Cleaning headlights - 100% IPA dissolves plastic?

Cleaning headlights - 100% IPA dissolves plastic?

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V8S

Original Poster:

8,582 posts

237 months

Thursday 9th June 2016
quotequote all
Hi all,

I'm breaking a car and have taken the plastic headlights off to sell. They were milky with oxidisation so I wanted to clean them up.

After wet sanding with 800 and 1200 grit, I have washed and cleaned and washed and cleaned repeatedly to remove any plastic residue.

The next stage is to go over it with isopropyl alcohol to remove any contaminants. I bought 100% IPA, not the 70% stuff.

It's at this stage that I'm flummoxed. I can clean it with water 'til there's no longer any white residue on a black piece of cloth. I then go over with a nice clean cloth with IPA and while it's wet it looks lovely and clear. But immediately it becomes cloudy again, leaving powdery trails where I've just applied the IPA. I can just about rub this powder off with a clean cloth but it's a lot of work.

I can only conclude that either the washing isn't working (and I've REALLY tried to clean it) or the IPA is dissolving the plastic and leaving it to dry on the surface. I have tried first using meths and then IPA, and the same happens.

The only way I can get a decent clear finish prior to me clear coating is to use meths on its own, but that will leave a residue being a mineral-based solvent (or at least the guides tell me.)

I've had to wet sand several times as the clear coat I had first was terrible, leaving a crinkly surface rather than a gloss.

Crafty_

13,286 posts

200 months

Thursday 9th June 2016
quotequote all
What happens if you machine polish them, does the clouding go away ?

Summit_Detailing

1,889 posts

193 months

Thursday 9th June 2016
quotequote all
The 800 and 1200 grit will in theory still need further work with lesser grades of paper before polishing, ideally by machine to remove the sanding haze, then IPA to ensure the surface is prepped before applying a quartz or ceramic coating to stop the UV degradation which happened to the original factory finish over time.

cheers

Chris

waxaholic

374 posts

199 months

Thursday 9th June 2016
quotequote all
No mention of machine polishing after sanding?

V8S

Original Poster:

8,582 posts

237 months

Thursday 9th June 2016
quotequote all
The guides I saw said just to leave it at 2000 grit to give the clear coat something to grab on to.

E.g.

https://www.youtube.com/watch?v=UEJbKLZ7RmM

Edited to change 1200 to 2000 grit.

Edited by V8S on Thursday 9th June 18:50

V8S

Original Poster:

8,582 posts

237 months

Thursday 9th June 2016
quotequote all
I don't have a machine polisher.

waxaholic

374 posts

199 months

Thursday 9th June 2016
quotequote all
V8S said:
I don't have a machine polisher.
Ok wiping down with ipa after sanding will leave a dull surface, if your not going to machine polish then use a finer grade of paper before clear coating, TBH i wouldnt renovate headlights in this manner and expect a good result, sanding marks will appear under the clear coat, machine polishing and a coating will yield better results imo.

V8S

Original Poster:

8,582 posts

237 months

Thursday 9th June 2016
quotequote all
waxaholic said:
Ok wiping down with ipa after sanding will leave a dull surface, if your not going to machine polish then use a finer grade of paper before clear coating, TBH i wouldnt renovate headlights in this manner and expect a good result, sanding marks will appear under the clear coat, machine polishing and a coating will yield better results imo.
From all the guides I've read and watched, they seem to get really good results just doing what I've described. It's very frustrating when you try to do as good a job (if anything I've spent longer getting it smoother with 2000 grit) and cross reference guides to make sure they agree, and it still comes out crap. At this rate it'll have cost me more to tidy them up than I'll get selling them!

I've done it again tonight with a new can of Rust-o-leum gloss clear coat and at the moment it's still all bumpy after three coats. Guides seem to suggest that it'll clear after a day. I'm not convinced. It didn't before with the stuff from B&Q. Valspar or something.

If it doesn't work this time, I think I'll just take off the clear coat and use some 3000 followed by some polish and sod the things.

waxaholic

374 posts

199 months

Thursday 9th June 2016
quotequote all
Ok leave the clearcoat to dry, then wetsand them lightly wetsand them with 3000 grit until uniformly dull/flat then polish then back up with a finishing polish, this stage will take a while by hand, it'll make you wish that you invested in a machine/da polisher, good luck.

V8S

Original Poster:

8,582 posts

237 months

Thursday 9th June 2016
quotequote all
I am so so so close to ordering the DAS6 Pro as mentioned in my other post. It usually takes me several months of umming and aahing to decide and buy something. I'm only 2 months in!

I just think, once I've done my two cars and these headlights, I'll have an expensive machine sitting doing nothing for 6 months until the car maybe needs a light polish. Just seems a huge amount of money to tie up at the moment.

Summit_Detailing

1,889 posts

193 months

Friday 10th June 2016
quotequote all
I'm not overly convinced by the results of the youtube video posted above.

I'd happily wager you could achieve better results from the Autoglym headlight restoration kit that attaches to a drill and is available from Halfords.
http://www.halfords.com/motoring/car-cleaning/car-...

It sounds like you've already done the hard work with the aggressive papers, it just needs the final fettling.

Are you local to Portishead? maybe I can help you? - saves buying a DA!

cheers

Chris

V8S

Original Poster:

8,582 posts

237 months

Friday 10th June 2016
quotequote all
Dorset I'm afraid.

Portishead eh? Do you know Paul who used to run JDS?

V8S

Original Poster:

8,582 posts

237 months

Friday 10th June 2016
quotequote all
I have a drill buffing attachment and some Meguiars deep crystal polish which I might try on a slow speed.

Obviously I don't want to wreck the lights because I want to sell them, but equally I don't want to end up spending more on products than they're worth!

The lacquer is still all bumpy and crazed.

V6Alfisti

3,305 posts

227 months

Monday 13th June 2016
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V8S said:
I have a drill buffing attachment and some Meguiars deep crystal polish which I might try on a slow speed.

Obviously I don't want to wreck the lights because I want to sell them, but equally I don't want to end up spending more on products than they're worth!

The lacquer is still all bumpy and crazed.
Plastx works really well on most plastic surfaces, only about £8