Painting grp parts

[Chris Lane]

Hi, I have some splendid wheel spats and a cowl moulded in grp. What is the word on finishing these please. I assume a good scrub with warm soapy water to remove any residual release agent is the starting point?

Chris Lane 2938

[John Rickett]

Chris,

Use 240 grade, or therebouts, wet and dry paper to abrade the surface and remove the release agent residue. For best results, change the water a couple of times (and change the wet and dry) to completely wash away any silicone. Using a fairly coarse paper will provide a good surface for painting.

Brush or spray a primer and rub down, again with 240 wet and dry. The plain, matt primer will show up any pin holes and blemishes which can be filled with a stopper - P38 works fine with grp.

Apply further coats of primer and rub down, if you are staisfied with the result, finish with whatever topcoat paint you prefer. If there are still imperfections, repeat the filler/primer step.

[Chris Lane]

John - many thanks for that guidance. I was concerned about the keying of a primer as my previous experience with boat hulls was problematic!

Chris

[John Rickett]

Chris,
I've not had a problem with this method, it possibly depends on which release agent was used. I make most of my own grp parts now using Meguiars release wax and found the parts clean up very quickly. Provided you are careful to thoroughly abrade the surface at the same time as washing off the agent, I'm sure you'll find the primer adheres well. Afew coats off hi-build primer should, when cut back, provide a lovely flat surface for painting.

[Mike Booth]

Highly reccomend you scrub the parts off with acetone or celly thinners first. I would also suggest 400 paper. Sorry to differ John but at 240 if there is any detail on the mouldings it's going to vanish PDQ.

[Phil Clark]

Chris

Another vote for Acetone, this will remove any residue left that water won't remove. (I always Acetone rinse all moulded parts we produce for Jerry Bates)

If the part has moulded detail, abrading with a fine scotch pad also works well.....they are a little less aggressive than wet & dry and being 'soft' they conform to the surface well and don't knock the edge of raised detail as much.

Phil

[Chris Lane]

Unaniminity among the experts - magic! Thanks guys; I have both cellulose thinners and acetone so will use the acetone. Chris