Ok
Here’s the deal I airbrushed my roundhouse walls with Model Flex Insignia Red enamel paint one coat waited over night to let it dry.Went to put the motar joints on with testors flat silver enamel paint and the red is coming off too.
One-should I put another coat of red on?
Two-should I dry it with a hair dryer and bake it on?
Three-should I put a coat of dulcoat on the brick let it dry then put my joints over the dulcoat?
Or Four- not put any motor joints on and just have red walls
The red is probably coming off because the thinner in the silver enamel paint is a solvent for the base color. Try using an acyrilic paint for the motar thinned with alcohol. I think the results will be better.
YES. Use polyscale water based paint - and thin it - fot the mortar joints.
Mortar looks white, grey, or black - depending on age and geograpahical location.
Well, you already have been informed about using acrlyic mortar over enamel walls, and enamel mortar over acrylics walls (and, acrlyic over acrylic - as long as the base coat is dried and cured).
However, just having plain walls could work in two situations - modeling a freshly painted building, where the painters have just rollered the paint on the brick walls, covering the mortar (NOT a restoration, where the mortar is restored/repointed and so remains visible), or just a partial coverage on the lower floors (upper floors have the mortar lines), to indicate a fast covering of graffiti - here you want the covering paint to be shinier and cleaner than the base brick color.