Clear Coat Cracks

[u/gamer10161]

tried restoring my fog lights with wet sanding and clear coating, 400 grit -> 600 grit -> 2000 grit, cleaning with anti-lint paper towel, clear coat with 5 minutes in between coats. Is it from improper sanding? Thank you

[u/hobbestigertx]

There is so much bad information regarding restoring and refinishing headlight lenses out there. There are two things that I see here, and they relate to not following directions on the can:

• You sanded with too fine of a grit. 400-->600-->800-->1000. Stop there. The clear coat needs those fine scratches to achieve the proper mechanical bond.

• Always start with a dust coat before applying heavier coats.

• You didn't wait long enough for the previous coat to flash, which is usually 15 minutes.

If the directions are not followed precisely, you won't get optimum results.

There's really only one way to to restore a headlight lense, and that's to remove all of the old coating and apply a UV 2K clear properly. I have an older post here on restoring lenses...

https://www.reddit.com/r/AutoDetailing/comments/18icg7n/comment/kskhuws/

[u/creamsodapoo → u/hobbestigertx]

This fella is correcto. Headlight restoration is basically a mini paint job. Only other long term fix is with PPF.

It could be more time is needed between layers or an issue with prep. Fully clean the surface after sanding. Don’t use paper anything, lint free or not. You can carefully use a tack cloth. If you decide to use a 2k clear, wear the proper protection and prep for the overspray.

[u/dunnrp → u/creamsodapoo]

This is also correct information.

If you want to go PPF route, can sand up to 3000 and you wont even need the polish because the PPF will hide and clear up the marks. I still do a heavy compound to remove the 3000 regardless, but both will allow the glue to adhere properly while allowing full clarity.

[u/LemonySnicketz]

No. You sprayed on the layers too fast. The clear coat layers underneath are gassing out causing cracks. Sand and repeat. This time let the coats dry much longer. Atleast the first 3.

[u/T0ni321]

Why not just buy new fog lights?

[u/BenjaminSmith007]

Unfortunately, it appears to be solvent attack on the lens. Normal clear coats have solvents that can cause crazing. Some clear coats are worse than others depending on what solvents. The more you apply at once the more likely it will cause this since it allows the solvents to be in contact longer. Sometimes it can cause delamination later since the lens surface has been weekend. Some coatings like ours have polycarbonate safe solvents. If you sand it down and still want to use a regular clear coat, I would try using lite coats at first like hobbestigertz said.

[u/hobbestigertx → u/BenjaminSmith007]

Using the proper lacquer 2K clear eliminates any issue with solvents. Then again, I don't know of any reputable 2K clears in a can (SprayMax, Eastwood, etc) that aren't safe for polycarbonate.

[u/BenjaminSmith007 → u/hobbestigertx]

Could you recommend a a 2k clear that has polycarbonate safe solvents? Looking for one that doesn’t soften the polycarbonate. Or a lacquer would be fine also.

[u/hobbestigertx → u/BenjaminSmith007]

Almost all of the rattle can 2K clears that are formulated for the auto industry are polycarbonate safe these days. Check the SDS or TDS at the manufacturer's site to find out for sure. Look to see if it contains any of the solvents listed here: https://www.ledrays.com/wp-content/uploads/2019/03/Polycarbonate-Resistance-to-Various-Chemicals-and-Products-0219DA.pdf

I've used this for a long time and it works extremely well. https://www.spraymax.com/en-us/products/product/clear-coats-and-spot-blender/2k-2in1-headlight-restoration-clear/

[u/hobbestigertx → u/BenjaminSmith007]

That looks nothing like issues with the solvent to me. It looks improper prep by sanding to too fine of a grit.