Lens coating removal question

[Dugan]

Hi,
I have an old Wolly Raptar with cloudy Wocote coating on the front element....
I'm considering a make-it-or-break-it effort to make it a semi-useful sorta-focus lens. The coating issue kills any contrast and is very flarey... and not in a good way. :rolleyes:
Can anybody recommend a DIY way to remove the coating?
It's really not a project worth throwing any money at, so any cheap & cheerful helpful hints are appreciated.

[Peter De Smidt]

The AR coating is cloudy? I hadn't heard of that before.

[Dugan]

Yes, it's the coating on the front of the front element. I don't know how it got that way.

[Dan Fromm]

I once had a coated Cooke Aviar with a surface that looked cloudy. After it wouldn't clean up I looked at it with my stereomicroscope. The surface was covered with tiny pits.

[Scyg]

I once got a nice TLR from a friend who said it "didn't take pictures any more". All it took was one good pass with a lens tissue and cleaning fluid. I'm assuming you've tried the obvious.

[Peter De Smidt]

If you Google 'Removing Anti Reflection Coating from Glasses", you'll get a ton of hits.

[Paul Ron]

im sure an acid bath will remove the coatings yet leave the glass n tact.

[Dan Fromm]

im sure an acid bath will remove the coatings yet leave the glass n tact.

Have you tried it?

[LabRat]

I think it was Focal Point that would polish off coatings before re-coating...

Modern coatings are harder, but older "hard" coatings are softer than today...

I was told the finest abrasive is cesium oxide, but don't know where to get it... Jeweler's Rouge is available, and is used to polish glass... But power polishing is not recommended as it builds heat unevenly (and can crack glass), but a glass guy told me lots and lots of hand polishing will work (eventually)...

[Dugan]

Thank you for the suggestions, everybody!
I will try isopropyl alcohol first, then undiluted indicator stop bath, then baking soda, then jeweler's rouge.
Should be an interesting experiment!
Cheers!

[Scyg]

I would not use rouge. Coatings are actually harder than the glass they're on, so if you have any imperfections in the coverage, you'll be digging pits into the exposed glass of the lens while trying to rub off the coating. Voice of experience here.

[Dugan]

Ok, thank you!

[LabRat]

Also, Steichen in the early days used to rub spit on the lens for his pictorial look... :-0

Steve K

[Dugan]

Also, Steichen in the early days used to rub spit on the lens for his pictorial look... :-0

Steve K

His or someone else's? LOL.
I doubt my spit would take Wocote off.

[GoodOldNorm]

Xerapol acrylic scratch polish is very fine and works very well on perspex etc. Toothpaste is also a very fine abrasive.

[Mark Sampson]

An optical engineer posts on this forum as Nodda Duma. Why don't you ask an expert?

[Dugan]

Ok, I tried Isopropyl alcohol, I tried undiluted Stop Bath. I tried toothpaste. No change.
I looked at the front element with an 8x loupe, and the element is badly micro-pitted....toast!
The good news is that I had no expectations going into this experiment...so I can play around with front element spacing, etc. to give it a Fuzzulator with impunity.
Thanks for the ideas & advice, folks!

[LabRat]

I once fixed a chipped condenser in a slide projector by filling the chip with superglue to eliminate the shadow it cast on the edge of the frame once it was filled and slightly polished it down...

I call superglue "liquid plexiglass" as it dries perfectly clear if applied correctly... Sure, it does not have the same refractive index of the glass, but it fills the voids...

The trick is to apply a drop and let it dry at least overnight in a dust - free place, then you will notice it will shrink and thin out, so repeat... Allow a couple of days to dry and repeat, and repeat until it has filled the pits... Then carefully remove excess and polish like plastic...

For your project for fun, this will at least increase the contrast... What do you have to lose???

Steve K

[Dugan]

Hmmm. Sounds like it might be worth a try, I have some of the thin stuff.

[Dugan]

I tried the superglue trick, and it helped a bit! Most of the cloudiness went away! Thanks, LabRat!

[LabRat]

Kool!!! Report back with what kind of images this monster makes...

Steve K

[Dugan]

A quick phone shot of the ground glass.
Some semi- backlit leaves. Had to use hand as a lens shade. Wide open. Pretty flarey...will try again under more controlled circumstances.203732

[John Kasaian]

I was camped out somewhere above Soldier Meadow in the Sierra and my Commercial Ektar needed cleaning.
All I had was Vodka.
That did a number on the coating IIRC,:o

[LabRat]

A quick phone shot of the ground glass.
Some semi- backlit leaves. Had to use hand as a lens shade. Wide open. Pretty flarey...will try again under more controlled circumstances.203732

I think you are on to something there... More!!!

Steve K

[Tim Deming]

I think it was Focal Point that would polish off coatings before re-coating...

Modern coatings are harder, but older "hard" coatings are softer than today...

I was told the finest abrasive is cesium oxide, but don't know where to get it... Jeweler's Rouge is available, and is used to polish glass... But power polishing is not recommended as it builds heat unevenly (and can crack glass), but a glass guy told me lots and lots of hand polishing will work (eventually)...

Cerium oxide, not cesium oxide!

It is readily available, used by those who polish lenses for homebuilt telescopes. I’ve used this successfully to bring life back on lenses with otherwise un-cleanable haze

[LabRat]

Cerium oxide, not cesium oxide!

It is readily available, used by those who polish lenses for homebuilt telescopes. I’ve used this successfully to bring life back on lenses with otherwise un-cleanable haze

Correct!!! Cesium oxide would glow in the dark...

Thanks,

Steve K

[Robert Tilden]

I was told the finest abrasive is cesium oxide, but don't know where to get it... Jeweler's Rouge is available, and is used to polish glass... But power polishing is not recommended as it builds heat unevenly (and can crack glass), but a glass guy told me lots and lots of hand polishing will work (eventually)...

I think he probably said "Cerium Oxide" which is a fairly common fine grit polishing compound. Check amazon here: https://www.amazon.com/Cerium-Glass-Polish-Mineral-Remover/dp/B004QJN98Q

[Dugan]

Hi, thanks for clearing that up.
I have given up trying to clean the lens element, it is micro-pitted, and not worth putting much effort into it.
Using thin superglue, as per LabRat, did knock down some of the haze and brought back some contrast. The lens has a new life as a portrait lens.