I used to cast small pinecones years ago. What I did to prep them
was to fry them in cooking oil until they quit bubbling, then dry on
paper towels. Sprue them and then vent them from their tops all the
way back to the sprue base. I’d gently blow oxygen from my torch
through the vents to eliminate any ash, which after a thorough
burnout was very minimal to begin with. I’ve thought about trying
this with paraffin used in canning and candle making but was a little
nervous about bringing paraffin to the water boiling point. You want
to get the water out of the item before investing and this is a
relatively easy way to do it.
Have heard there are people firing PMC with a torch
Yes, that can definitely be done, it is preferable to fire in a
kiln.
Hey there Chris
There are lots of metal clay users who sinter the metal clay using a
torch. They seem to be satisfied with the results. I’m still not
convinced that torch-firing results in as fully sintered or as dense
an end product, so, I don’t do it or teach it.
Additionally, the base metals and sterling clay cannot be
torch-fired. And, as far as I know, the 960 silver metal clay (50:50
PMC3+PMC Sterling) cannot be torch-fired. For each of those, a
computer-controlled kiln would be required.
For more on torch-firing you can check out the Yahoo
metal clay Gallery forum and ask your questions about it there.
Hope this is useful info,
Linda Kaye-Moses
Hi Lori et al,
I want to respond to your comments on PMC and torch firing, etc. You
wrote:
Simply put: Torch firing creates BRITTLE pieces.
My reply: My experience with torch-firing is that the pieces are not
brittle, but simply not fully sintered. This creates a fired material
that is not dense enough, weak, fragile, easily broken.
You wrote:
Now that smaller and less expensive kilns are available, it is much easier to properly cure the PMC in the correct environment and create pieces with integrity...
My reply: Metal clay does not “cure”. That implies a chemical
process. The firing of metal clays is a mechanical process called
Sintering. This process involved a dense fusing of the micro-fine
metal particles.
You wrote:
As a polymer artist since 1991, I was anxious to get ingot he PMC world when it was introduced - then I was instructed by my colleagues NOT to use the torch method due to the experiences these PMC jewelers were having.
My reply: Metal clays that could be sintered by torch-firing were
introduced so that users could fire without having to purchase
kilns. It was a way for the manufacturers of metal clays to reach a
wider audience. Unfortunately, I am not satisfied that torch-firing
produces a fully sintered end product.
You wrote:
So I sold all of my PMC. Maybe I will try it again when I can afford a kiln.
My reply: Yes, the kilns are price-y, but they are the efficient way
to fire metal clay. They sometimes become available on ebay or
Craigslist and occasionally they are sold via the metal clay forums,
like Yahoo Metal Clay Gallery.
You wrote:
PMC is NOT as easy to use as the cute little YouTube videos made by kitchen jewelers want you to believe.
My reply: PMC and the other metal clays, Art Clay, BronzClay,
CopprClay, Hadar’s metal clays, Noble, etc. (and there are probably
some I’ve forgotten to mention), are really easy to use. As with any
technique or process, and the use of metal clays is really about
technique and process, the skill to use them requires time spent “at
the bench”, that is, practice, practice, practice.
And demeaning the many carefully produced YouTube videos by
describing them as “cute little…[and] made by kitchen jewelers” is
way off base. There are many who cannot afford to take classes and
there are many teachers of those classes who are quite proficient at
teaching via the online video mode. Yes, there are many amateurish
videos out there, and many quite wonderful ones that teach technique
and process beautifully. There is a difference.
Just a note: I’m typing this reply via the ganoksin website (usually
I reply directly from the emailed forum digest), and I’m noticing
some very odd word processing errors, that I am not creating. I hope
that this reply is readable once Ton or Hanuman post it. If not, I
do apologize for any awkward spacing, etc.
Linda Kaye-Moses
@hans_meevis1 - Sorry to revive such an old thread, but I’m very interested in trying your technique. I have a quick question though. Between pouring the rest of the investment (which I’ve labelled step 3) and drying the mold out (step 4), how much air dry / room temperature curing do you allow?
Thank you!
Jesse.