Last week I began discussing the new Fast Fire BronzClay (check out last weeks post). I managed to successfully fire my first two batches of Fast Fire BronzClay test pieces. I am excited because the base metal clays can be finicky in their ability to sinter properly. I am hoping that there will be better consistency with this Bronze.?!?
Above, is a photograph of some of the fired bronze pieces next to unfired pieces. It gives a visual of the shrinkage. (I forgot to measure to difference between the pieces in order to determine actual shrinkage).
Directions for firing Fast Fire BronzClay can be found on the BronzClay website (Firing Fast Fire BronzClay).
I fired these bronze pieces in my Paragon FireFly top loading brick kiln. They were placed in a steel pan with activated carbon. I placed a one inch layer of carbon down, then my pieces ensuring there was approximately 1/2 inch space between each piece, then I laid down another 1/2 inch layer of carbon, then a few more pieces, finally I added a top 1/2 inch layer of carbon. The lid was place on top of the pan but it was off centered to allow air to escape. I ramped the kiln full speed to 1525 F then held the pieces at this temperature for 2 hours. Of note: the directions from the manufacturer do not give you an exact firing temperature. They recommend that you test fire pieces at 1525F and then adjust your temperature depending on the results from your kiln (blistering = temperature too high, unsintered clay = temperature not high enough).
Of all the pieces that I fired at 1525 F, I only had only one problem with one piece. Apparently if the firing temperature is too high you will get bubbling or blistering on your pieces. I found this with only one of the 20 plus pieces that I fired. Here is a picture below. The piece on the left has numerous bubbles whereas the piece on the right is completely smooth. It is odd that this only happened on one of the pieces....the only other reason this could happen is if your piece is not completely dry upon firing. I cannot explain this any further....it is what it is.
The final photo below is of the piece with a garnet coloured cz. It turned out fine but if you look closely you can see that there is bronze on the surface of the cz. Apparently I did not clean the surface of the cz...now the bronze is permanently attached to the cz. This is what happens if you don't clean your cz's before firing. To clean them I usually wait until the clay is dry and I will scratch off the clay with a toothpick, then I take cotton swab with rubbing alcohol on it to clean off the rest of the stone. (I guess I skipped this step in my excitement to get things fired!)
About durability of these bronze pieces, they withstood all the banging and bashing I tried!!! I have been unable to break any of the pieces that I have made.
One comment that I have heard it that if you overload your pan when firing or if you do not allow enough space between the pieces then you will run into problems in your firing.
I will keep you up to date about my tests. Next week I hope to post on a patina for Bronze!!!