Managed to burn headlight plastic a bit - but I didn't see that coming

[jovan90jovanovic]

Hi guys, this is my first post here so I'd like to thank everyone for providing tons of valuable information. I like my machines a lot, we are friends, and I like to have them in best possible shape at all times. Question I have is about headlights on 2008 BWM X6, about polishing headlights actually, these headlights come later. It all started because previous owner had them varnished (lacquered them for protection), and that started peeling off. Of course, I went to expert asking him to remove them completely, sand that protection of, and polish headlights.

This is what I received:

I'm sure everyone can see what I want to fix. I didn't wanted to go back to that 'expert' - I just don't have nerve for arguing, I'll make it right myself.

So, I decided to test what I know on some older (also plastic) headlights. Being in Europe, I can easily get SONAX products - and from what I've seen here, they should be very good. I haven't found any special 'headlights restoration' kit or anything. Instead,
I've got 2 standard polishing products:
a) Robot Check
b) Sonax Perfect Finish, best car polish

Regarding tools with acceptable rpm, I've got 2 tools:
1) BOSCH accu drill with 2 speeds. 600rpm and 1500rpm. Light tool, does not apply too much pressure naturally.
2) BOSCH power drill with max speed of 3000rpm but I limited it to around 2000rpm. Heavy tool, easier to apply pressure.

As mentioned, I was testing everything on some older headlights - didn't jump straight onto the BMW.
a1) Using EX 03-06, with 2 passes on 600rpm and like 6 passes on 1500rpm makes the headlights very shiny, but isn't able to remove any deeper scratches, it just removes "cloudiness" and makes them shiny. I figured that won't work on BMW deep scratches.
b2) Using Perfect finish, with 2 passes slowly and then about 6 passes on 2000rpm, I managed to burn the plastic in few places. To be honest also, I didn't see much of an improvement, as if 03-06 removed more scratches than this "b2" combo

What I would like to learn here is, why did burns happen? I didn't take a picture of burns but I can, smudged plastic on few places that probably can be 'saved' with a lot of sanding. What is the main issue for that, is it the speed? is it the product? is it weight of the machine? Because, I really wasn't expecting burns, I used light SONAX foam pad (green), I wasn't applying too much of an additional pressure, I was moving, I really didn't keep the drill in one place letting it burn it. I can see that guys are recommending even higher speeds with buffing tools, like 3000rpm - so I'm also not sure that the speed was the problem.
Is it possible that the product, Perfect Finish, simply does not work well on the plastic and that it shouldn't be used for plastic?

[tmdals0213]

If im assuming correctly, you are using a power drill and not a dual action polisher, correct?

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How much lubrication did you have on the pad? A lot polish or 3-4 dots? Might be caused by dry buffing..?
Just generally speaking, seems like the polisher was over the burned spots more so than the other areas.. but i do see you said you were moving it around..

They do look like hairline cracks as well from just heat by general use. (Sanding required)

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Ive also been told perfect finish is geared towards rotary+wool combo use

[Thomkirby]

What pad were you using?
Also SONAX does make a headlight restoration kit, or we can buy it in the USA vendors, assume you can too!

Your polish is good choice but only as a final step to remove light sanding marks, 3000-grit or higher.

It is possible that some of the lights have internal heat damage or UV-caused cracking or cloudiness inside the lamps and cannot be removed.

[tmdals0213]

Yeap yeap exactly what thom said

[tmdals0213]

What pad were you using?
Also SONAX does make a headlight restoration kit, or we can buy it in the USA vendors, assume you can too!

Your polish is good choice but only as a final step to remove light sanding marks, 3000-grit or higher.

It is possible that some of the lights have internal heat damage or UV-caused cracking or cloudiness inside the lamps and cannot be removed.

I asked that question myself and i found he was using a sonax green pad, might be a med firm pad? Not sure - never used sonax pads before

[jovan90jovanovic]

Hi guys, thanks for a lot of nice responses and sorry for the delay - seems like I have to switch email notifications on manually.

If im assuming correctly, you are using a power drill and not a dual action polisher, correct?

- Yes, power drill, some standard BOSCH power drill with max 3000rpm but I have limited it to something about 2000rpm. Has speed adjustment.

How much lubrication did you have on the pad? A lot polish or 3-4 dots? Might be caused by dry buffing..?
Just generally speaking, seems like the polisher was over the burned spots more so than the other areas.. but i do see you said you were moving it around..

- Exactly 6 dots distributed around the headlight with low speed, and then switched to higher speed for polishing.

Ive also been told perfect finish is geared towards rotary+wool combo use

- What DID happen tho, and you got me thinking about it, compound (Perfect Finish) did dry out, and it dried out very quickly. By 'dried out' I mean it started turning to 'white dust' and it didn't seem like it was lubricating any more, it was simply falling off when I passed through that area.
Did I dried it out (and by doing that caused high temperature that burned plastic) by applying a lot of pressure maybe or by staying on a headlight for too long?
Is compound supposed to dry out? Maybe I just stayed on a headlight for too long. How long would you generally stay on 1 headlight?

Regarding pads, this one was used: SONAX Green Medium Polishing Pad 6.25 in. (160 mm) - recommended to use with their Perfect Finish