Opti coat over Spar?

[ShineTimeDetail]

Ok, so I was thinking today and I was wondering if you applied spay over opti coat if it would hold up. Here's why I say spar over the opti because I have never seen lights so crystal clear than when doing the spar sealant. I have buffed lights that looked great but never to what spar produces.

I need to be able to offer people at least a 2 year warranty. I bet you could apply opti coat to 50 head lights with one bottle. that would be about a $1 per light. So your at about $2-3 plus the sand paper. I wonder if you sanded up to 2000 if you could get the opti coat to fill like spar does...then you wouldn't need the spar.

Would the opti coat over the spar sealant work?

[ShineTimeDetail]

I think I think to much.

[A-train]

I actually tried to do that with 2500 grit sand marks with opti coat and it didn't work. Just doesnt fill, I too thought it would work.
As for using it over the spar, you would think it would offer more protection but I've never used it.

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[SeaJay's]

Can't say if the Opti-coat over the spar would work or not. I'd suggest going to the junk yard, picking up a headlight and testing it out. Keep it outside for a month or 2 and see how it holds up to some of the conditions. I would think that once the spar hardened you could possibly coat it with no issues. But honestly have no idea.

[Setec Astronomy]

I think I think to much.

I think before you think too much, think about this. As A-Train noted, Opti-Coat doesn't work on a sanded surface. I think you'd get more like 100 headlights out of a syringe. There is a rumor floating about an upcoming Optimum product for "plastic" that came up in a headlight thread here.

[ShineTimeDetail]

So do you think if I polished the light out I'd still get 2 years protection with only opti coat?

[Setec Astronomy]

So do you think if I polished the light out I'd still get 2 years protection with only opti coat?

No. As was stated in another thread, Opti-Coat is not the ideal product for headlights (I got 1 year before I got some yellowing...but there are so many variables), but apparently Dr. G is working on a product for "plastics" which it was implied would perform better on headlights.

My quick take on your idea (Spar first, then Opti-Coat) is that the spar is going to have to fully cure before you apply the Opti-Coat, which means you can't really do that on a "production" basis.

That guy Ray posts in a lot of headlight threads; there are apparently a lot of UV-cure "professional" headlight coatings available, not sure if they really work better than the spar.

[ShineTimeDetail]

Wouldn't a heat gun cure it?

[Setec Astronomy]

Wouldn't a heat gun cure it?

I don't know, I'm not a Spar expert...sometimes you can't force-cure products with heat because you get "solvent pop" for lack of a better description. If you wanted to do it that way, I would look at one of the UV-cure coatings which you can force in 10 minutes with a UV lamp, then Opti-Coat...or wait and see what Dr. G is cooking.

[ray6]

Not sure what you would gain. OptiCoat is a great sealer, but does not block UV. Not having worked directly with the spar method but I would think it seals adequately. The enemy is UV, not moisture in a coated headlight.

I think a second coat of spar would probably double the coating lifetime, but there may be a long cure time between coats. As a general rule, the more UV adsorption material on the headlight, the longer it will last.

For the same reason, the less MS you mix with the spar, the thicker the coating and higher solids content (longer lifetime). Keep in mind that the spar method has a finite lifetime as states clamp down on VOCs, it won't be available anymore. This is why some people can't find it on the shelves. I believe you can no longer buy it anywhere in California. If it were me, I'd start looking for a better coating than spar and learn how to use it now.
ray6

[ray6]

Spar (and most other solvent based coatings) require a 2 step curing process. The first, sometimes called flash or flashing, is the evaporation of the solvents. In the case of spar/MS, it's the MS. This also means the more MS in your mix, the longer the flash time will be and the lower the solids content and shorter lifetime.

I don't think that the spar method will give you 2 years, with or without OptiCoat. I think you'd need a better coating than spar to get 2 years, probably 2K water based and 2 coats.

Once the coating has flashed, the second step begins; with polyurethane (spar) coatings, it is by oxygen adsorption. The oxygen combines with the coating.

You can shorten the first step by increasing the evaporation rate of the solvents with heat, moving air, etc., but there's a limit. You run the risk of skinning, which is the process of forming a sealing top coat with solvents trapped underneath. This is why coatings requiring external energy to cure like IR or UV, will warn you not to cure until coating has flashed.
ray6