Monday, September 19, 2011

Copper and Bronze clay




     As was mentioned in my previous post, I've revisited working with copper and bronze clay.... via Hadar Jacobson's powdered clays.

     A little over a week ago several of my friends and I had a play day to try out the clay. Ginnie Weltner, who is a frequent student and friend and my college roommate, Cindi Armstrong  (who visits every Labor Day weekend and is a once a year student) helped me test out the powdered clays.

     We each mixed our own clay and tried Hadar's "inlay" technique which is one of the first projects in her most recent book, Pattens of Color in Metal Clay; Canes, Gradients and Mokume-Gane.   My friend Carol Scheftic has a photo of two of her pieces in Hadar's book.  One of them is the inlay project.  The book is worth checking out.

     The inlay project is made by rolling the copper clay to the thickness of two popsicle sticks, impressing a deep texture or object into the clay, filling the depression with the bronze clay and sanding the piece to expose both of the clays in a level surface.  (Now I know that my description is not very detailed and it's not meant to be.  For more detail, check out Hadar's book.)

     For the most part it's not working with the clay that stresses people out but the firing process, which I'll talk about in another post.   Luckily, both my test piece and the final pieces fired successfully at the recommended temperatures.  

     The only thing I noticed was that the bronze appeared to be more porous looking and had small cracks in it.  (It wasn't the same in all the pieces which could be attributed to us each mixing the bronze clay differently.)  I also know  I wasn't as careful mixing the bronze as I was the copper and felt that we all had it a little drier than it should have been.  (Another learning experience!)  We could repair the cracks and re-fire the pieces.  (Which we don't plan on doing as they were very small.)

     The final step was to apply Baldwin's Patina to the highly polished and cleaned pieces.  Baldwin's Patina is specially formulated to work on copper and bronze.  I found it worked best when the piece was warmed up in very warm water.  (Otherwise the clay just seemed to suck the patina right in.  It didn't do that in the video!  Hadar's blog offers a video on how to apply the patina.)   The patina highlights the contrast between the copper and the bronze.

     So far, the only thing I do not like about using the bronze and copper clays is that they are very dirty to work with.  Using liquid gloves does help keep the hands cleaner, but somehow the darn stuff manages to still get under the fingernails and the dark dust is everywhere.

     I have several other pieces ready to be fired before I decide for sure whether I like this clay or not.  They all use the drape method and will be much lighter in weight than the inlay pieces.  I'll keep you posted.

1 comment:

convergentseries said...

Oooh, lovely! Several quick thoughts:

The "more porous looking" and some of the cracking could well be due to insufficient mixing/rolling/kneading and/or to insufficient moisture. Hadar's clays should just feel soft and smooth and wonderful as you work with them!

And, one of the reasons one wants to use a deep texture is to permit sanding pieces down more, both pre- and post-firing, to smooth out surface cracks without losing detail on the texture. (You typically sand way more than I do, so you should be able to "get" this quickly! It's the one aspect of this particular approach that I really keep wanting to resist.)

Another aspect of cracking has to do with varying shrinkage rates. I did post a little bit about shrinkage-cracks and tried to show a few of my final results.

Maybe that's something we can explore next time we get together? In the meantime, of course, I hope that Ginnie, Cindi, and you are all pleased with these new treats!