[Edit: The information in this posting is obsolete. Stainless Steel Clay is no longer manufactured or supported.]
I have arrived at a more or less reliable firing schedule for the steel clay I was discussing in my previous posting. This schedule works for different thicknesses and sizes, and I will post it soon. In answer to your questions, it was not stainless, and yes, it will rust. To those of you who do not like the corrosion effect, there are ways to seal the steel before you sell it, and ways for the customer to protect it further from corrosion. These ways include bluing, tempering, oiling, and waxing, and I will dedicate a separate posting to this topic.
I did make stainless steel clay. This time the clay is shiny silver in color.
Again, I used a mold that I had made before and pressed the clay against it.
I trimmed off the excess clay,
added a bail,
made test pieces, 4, 6, and 8 cards thick, and started to experiment with the firing schedule.
To avoid oxidation, I fired in carbon, using 2 phases. The first phase was the same as for copper and bronze clay. As for the second phase, at 2100°F (1150°C), test pieces 4 and 6 cards thick sintered, but the 8-card test piece and the pieces I demonstrated above did not sinter completely.
I fired the same pieces for 2 more hours and nothing changed. One thing that I have learned from these experimentations is that re-firing unsintered clay, at least steel clay, does not make any difference.
On a different firing, at 2200°F (1205°C), the steel started to swell and lose details (like blistering on bronze). I guess the next step is to go back to firing at 2100°F, but for more than 3 hours.
Before I do that, though, I’d like to pursue the regular steel. There are two main reasons for this: first, the firing temperature for regular steel is lower than that of stainless steel, although still higher than that of copper and bronze clay, and the firing time is the same. Second, steel clay is cheaper than bronze and copper clay, whereas stainless steel is significantly more expensive. The cost and the long firing hours at high temperatures may make stainless steel nearly as expensive as working with silver clay.
In my next posting I will discuss the firing schedule for steel clay, along with some suggestions for protecting the kiln while firing.