View Full Version : Polishing coating off a lens
Kevin Crisp
3-Oct-2023, 14:53
What would you suggest for removing badly scratched up coating off a lens? I have a big jar of stuff I used to take the scratches off a windshield and was thinking of that. Thanks.
mhayashi
3-Oct-2023, 15:27
I don’t recommend doing it by yourself.
I would suggest you ship lenses to someone professional like Jason Lane….
He has an access to recooating facilities too.
Are you sure the scratching is just on the coating? If it is a real scratch, and it went all the way through the coating -- which isn't thick at all -- it's going to damage the glass. Also, is it bad enough to impact the image? Many times, it isn't, or it's in a location outside of the image area. I guess defining "badly scratched" would help.
Good advice, if the scratch goes through to the glass, then polishing the coating off will just make things worse.
How old is the lens ?
Modern coatings, if done with ion-beam assist, are commonly harder than the glass underneath.
A fun story is about my friend who is a long-time telescope mirror & lens polisher - he had a 4" lens that we re-cemented and then coated with one of our normal avionic AR coats. He then decided to re-figure the rear surface as he thought there was some astigmatism. Using his normal pitch-lap and cerium oxide polishing mix, it took him a week of 2-3 hour efforts to get through the coating. He kept asking me how many layers there were, as he slowly saw each one change colour as he polished through it !
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