better results each time, I'm still not always confident that something is fired enough.

So, my question is: Does anyone have any good tips for ways to tell if something is fired for long enough? I've had one experience already of drilling a hole in a pendant, which then broke easily into two pieces and was still crumbly on the inside. I don't want to risk breaking everything I make

Thanks in advance

[MuranoSilver]

The only reasonably reliable way is to make test pieces and fire them for the same time (use a timer)
The test piece needs to be of the same thickness as your beautimous piece
Nic x

[FVT]

Thanks for the reply Nic. It's been hard getting opinions on torch firing this new copper clay. Early days I guess. I see what you're saying about making test pieces....but as I am on a tight budget (like most people!) I can't see me making two of everything. So I'm still wondering if there are tell-tale signs on the surface of the fired pieces that give a clue as to whether it's fully fired or not.

Last night I fired a couple of pieces for a second time...and re-pickled and brass-brushed. I am relying mostly on the sound of the piece when I drop it gently onto a ceramic or glass surface...listening out for a certain 'chink' sound!

F.x.

[MuranoSilver]

Nope there are no exterior signs to see whether the piece is fully fired.
The only other alternative would be to drill a hole in an inconspicuous place
(you could always fill n fire it if needed)
Nic xx

[Wendy Moriarty]

Hi
I was told on the pmc begginers course that it has to be kiln fired to be strong enough and that I'd been 'marketed' into thinking I could torch it ( I bought the best torch I coud afford £45 as well), but we did torch fire one piece and it was 2 mins after it started to glow dull peachish red colour, that was silver clay so I don't know if it's the same with other clays. I bought a kiln for mine, I found a little new one on ebay for£140 inc del so I went for it, I don't want to eventually sell something that's not up to scratch. It would be interesting to know if torching is ok or if I've just been marketed again!

[MuranoSilver]

The appropriate answer is that torching can be OK however
in reality the pieces are often underfired as people either dont fire hot enough or long enough.
We were shown fast torch firing once involving a HUGE blowtorch and taking the Silver Clay
to melting point ~ the silver went shiny on the surface (i.e just before melting)
This takes major torch control though and would result in a few melted pieces....

Another (more significant) problem with torch firing is that you're so close to the piece
and most people don't have extraction hoods. Breathing in burn off fumes is not a great idea as
burning metal clay binder is a respiratory irritant

Nic x

[vsilvered]

Nic, I want to thank you so much for this post!

I was beginning to think I was the only person in the UK who believes that torch firing/short firing metal clay is inadequate for producing a durable, stable metal that can be worked just like traditional sheet/wire and that choosing to breathe combustion fumes is unacceptable.