I have used Aura 22 quite successfully, albeit on fine silver,
however when I first used it, I had the same problems you are having.
Here's what I found worked. First, the silver piece must be
absolutely clean with no residue of anything at all on it. I don't
touch the silver with my fingers at all, but use a third hand and
tweezers to hold the piece while painting the Aura 22 on the silver.
I paint on three layers, letting each dry naturally before painting
on the next layer.
The other thing is that I think you are heating the silver too much
(after you painted it with the Aura 22). The silver should only be
heated to about 800 F. Once it reaches that temp, you should
immediately withdraw the heat. Red hot is too hot, in my opinion. I
found that a much lower heat fuses the metals but doesn't alloy them.
Then you let it cool naturally, not by quenching. Then just burnish
or even tumble it and it should come out well.
Aura 22 is delightful when it is properly fused. The pieces I have
prepared in this way have not flaked and have be quite durable.
Hope this is helpful.