I've been trying to solder a pierced sheet,which I first sweat soldered, to a backing.
It starts fine. The solder began to melt, I put it in pickle and then brightened it with a file.
However, on putting it on the backing of 1mm sterling and heating it from underneath, it refuses to melt completely.
It's "stuck" but not completely bonded. I can see light at certain points.
I'm using Auroflux.
I thought perhaps I'd used the solder too thick (even though I had run it through a mill already), so tried again
after beating with a hammer and have the same result (slightly better but not perfect)
As I want to enamel the piece I'm stuck.
What can be the matter?
Any help gratefully received.