Ted here in UK, what your making is in fact a double’ material which
has metals with differential rates of expansion and contraction. you
may know this effect is used in bi metallic thermoucouples.
In your case the thicker layer is pulling the thinner one. result
doming, as you describe, well, to putit at its simplest the thicker
layer is softer, so why not just do what I do is just hammer it
flat. Try it. youll find it will work. All you will be doing is
stretching the softer one.!! cant be simpler.
Obviously use a leather or similar soft faced hammer on a slightly
concave steel block to push it down. As you should know, metals have
a yield point beyond their springyness. You need to achieve this
yield point to move the metal to where you want it.
Ted Who does all metal moving work, ie wrought.
To give you an example one of my minting dies is for a flat key fob
for the little firm from Stuttgart (Mecedes), Nothing to do with them
I may add, just my product. this mints flat but I want it seriously
domed to make it into a button (sterling of course) A suitable piece
of 1in bar, turned to the right profile and a doming block with a
concave depression to match. Then its just a simple hammer job, prior
to fitting/silver brazing of course the back with the omega button
loop to make a hollow button. Front in 1mm silver back.75mm Dont be
afraid to hit it!! Very few on this forum do wrought work, its so
easy and fast.
Let me know how you get on.