Mike.Mara Posted June 10, 2017 Report Share Posted June 10, 2017 OK... Partially through my own impatience I have decided to experiment with making a DIY UV (Sun-cure) finish that we can all use. I have the goal to be able to make it available to everyone here, so hopefully that means even those of you without a compressor and HVLP could use it through a Preval or similar home spray gadget. This might not be possible as getting it thin enough to spray through a Preval might be problematic... But I'll try my best. Anyways... On to the goals: To have a sun cure finish we can all have access to. Not need expensive UV light systems. Preferably with no expensive spray equipment. Cost-effective. (Less than £20 a litre.) Recipe available here for free. (I'm not trying to make any money off this.) The UV cure systems on the market at the moment mostly seem to be made of a polyester base with styrene as the thinner. As any of us who have looked into polyester resins know, you can get an additive to cure it via UV light. So the resin, styrene and UV additive are readily available to all of us in small quantities. This means we can all make these fancy UV cure finishes manufacturers charge in excess of $100 for and without the need for a few hundred pound/dollars of UV light equipment. (Plus the cost of safety gear when using said lights.) A low viscosity polyester resin is my starting point, that way we can avoid the use of too much styrene that would prolong flashing times. (The average seeming to be 15 minutes between coats.) That meaning that with an average (On MSDS and TDS sheets) of three coats, you can have your guitar or other project ready for level sanding and buffing in about an hour. Sounds good right? Now on to the issues I foresee... UV light from the sun on average will only penetrate wood about 80um (0.08MM). So that means unless you feel like the addition of MEKP, we need a sealer. I've toyed with the idea of a seal coat just using polyester resin and MEKP since we know polyester is compatible with itself... This would serve two functions, a grain filler and sealer. It's downfall being that there will be a lot of sanding before you can top coat, and anyone that's sanded polyester knows it's not fun. I'm completely open to ideas on other ways to fill and seal the wood here but with the preference of it curing/drying quickly. So far the starting point will be polyester resin + UV catalyst and around 7% styrene. My research has suggested that 7% is the maximum before we start to affect the polyesters properties when cured. This may make the already low viscosity resin too thin, but I'll adjust it as I go to get the right balance between spray-ability and runs. Although a few minutes in the sun and the runs can be sanded off, so worst case scenario it still beats lacquer. The addition of wax in styrene may be needed to make the final coat cure tack free, but that's a problem for future me. Anyone out there care to chime in? It may be a few weeks before I can buy the supplies to start the experiment so there's a while to discuss possible pitfalls or improvements. Mike. 1 Quote Link to comment Share on other sites More sharing options...
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