Tuesday, July 13, 2010

The Jury's still out

The bronze pieces came out of the kiln today, but I'm just not sure about them.

Are they metal or not? They sound like metal. They look like metal. (But somewhere I read that some test pieces should be made and tested after firing. I think it said to try to break the bronze pieces with pliers after firing.) Well, I did just that and the test pieces bent and then snapped. I can't break or bend them with my fingers though. And, they didn't disintegrate in the tumbler like my last batch of copper pieces did.

They're not as pretty of a color as I expected either. I fired them in the carbon base charcoal which doesn't produce the colors that the coconut charcoal does but they still should have that buttery gold color I've seen pictures of.

The edges of the pieces that were cut with a tissue blade were fine. The pieces that I cut out with a needle tool were prone to cracking (even though I tried to file them smooth before firing. The book said the cracks would be amplified and they were!) The needle tool tended to drag through the clay, distort the shape and tear the edges. (Again, maybe it was the age of my clay.)

I still don't know if I like this clay or not. I'll give it a couple more tries (with newer clay) before I pass sentencing, but it's not looking too good.


convergentseries said...

Well, Alice, I originally resisted posting a "contrarian's view" on your May 19 entry but, other things being equal, I much prefer cookie cutters (and tissue blades) over templates for exactly the reasons you describe here!

A "compression" cut (whether via cookie cutter or tissue blade) is just going to give you a cleaner cut than is a "drag" action (e.g., needle tool). Easier to smooth while still moist (to reduce/avoid sanding later), as well as being less prone to such cracking along the edge.

(I went back and tried to address the specifics of that earlier post there.)

Re test pieces, Hadar Jacobson doesn't "crash test" (try to break) her pieces any more but, instead, suggests buffing to determine if you've got a sintered piece, or just a sintered crust over a powdery interior. (See for example the last page of her file on firing base metal clays.)

Alice Walkowski said...

Thanks for the direct to Hadar's firing schedule. I've never had much problem with using a needle tool in my silver, but it sure is different in the bronze.