What enamels do people recommend for plique-a-jour work in
copper and silver? I have some medium expansion opaques in 80 mesh
from Thompson that I was considering using for my first
experiments, but wasn't sure if I needed finer mesh, a mix of
meshes, a different type, etc.
I use well-washed (to remove the fines) transparents for the most
part. I think your medium-expansion enamels are fine, but part of
the charm of plique is the "stained-glass" effect, and that's lost
if you use only opaques; might as well do cloisonne in that case! 80
mesh sounds good; the smaller the particles, the more likely they
are to add cloudiness- of course, with opaques that's not an issue.
I use both leaded and unleaded, sometimes in the same piece- it
might be risky to put them in the same cell, though.
And what's the maximum cell/space size I should limit myself
to? Is there some magic ratio of surface area to thickness?
You'll really have to experiment with your metal, your enamels, your
kiln, etc. Generally smaller cells are less risky than large. I've
had some that filled beautifully, though, while I've had to fight
the glass (with similar specs!) on others. As you work you'll
develop a palette of colors that you like, that work for your
designs, and about which you can predict their behavior.