Talk Composites - The Forum for Advanced Composites

Painting plug for mold making

http://www.talkcomposites.com/Topic32175.aspx

By Coldever - 2/27/2019 5:28:17 PM

I'm making a mold from a cnc-machined mdf plug. I've painted and sanded the plug several times with an epoxy 2K paint and plan to coat it with an acrylic 2k car paint. The mold will be laminated with Easy-composites Uni-Mould Tooling Gel Coat + normal polyester resin on the subsequent layers of glass. I've read that the gasses releasing from the curing paint can cause issues in the gel coat. How can I mitigate that? What's a recommended cure time for a painted surface before I can start on the mold? I'm going to cure the plug in room temperature and can put it in the sauna for a bit if that helps.
By Coldever - 2/28/2019 12:48:58 PM

 
Warren (Staff) - 2/28/2019 10:22:34 AM
If it has been cooked off in an oven then you minimise the risk.  Otherwise you risk the solvent outgassing messing up the release agent.  The safe way is to use PVA mould release agent, although it does not give a perfect surface finish.

Alternatively, ditch the paint idea and use the pattern coat primer and high gloss system to get a smooth finish which will be fine to release the Uni-mould system from.

Thanks for the help! I want to use the paint because I already have it purchased and prefer to spray it on rather than brush, as my plug is labouros to sand because of it's shape.

I guess I'll leave the paint to cure for a few weeks (?) and then put it into 40 degrees for a while to speed up the curing some more. I plan to use the EasyLease + wax. I can try the gelcoat on a test piece first.