After feeling a bit "burned" by base metal clays a few months ago, I went ahead and tried a new brand on the recommendation of jewelry artist Evelyn Pelati. I went with FastFire BRONZclay by Metal Adventure and was happy with the results for a variety of reasons. Here are a few...
To begin with the obvious, it fires fast. It takes an hour to ramp and an hour to fire. It is a one phase fire, so set the kiln and forget it. I was looking for a base metal clay to use with multiple classes, so I do not always have the luxury of being able to run a multi-phase firing during my teaching schedule. This allows me to not have to return to run a firing on my own time.
There is the other obvious of the price, with bronze clays being around 30 cents a gram and silver clays being more than $2 a gram, it is the most economical, especially for introducing it to a large class.
The firing directions are clear and easy, particularly if this is your first attempt at base metal clays. The descriptions of what you will find out of the kiln and what that means for your firing temperatures are also clear. I was able to figure out my firing schedule after just two test fires, though I have had to make adjustments based on running a whole class worth of pieces at a time.
I have also been able to successfully fire in a ceramic firing vessel. Since I am flip-flopping between silver and bronze, depending on the class, I am running multiple firings a day. When you fire in a steel pan there is a black flake sort of fire scale that needs to be vacuumed from the kiln after your firings. With a ceramic vessel, there is no evidence of the base metal firing.
Last, the workability of the clay has been great. It has a silky flexibility that makes it great for draping and forgiving for students just learning to work with it. When it dries, it is easy to reconstitute and continue working.
These were a couple of quick test pieces where the clay was rolled into scratch foam designs and run through the firing. The bronze has a warm gold hue and nice weight once fully sintered.
Could you share your kiln model and brand of carbon? I tried several firings and am having trouble getting pieces to sinter fully. I am using a paragon sc2 , full ramp to 1525, with one hour hold and some pieces kind of sinter and some do not. Currently have a refire batch in the kiln and tried a two hour hold. Hope to get better results! Thanks!
ReplyDeleteHi Heather,
DeleteI have two Paragon Caldera Kilns (programable/top loading) in my classroom and I use coconut carbon from Art Clay World which I fire in a ceramic vessel made by Square Head (also sold at Art Clay World). Both kilns were bought at the same time and have about the same amount of use, but each kiln fires the BRONZclay at a different temperature, which I discovered when I did test fires for this material.
For my pieces to sinter in one of the kilns, I have to fire between 1550 - 1565, it ramps at that speed and then holds for 1 hour. The temperature changes based on how many pieces I am firing - just 1 or 2 and I have to fire it hotter, a whole class worth and I have to fire it cooler.
My pieces did not sinter in either kiln at 1525, but I followed the directions with the clay for running test strips at 25 degree increments until I could bend them like a "U" without cracking and they did not blister from over-firing. My recommendation is to try some test strips where you ramp at the hold temperature (not Full ramp), where you make the test strips about the size of what you are firing and make sure you look at where you are placing your pieces in the firing chamber. If your kiln is front loading, it may be cooler near the door and you will have to consider that. Also, if you are using a ceramic vessel, you will need to have it up on kiln furniture (not directly on the bottom of the kiln) so that the air travels around it and it heats more evenly.
Also, this post is specific for FastFire BRONZclay (which you can purchase at Rio Grande), I had another brand of base metal clay that I gave up on because I could not get it to successfully fire and could not find anyone else who had. Every brand fires differently.
Good Luck! Marge
Thanks so much! This is great info and I will try some more tests. I had more luck today with a two hour hold time so I will see where that goes. Half the fun of being an artist is problem solving!
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