When I lived in Germany,we went on a tour of a sign making factory
(where they made industrially enameled street signs, house numbers
etc...) And when we were done they gave us a bunch of tupperwares
filled with this industrial enamel to experiment with.
The industrial enamel is like a thick suspension of enamel dust in
water. It was fun to work with as it is not so picky, works fast and
makes a thick strong coat. It is also formulated for steel which
makes it an even better solution than traditional enamels.
When we used it, we made our steel piece very clean by attaching a
wire(to hold it) and dunking in some kind of light acid/ cleaner to
get rid of finger oils.
Then we dunked it in the base coat enamel (grey) took it out, hung
it up by the wire, and blew the coating dry with a hairdryer. Then
you cook it in the kiln, take it out and repeat with a colored dunk.
Some people said you don't really need the base coat, but since we
had it, I always used it.
One coating of color should suffice- as it is pretty thick. It has
some really neat qualities- and is fun to experiment with...Colors
are all opaque. Our containers of enamel have lasted for years- you
just add a bit more water now and then.
I was thinking that if you had a local sign shop/ factory in your
area- maybe you could bring some containers over and nicely ask for
a sample. Or maybe Google sign making supply. I always find when it
is jewelry supply- it is more expensive than other industries....