Spar Urethane & Mineral Spirits for headlamp coating

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pixelmonkey

New member
I searched for a thread on the topic at autopia, but have come up short. *If it does exist here, admins feel free to adjust the thread/post as you see fit*



So over the last year, I've been playing with a mix of 50% low odor mineral spirits and 50% High gloss indoor/outdoor spar Urethane



Wet sanding with sand paper to 2000 grit, then cleaning before applying the mix. *if more info is needed, view here*





Anyhow, today I found a kink in the mix. It appears the cleaner Optimum Power clean, when mixed at 3 parts water, 1 part cleaner; is enough to make the urethane mix roll off the lamps like brown water. *looked similar to a bit of root beer pouring from them as I passed the wand of a pressure washer across.



I was seeing a few spots of my truck and wife's car that needed attention. Today, I handed a spray bottle of the 3:1 OPC to my wife and told her to spray the tires, black lower plastic trim and a few other problem spots. She tells me her head lamps are sprayed and she thinks the coating is coming off. Sure enough, it looked like root beer had been poured on the lamps and it was just running off. After I sprayed the front of her car with the pressure washer and it had a bit of time to completely dry, the lamps were back to their previously 2000 grit sanded stage.



The mix was applied last November, before any frost or freezing temps were about.

Cleaning was completed with Diamonite glass cleaner and everything was holding up quite well until the OPC did it's magic.



Just a warning for anyone else out there with the mix on lamps and OPC in the arsenal!

chris<pixelmonkey>:D
 
I would have to believe that concern is one or two things.

First using mineral spirites to thin a urethane, does not allow true catalization to take place, first clue would be before it came off, things started to look a bit "cloudy".

Second, when apply most 1K or 2K urethanes a more "deep" sanding profile is needed.

Usually at a minimum a 220 or a 320 sanding is needed to allow "binding of the urethanes" to the surface.

Been there, done that on some projects using both urethanes.

Grumpy
 
Did you polish the headlights after the 2000, or did you just go straight to the Spar? How many times has the vehicle been washed since then? I just wonder if there was a fluke in your application after the sanding or buffing that caused it not to adhere well. The thread on AG has a gentleman that used the Spar and he had updated pics at 1.5 years that looked just as good as the first day and the car was a 24/7 outside car.
 
My first ap of this mix was done almost a yr ago and no problems so far. I haven't used any Optimum Power Clean directly on them but have used Stoners Tarminator for bug gut removal directly on the lens witrhout any problems so far (knock on wood). I have followed hotrod's thread over on AG and this is the first problem I have seen reported. I do have a mustang cobra headlight that was my test mule, laying out in the shop. I will try some OPC on it directly and see what happens.
 
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