More Bonzclay

I've been working with Bronzclay now since Thanksgiving.  The last pieces are going into the kiln today.  And if none of them have to be refired, I'll be finished with bronze for awhile.

The clay is so nice to work with that I ambitiously made a couple of larger pieces before I realized that bigger, thicker pieces need a different firing schedule. I found some iris pods in the backyard last fall and thought they would make a nice focal piece for a necklace. But the piece I lovingly created turned out to be 13mm thick in the center.

While there is a lot of information about firing this clay out there on the Web,  I decided to contact the manufacturer himself for advice.  Bill Struve was very helpful and patient with all my questions as we exchanged a few emails.

We decided that the slow ramp process Mardel Rein has devised, which takes into consideration the type of kiln, the thickness of the clay, and the target temperature, would be appropriate to try.  So after an initial open air firing phase, ramping at 500° to 650° and holding for 45 minutes, I covered it with carbon and fired at 115° per hour to a target of 1490° and held for 3 hours.  Yes, the piece was in the kiln all day.

One of the pods broke at the seams but otherwise the piece was intact.  It was an easy fix.  The second firing used the same first phase.  But then buried in carbon it was a full ramp to 1510° with another 3 hour hold.  Bill Struve had told me that the slow ramp on already fired items wasn't necessary.

Cleaned up and polished, this was the result.

So what did I learn?
While bronze clay is so much less expensive to purchase than fine silver and I feel compelled to create larger pieces, firing time can cancel out the savings, even when you have solar panels.  So it's not something I will do often.

I'm thinking about digging out my husband's dehydrator.  Some of my smaller/thinner pieces tended to crack or break but they always seemed to be pieces with more than 1 layer and cracks began in the layered area.  It's possible that even pieces that sit around for awhile are not fully dry in the center of the thickest part.  Pieces that sat for a week fired without problems.  Those that were only a couple days old were the ones that cracked.

The shrinkage rate of Bronzclay makes it difficult to create my openwork/filigree designs.  Even when my coils are thicker, they don't seem to stay together.  So I may go back to Goldie Bronze for those designs despite its more grainy finish.

As I stated in an earlier post, bezels need to be attached to already fired pieces and the entire work fired.
 again.  Second firings can be at full ramp to target temperature.

Any pieces with nooks and crannies should be fired in a wire mesh cage.  Because of the shrinkage rate of Bronzclay, this is particularly important.  Small bits of coconut carbon can cause cracks in the design or become embedded in it.

My kiln is a Paragon Firefly and the bonding agent in this clay just would not burn out using the manufacturer instructions.  I had better results using a first phase firing on a kiln shelf then burying the pieces for the second phase.  I do this with both thin and thicker pieces.

Adventures in Bronzclay

I've been working on a custom order for the past week.  The order is for a bronze pendant which came out beautifully and only took 1 day to create.  But I've spent the last 5 days trying to find the proper firing schedule for it.

I made a real rookie error with this order--I created the piece from a product I've never used before.  I've tried and successfully created jewelry from a couple of different bronze clay products.  These were powders that you have to add water to.  Their firing schedules are pretty easy and one is even comparatively short. But I didn't like the final color of one and the other shrank way too much.  But an instructor suggested I try Bronzclay.  It comes already in clay form.  As I was almost out of bronze clay, I ordered 200 grams.

My friend was right.  It's not grainy like one of the powdered products, stays moist longer, and reconstitutes easily.  So right out of the package, after working it a little, I created my custom order.

I also created a couple of test strips and fired them together according to instructions in the package.  The thinner (2mm) strip came out fully sintered but with pinholes.  I'm no expert but I think that means it was over-fired.  The thicker textured strip (3mm) snapped in half when I tried to bend it and the black bonding material was exposed.  What does it mean when the binder burns off on 1 piece but not the other?

I adjusted the schedule a bit and tried again to fire a pair of earrings.  This time the binder didn't burn out on either piece.

What did we do before we had Google and all the information people throw up on the Web?  In my search for sintering problems and firing schedules for Bronzclay I found that I was not alone with my problem. There were no less than 6 different firing schedules put up by metal clay experts that work for them.  Some used a single firing method buried in carbon, some used a 2 step process in carbon, some fired initially on an open shelf then used a 2 step buried-in-carbon schedule.  Others followed the open shelf with a 1 step schedule.  Some schedules were for specific style kilns.  All are very long schedules--easily 9 hours.

After 4 days of trials, the open shelf initial firing to burn out the binder did the trick but the follow up firing caused my next pair of earrings to become brittle and break.  But using a 2-step ramp up and dropping the final temperature some in the second firing seemed to do the trick, at least for the small flower pendant I made.

How you dry the clay may contribute to the problem. It shouldn't be put on a coffee warmer but instead needs to air dry. I found articles suggesting freezing the clay to dry it.

I'm not sure that makes any difference but before I put my custom pendant into the kiln I decided to try a few more pieces to see if I get the same result.  These were also left in the freezer for awhile before firing though I'm not sure why I did that.  They had air dried for a couple days already.

After the successful firing of a few more pieces....

I fired the custom piece.   Voila!!

This bronze product polishes up nicely too.

For those who might be interested, and to add yet another firing schedule to the internet, I achieved this success by placing pieces on an open shelf and a slow ramp of 250°F to 560° F , hold 30 min and cool down.  Then burying pieces in coconut carbon, full ramp to 800°F or 900° F, no hold and ramping at 250°
to 1468°F, hold for 2 hours and cool.  Yes, it's a full day in the kiln.

More Fun with Metal Clay

I've got a half dozen craft show applications sitting in the office, my Etsy shop has been totally neglected, and my website is down pending some new pictures.  So I've been spending a lot of time working on some new silver designs. Wanting to try with silver the techniques I used with bronze clay, I spent another week buried  in my workshop.

Trying to create open work curlicues with silver is a bit different from  bronze.  Silver hardens more quickly and seems to be more fragile when dry.  It breaks more easily.  It took me a while to get used to the feel again so I started with some simpler pieces.

Like flowers and leaves, the curlicues are much easier to put on a solid surface.







But I eventually created a pair of earrings that I really like.

And later a pendant set with a genuine ruby cabochon.

But the best piece I made this past week was actually one I made using a tutorial.  Now there are lots of tutorials out there and they are a great way to learn new techniques.  I just haven't found one for anything I really wanted to try.  But in an older issue of Metal Clay magazine I found a tutorial by Anna Mazon.  She's a metal clay artist and instructor from Poland.  While she's the expert on the open work technique I've been working on, her tutorial is for a 3-dimensional pendant called "Hidden Pearl".  I spent several hours on this piece and I have to say that it's really nice to have all the logistics of the design already figured out.  (Sometimes that takes more time than the design itself.) So I just followed her very clear instructions and pictures and here's the result--

I haven't decided yet if I'll put this one up for sale or just keep it for myself.

Filigree and Curlicues

With a little left of my Goldie Bronze clay I was having a tough time staying away.  I have pages of new ideas for next year and am really anxious to try them out.

Bronze clay is perfect for experiments as it's inexpensive and reconstitutes several times over to a soft,  easily manipulated state.  I've been thinking about filigree and airy designs.  As a self-taught jeweler and no classes around that teach this technique, I got to work on my own.  I rolled a long thin snake and tried to put it onto a clay frame I had made and it just wasn't working.  Wetting the snake to curl it and get it into position just wets the frame and everything eventually gets mushy.  (Put used clay into dish for reconstituting.)

Make new frame.  I don't have a syringe for bronze clay so I turned to my extruder. Using the smallest hole I extracted a snake that was very fine and with a damp brush I formed curlicues on my non-stick surface.  I had drawn out a pattern for the first pair of earrings so I knew the size and shape of the curls I needed.  After letting them dry it was much easier to place them on the frame with a little water to "glue" them on.

The first pair of earrings came out perfect but in my obsessive need for perfection I sanded it too energetically and one broke, not to be repaired.  I did try.  (More clay into the dish for reconstituting.)  And now I have to make the earring again.  But repetition is one way we learn.

I'm now getting better at curling snakes of clay.  After reconstituting the clay in the dish I try another pair of earrings--bigger and trapezoidal in shape.  Well the frame was a bit too big but I figured out that I could attach cross bars of clay to the frame to act as support for my curlicues.  And that worked pretty well as they aren't really noticeable under the filigree.  This larger, more open design was a bit harder and the earrings didn't come out exactly the same.  But I got a lot of practice making curls as I broke a few in the process. (Broken ones in the dish for reconstituting.)

Adding reconstituted clay to the piece I had left I made a large triangular frame for a pendant.  A bigger piece, it needed more support than the earrings so I put a wide bar across the triangle and attached a circle & post for a half drilled pearl.  I wanted to see what random twists and curls would look like.  Using long strings of clay I just let is fall naturally and then used a little water to keep it in place.

Now the big test.  Will these fine filaments of bronze clay survive the high temps of the kiln.  Like any other metal clay, bronze clay shrinks a bit when the bonding agent burns off.  It has to be fired twice in coconut shell carbon--once to burn off the bonding agent and at a higher temp to fuse the bronze particles together.
Fingers crossed I programmed the kiln. And here's the result.  No broken filaments, even after vigorous cleaning.

I'm pretty pleased with my first attempt.  I have a way to go in refining this look.  I know I don't like the randomness of the pendant. I prefer the pattern of the earrings.  And I think less curl might work better if I use more of them.  I'm waiting for another batch of bronze clay and when it arrives I've got a couple more designs I can work on to help me get better at this.