I'm using setter and softer from Mr. Gunze... and I'm bring it to the decal with ordinary brush square size 6... thats my way
Like putting paint on it... ok... first apllying decal in ordinary way... water, slide it to the model who is before glossed... then with cotton swab dry when I positioned it well... then:
First with brush applyed with setter start from middle till all ends, then in every direction ... up to down, left to right etc...
Like that decal same into panel line, I'm see when I brushing it with setter all air came out and I have put silvering to a minimum.
Whn I done that, i put one more light coat of seter with brush size 2 or 3 and leav it to seter work on decal.
If you see that edges of decal are wrinkled ... dont touch... must be like that, sometimes only edges are like that, somethimes all decal... it will flatten by self very soon... dont look at it, dont touch it... leave it
if somethimes decal didnt came into panel lines... i put on brush another amount of seter and verticali touching decal with brush, expecialy wher is panel... and also like that if I see somehvere silvering...
some modeler stab it with sewing needle, hobby knife... my way is like this... with brush... because I think brushes "hair" are stong enough to penetrate a decal.
And of course when I'm brushing a decal is gently moves...
And another thing, I fgigure this way after many and many decaling process, I see decal befor touching it with brush after first setting procedure... somethimes you cant touch it right away because you will tear it down...
practice, practice...
Hope been helpfull
Roman