The decal solutions can be used on any matt coat, but that is defeating the purpose of the solutions !
These solvents are designed to soften the decal, to assist in its conforming to the surface, especially into and over engraved detail and raised areas. It then taughtens the decal as it dries, eliminating any trapped air etc, and making the decal blend into the surface as if it's painted on. To do this, the surface needs to be gloss, either gloss paint, such as Xtracolour, or with a gloss clear coat of any prefered gloss clear varnish. Once the decals have been applied, set, and the area cleaned of any deposits or staining, then another clear coat can be applied in the desired finish, that is, gloss, matt, semi-matt etc.
Hopefully, this has answered your question.