for decals to stick on rolling stock and engines is it recommended that they be painted with semi gloss or gloss spray then decal them and spray dull coat sopray?
You want a smooth glossy surface so the decal will adhere good. Several coats of Solvaset or Micro Set will make the decal melt into the painted surface. Wash of the model with clean soapy warm water and rinse to remove any leftover decal adhesive and water stains. A final coat of a ‘flat’ finish like Dullcote should produce good results.
Jim