Is it necessary to sand and prime the inside of an HO coach before spray painting it black?
I don’t see any reason to, unless you plan on adding the sort of interior detail that can only be appreciated with the roof off.
Assuming the inside is plastic, you might want to sand off any small burrs or casting flash, but once that done, simple washing should suffice before painting.
But, uh, black? Unless this is a very thin-walled model and you’re trying to prevent interior lighting from glowing through the walls, why black? With the possible exception of the Addams Family RR, what prototype would use black?
Yes my question is why black also. Most coaches have either a light brown or tan walls, grey carpet, blue or maroon seats.
Just to further clarify, if the cars are plastic, there is no need to sand. The paint, black, seafoam green or whatever, will stick just fine. Now, if you’re talking brass, then maybe some surface prep to make sure any oil, flux, etc is a good idea, but I’m thinking of a liquid/solvent type cleaner, not sanding.
Sanding would mostly improve the appearance and is not needed for paint prep for a job like this IMO.
Priming? Maybe, but since the inside of the coach won’t be handled, the things that primer does – like promoting adhesion and resisting abrasion – aren’t much of a factor. If it was me, I’d skip priming. With today’s paints, I don’t prime unless there’s a clear benefit to doing so.
Before spraying the inside, mask off the outside of the windows so overspray will not get on the outside of the car.
Passenger cars look so much better with an interior and lighting; here are a few that I have done:
B&M lightweight coach
MEC lightweight coach and lighting
Athearn HW coach before painting
