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Thursday, June 7, 2012

Round 4 of Test Firing Bronze Metal Clay

Round 4…

The set-up…
Media: bronze and copper separately and together, both pieces 6 cards thick
Kiln: top loading brick
Firing Container: round fiber firing container, no lid (phase 2)
Charcoal: coconut shell carbon, acid washed
Phase 1 Firing: Shortened Phase 1 was 25 minutes on a camping stove with a lid (see details below)
Phase 2 Firing: full ramp to 1340 external pyrometer reading (kiln setting 1250), hold for 1 hour

So here we are again, bound and determined.

I decided to try phase one with Hadar’s shortened recommendation (aka “Pre-Firing Phase 1”). Hadar does have a video instruction of this on youtube. There is also a blog entry from her site with instructions/description.

One difference I found (which may have more to do with the fiber box I was using instead of a steel container) is that the instructions/video state it takes 3-5 minutes for the carbon to heat up, at which point you will see smoke (from the binder burning off). It took my set-up 15 minutes before the presence of smoke.

But when the smoke was done (another 5-7 minutes), I checked and my pieces were indeed dark, so I figured I had completed phase 1 (and if this works, it’s WAY better than firing up the kiln, having it on for 2-3 hours, then waiting for it to cool before moving on to phase 2).

And if nothing else, I’ve learned how to use a camping stove. :-P

I decided to do my phase 2 hold time for only 1 hour rather than 2. I have two dinky little people of testing material.

I just wanted to mention, the fiber box lid had a fuzzy side and a non-fuzzy side and I had no way of knowing which way was supposed to face in toward the bowl. Hmph! I probably used the thing upside-down and ruined it, but oh well.

This time my two test pieces are one copper in bronze, the other just bronze, both 6 cards thick.

Here’s what Phase 1 looks like in action.

The pieces are supposed to look dark (but not fire-scale dark) when they are done.

So out of the kiln after phase two, I have two pieces that look seriously less damaged than any of my previous test subjects.

Again, after brushing I did some intense sanding (dremel grinding) and the pieces appear fully sintered… but where did my copper go?

According to Hadar’s instructions (and I hope my interpretations are correct), the fact that the copper/bronze piece is domed (started off level) as well as the fact that my copper disappeared means I’m still over-firing. The pitting is my third clue.

Although the instructions state to lower the temp by 10 degrees for each test, I’ve been lowering the temp by A LOT more than that and am still over-firing so I’ll do like The Price is Right until I get it pretty close.

I haven’t had a test piece yet with indications of under-firing (I’ve had pieces like that so I have a basis for comparison), so I’ll keep lowering for now and keep my fingers crossed.

I *am* happy that the new super fast phase one firing seems to be a thumbs up. Yay!

Anyway, that’s it for now. Will do more testing tomorrow or Satruday.

The last of my toys has arrived (ultralite beehive kiln). After this, the only thing I can/should order for awhile is supplies.

This has been making the rounds on the internet.

I don’t know where it came from or what the story is behind it but isn’t it awesome? If anyone knows the backstory, please let me know. I’d love to find out who the original artist is.

Here is the orchid I was talking about on Facebook

I’m a confessed plant-killer, yet this thing survived (as a stick) through winter and began blooming a couple weeks ago. Yay! I hope I can continue to keep it alive.

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