gel coat

I am wanting to use white hard board paneling 1/8 inch on a boat plug Im finishing, can I spray gelcoat on it? should I sand it first? Also the plug is mostly fiberglass with some bondo, I could use prep tips for the gel coat as it is my first time using it? Thanks

 

I'm not bonafide expert but it the white board is not plastic then I don't know why it wouldn't work - just be sure it is sanded with ~220 or finer. It may take a few coats, each time fairing with smoother paper until you get a smooth fair finish. As far as gel coat over bondo, I'd be sure to seal it first for the best finish. Again, fair the surface as much as possible before you apply the gel coat.

 

1/8" has very little strength, but is easier to bend. It will tend to change shape as humidity changes, so if you plan to fair the surface to a fine and true finish it can change overnight and look totally different the next day.

Bondo and other soft fillers will shrink and change shape at a different rate than the hard board, so expect to see the outlines of the fillers in the mold.

The mold will normally be destroyed in the de-molding process, so don't expect to save it.

Use Duratec sanding primer on the plug, it will work much better than gel coat. I sell similar products but theirs works better.

 

On one off molds I just use PVA or plane old vassoline. I know I'm going to have to sand the part after I get it out of the mold. That thin of board might last a couple of times if your easy on it, finesse it out.