HELP. Did headlights and Spar is cloudy

davidc11291

davidc11291

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I did a headlight job today. Temp was 99 degrees at the time, humidity was 40%. I was working outside in the shade. I mixed my Spar and mineral spirits 50/50, just like always, and applied with a blue shop rag, just like I always do. About 30 seconds to 1 min after I would apply the spar mixture to a section, it started turning splotchy, hazy, and cloudy in random spots. It looks horrible. I'm assuming that the spar was flashing and drying too quickly due to the high air temperature?

If that's the case, do I use more mineral spirits in the mixture, or less? (Dumb question, I know.)

Now that I've covered this lens, how do I fix it? I'm assuming the spar won't come off with a mineral spirits wash? Will I have to sand it off? If so, what kind of grit am I looking at to get it off? Can I get lucky and just hit it with 2000 grit or will I have to go to something more like 1000?

Ugh. And to top it all off, I'm already waaay over my time budget on this detail. I'll be lucky to clear $10 an hr on this job.
 
Yes, it is.
Since the coating is thin, it seems that it should chemically abrade with a solvent that's safe for the plastic.
If not, then surely will sand off. Test spot, least aggressive.
Good luck hand.
 
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Did you wipe down the headlights with alcohol before coating? If you used any sort of polish or patent solution on the headlight and it left a residue, it can contaminate the spar coating.

We don't use the spar method anymore, but did try it years ago. Quickly learned that it was unpredictable and sometimes gave strange results. This coating is very sensitive to moisture, either on the headlight, the applicator or in the coating itself.

Other possible issues are age of the spar, exposure to oxygen (this is how it cures), purity of solvent (mineral spirits), etc. But by far, most common cause of white streaks is water.

As far as the mixing ratio, ideally you would like to use it at 100% to give you the thickest coating possible. The thicker the coating, the longer it will block UV. Problem is, at 100% it sets up too quickly and is difficult to spread into an even coat. Hence you need the solvent (mineral spirits) to thin it down. Also, the more solvent you use, the longer the cure time.

In general, when humidity is low and temperature is high, you would use more solvent.

If you're restoring headlights for money, I have to ask why you are using the spar method in the first place. There are high quality products available specifically made for headlight restoration with predictable results. The actual cost for a good quality coating is probably less than a dollar per headlight.

Also, with most of these coatings, you need not sand any finer than about 1500 grit and should not use any compound or polish. The coating will easily fill in 1500 scratches so the total restoration is faster. Some coatings will cure in less than 5 minutes.

If you want to use the spar method, would try this:

1. Chemically strip off the old coating, or sand off the coating starting with 500 grit, then 1000, then 1500.

2. Scrub with alcohol then apply spar with a dry foam applicator.

3. If it's really hot and dry, go with a 50/50 mix. If you can get by with less solvent, do so. It will give you a thicker coating.

Spar takes about 2 weeks to fully cure.

When you get a bad coat, within about an hour you should be able to remove it with mineral spirits and coat it again. As the coating cures, it will take more effort to remove it, but it should be easy as this is not a very hard coating. Personally, I wouldn't use this method at all. Hard to guarantee your results more than 6 months to a year.
ray6
 
Ray- Thank you for your advice. I've read a big chunk of the spar thread in the past, and your posts always stand out. It's pretty obvious that you've got a lot of technical knowledge about true professional headlight restoration, and the real world experience to go along with that knowledge.

With the spar, I stop sanding at 2000 grit, and I've found that a 50/50 mix will fill in those scratches perfectly.

I hadn't considered a moisture problem. I'm always careful to work surgically clean, and my prep was a ONR wipe down, dry, then a mineral spirits wipe down. My problem may be that I didn't fully dry the lenses after the ONR wipe, or it may be moisture from my sweat- I was dripping wet with sweat at the time.

I'm always careful to keep my spar in a sealed, airtight container, not exposed to air or light, and I never pre-mix a batch, so I don't think its a problem with contaminated spar, but anything is possible.

From reading your posts in the past, I know you're not a fan of spar. I've actually got 1 of your posts saved, where you recommend several different brands of true professional headlight sealants. I've looked into them, and it seems like there's 2 options- either a spray on sealant, or a brush on that has to be cured with a uv light. I've just started my career as a professional detailer, and at this point I'm very much a small time operation, doing mobile work, detailing out of the back of my car. I'm working outdoors, so spraying isn't really practical, plus I just don't like the idea of spraying without masking off the front half of the vehicle. The customer would never know that I got a little overspray on their hood, but I would know. The brush on products are attractive, but spending a few hundred dollars for the sealant and the required uv curing light isn't an expense I can justify right now with the relatively small number of headlights I do. Plus I just don't have any more space in my car to transport the light system, and from what I read from one of your other posts, it seems like the brush on sealants are a little better than spar, but still nowhere near as good as a spray on product.

Is there another product that you could recommend? A brush on product that doesn't have to be UV cured, perhaps?
 
davidc11291 said:
Ray- Thank you for your advice. I've read a big chunk of the spar thread in the past, and your posts always stand out. It's pretty obvious that you've got a lot of technical knowledge about true professional headlight restoration, and the real world experience to go along with that knowledge.

With the spar, I stop sanding at 2000 grit, and I've found that a 50/50 mix will fill in those scratches perfectly.

I hadn't considered a moisture problem. I'm always careful to work surgically clean, and my prep was a ONR wipe down, dry, then a mineral spirits wipe down. My problem may be that I didn't fully dry the lenses after the ONR wipe, or it may be moisture from my sweat- I was dripping wet with sweat at the time.

I'm always careful to keep my spar in a sealed, airtight container, not exposed to air or light, and I never pre-mix a batch, so I don't think its a problem with contaminated spar, but anything is possible.

From reading your posts in the past, I know you're not a fan of spar. I've actually got 1 of your posts saved, where you recommend several different brands of true professional headlight sealants. I've looked into them, and it seems like there's 2 options- either a spray on sealant, or a brush on that has to be cured with a uv light. I've just started my career as a professional detailer, and at this point I'm very much a small time operation, doing mobile work, detailing out of the back of my car. I'm working outdoors, so spraying isn't really practical, plus I just don't like the idea of spraying without masking off the front half of the vehicle. The customer would never know that I got a little overspray on their hood, but I would know. The brush on products are attractive, but spending a few hundred dollars for the sealant and the required uv curing light isn't an expense I can justify right now with the relatively small number of headlights I do. Plus I just don't have any more space in my car to transport the light system, and from what I read from one of your other posts, it seems like the brush on sealants are a little better than spar, but still nowhere near as good as a spray on product.

Is there another product that you could recommend? A brush on product that doesn't have to be UV cured, perhaps?
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Send me a PM.
ray6
 
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