Sealing decals after application?

Acrylic or enamel and or synthetic laquer clear gloss coat used , it's best to use Testore Dullcoat airbrushed at 20 psi .If you can find flat non- spar clear varnish ,it will work better.Thin w/ mineral spirits.

Well I assume you put down a gloss coat to put down the decals ? If you are going to have a flat finish then you would need to apply a flat clear to get rid of the gloss.If you want it shiny then overcoat with gloss just to protect the decals from the weathering process.

Yes.  By that I mean there are a number of overcoats, including clear acrylics, clear enamels and clear lacquers that work well.  The only time I do not overcoat after decaling is over Alclad- I don't like the effect, but decals seem to adhere very well to Alclad, so I leave them be.

Alclad is the only product which when sealed by its own product its "shine" just disappears .