I have a tin of nitrocellulose primer grey is this any good to prime a plug for surfacing? have no experience with autopaints so any insight would be appreciated.
What other primers are out there and what is good to build up a plug for a good moldable finish.
No, nitrocellulose is the worst!
Polyester primers tend to work, some polyurethane primers will. Always do a test if you’re using a new coating, no matter what it is.
Thanks for that info, any reason as to why they are the worst?, and what could I safely use it for as id not like to waste it.
Are 2k paints polyester or urethane and how are they used, also Iv heard of epoxy primer??
Worst would be when your new mould sticks like S%$! to your pattern so much that you need to tear the pattern to pieces with tools while also trying not to do any damage to the new mould gel coat surface, then sanding and sanding until its highly polished and ready to use.
A small mould you might just throw away and start from scratch but a larger mould you would do as above to save it.
I have good results now with a polyester primer.
Like Hanaldo said, test it first or face the worst!
Or even worse when your new mould tears to pieces too
They are the worst because they are single pack and extremely slow drying. It’s very very old technology, nitrocellulose is essentially the first spray paint. It will absolutely react with all chemical release agents, as well as any tooling system containing a solvent like styrene or MEK. It is also quite toxic, as well as potentially explosive. Personally I would throw it away, it’s horrible stuff. That said, you COULD use it to make a mould if you were to use PVA as your release agent and spray it on very thick so there can’t be any reaction between the paint surface and the tooling gelcoat. Or use it to practice your spray painting technique, you could respray a crappy old car or something. Just don’t spray anything that you care about the finish on!
As for 2k paints, they come in a variety of chemical bases from polyester to urethane to polyurethane to epoxy. Just be careful using epoxy, single pack epoxy paints are somewhat more common than two pack epoxy paints, and these are also not suitable for mould making. 2k paints are a spray paint, they are used in exactly the same was as any other spray paint including your nitrocellulose. They are simply resins that require a hardener to cure, but because they have a hardener they do actually cure hard unlike unlike 1k paints which simply dry by solvent evaporation and will always remain ‘soft’.
Polyester or vinyl ester (higher temp) paints like Duratec work well but have a relitivley short shelf life. Auto urethane primers work well and you can use reducers to thin it as necessary. You are looking at $100 plus for Duratec or a urethane.