Uneven headlight fogginess after sanding

downunderbmer · Yesterday, 11:36 PM

Hi, I have sanded both headlights, starting with 400 grit and working my way up to 3000 grit, using a rotary sander. The results are uneven with fogginess along the lower part of the headlight? What could be the reason for this and could you recommend a possible fix? Many thanks.
Attachment 1

grannyknot · Today, 07:05 AM

I would say your rotary is spinning too fast, it creates heat that can smear the plastic of the lens.
Slow it down and let the grit do the work without heat.

tracer bullet · Today, 08:59 AM

Agreed. It could be uneven pressure as well. Grit and pressure both will change the effect of the sanding, so be sure to be consistent. I always finish any sanding with a particular grit with a light pressure.

Also be sure it's uniformly wet, if the inside or outside is dry with the other wet you could also get uneven results.

I'd also put a 2nd layer of tape down, it can be easy to burn through it accidentally with the edge of the pad while you're focusing on a different area.

Yesterday, 11:36 PM	#1
downunderbmer New Member 11 Rep 28 Posts Drives: 2011 BMW E90 320i LCI N43 Join Date: Jul 2020 Location: Auckland iTrader: (0)	Uneven headlight fogginess after sanding Hi, I have sanded both headlights, starting with 400 grit and working my way up to 3000 grit, using a rotary sander. The results are uneven with fogginess along the lower part of the headlight? What could be the reason for this and could you recommend a possible fix? Many thanks. Attachment 1 Attached Images
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Today, 07:05 AM	#2
grannyknot Captain 1010 Rep 806 Posts Drives: 2008 Z4M coupe Join Date: Oct 2021 Location: toronto iTrader: (0)	I would say your rotary is spinning too fast, it creates heat that can smear the plastic of the lens. Slow it down and let the grit do the work without heat. __________________ 2008 E86 M coupe
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Today, 08:59 AM	#3
tracer bullet Brigadier General 3712 Rep 4,251 Posts Drives: '25 Z4, '15 X3 35i (135i sold) Join Date: May 2011 Location: Saint Paul, MN iTrader: (1)	Agreed. It could be uneven pressure as well. Grit and pressure both will change the effect of the sanding, so be sure to be consistent. I always finish any sanding with a particular grit with a light pressure. Also be sure it's uniformly wet, if the inside or outside is dry with the other wet you could also get uneven results. I'd also put a 2nd layer of tape down, it can be easy to burn through it accidentally with the edge of the pad while you're focusing on a different area.
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