View Full Version : Need to Clean Remnants of Cellophane Off Lens

J. P. Mose
21-Jan-2005, 10:49
I obtained a near mint Linhof Technika Press with Zeiss objectives from an estate sale. There is one problem: The 53mm Biogon rear element was in contact with cellophane for several years and remnants of it are on the surface of the lens. It is a very thin film but lens cleaner will not remove it. Before sending it off to Focal Point Lens or similar, is there anything else I could use that is stronger but won't strip the coating?

Also, I notice that one of the rear elements has about a 1mm air bubble in the middle of the lens! I don't how this got through inspection at Zeiss.....so I'm assuming that it must not effect image quality to any measurable degree?

Please advise. Thanks for your help!


David A. Goldfarb
21-Jan-2005, 10:58
I'd e-mail Focal Point or Zeiss and ask what they would use, and they might tell you. My guess would be naphtha, but I wouldn't try it without getting some advice first.

Scott Fleming
21-Jan-2005, 11:54
I would try freezing the lens to see if perhaps the cellophane might curl. Of course one would needs be very careful about bringing the lens back to room temp. Perhaps put the lens in a good plastic sandwich bag before it goes into tthe freezer. Maybe start out in the fridge and slowly take the temp down before putting it in the freezer.

This is just a guess and I don't really know squat about such things.

What about putting a small square (1 inch) of paper towel over the cellophane and putting two or three drops of water on the paper and keep it nearly saturated for several hours (days?) Perhaps it is possible to rehydrate cellophane. Again, just guessing.

Steve Hamley
21-Jan-2005, 11:56
I've used isopropyl alcohol (common rubbing alcohol) before with stubborn haze and good results.

Air bubbles (air bells) are not defects and are common in older optical glasses.

http://www.glennview.com/lens.htm (http://www.glennview.com/lens.htm)


Ole Tjugen
21-Jan-2005, 12:44
At one time the air bubbles were taken as circumstantial eveidence that the lens was made from "Gutes Jenaer Glas" - Good Glass from Jena. For "Glass from Jena", read "Schott".

The special glasses which were so important to the top-end lenses were very difficult to melt, and frequently had bubbles. Too many bubbles, and the glass was rejected. So I would think that Zeiss would have approved your lens.

You have forgotten to mention the vintage of the lens, BTW. I believe the discard limit changed quite a lot through the years...

Arne Croell
21-Jan-2005, 13:08
If the alcohol doesn't work, a last resort might be acetone, which is a solvent for many plastics. I have used it once without problems on an Apo-Germinar from a print shop that had some transparent gluelike material on the lens. It should be ok with the coating, but you have to be careful not to touch any of the metal mounting since it will immediately dissolve any paints, lacquers and dyes in anodized aluminum. Use it sparingly on a piece of lens tissue (Kimwipes are good) and then apply it, several times. I am sure you know this, but never put it directly on the lens (that goes for all lens cleaning solutions). Note that acetone, especially the technical grade available in hardware stores, leaves a residue which can be cleaned with alcohol (after removing the other stuff).

george jiri loun
21-Jan-2005, 14:21
Try a dropp of olive oil, leave it for a moment. Clean then with cloth and with a lens cleaner.

John Kasaian
21-Jan-2005, 18:37
Vodka?? If it dosen't make the cellophane go away, you can drink it!

Paul Fitzgerald
21-Jan-2005, 19:56
Hi there,

The safest way to remove tape residue is 100% Pure Carnauba paste wax and a soft paper towel. It will not damage the glass or coating and will remove the goo from glass, chrome, leather or wood. Take your time and let the wax soften the glue. It will clean up very well and you can remove the wax with lens cleaner if you wish.

Just a thought.

22-Jan-2005, 01:26
"The safest way to remove tape residue is 100% Pure Carnauba paste wax "

Just a tiny quibble... "Pure Carnauba" is brittle & hard like hard candy. To turn it into paste it is disolved in something, like turpentine. If you don't know what that solvent is, be careful.

Robert A. Zeichner
22-Jan-2005, 06:44
I belive Arne is on the right track. Spectrographic grade Acetone is what is often used to clean lens elements during overhaul (I used to do this for a living). Just be careful as he suggested. Acetone will remove paint and worse yet, dissolve the cement that holds elements together in groups. Just a little at a time applied gently with a Q-tip should do the trick. The stuff you get at the paint store will be sastifactory for what you are doing. Also, extinguish flames, cigars, etc. and don't breath this stuff a whole lot.

Paul Fitzgerald
22-Jan-2005, 11:50
Hi there,

"100% Pure Canrauba wax"

Personally I use "Mother's California Gold - natural formula" pure carnauba paste wax with NO cleaners. I'm sure "Meguiar's" would work as well. "Blue Coral" is too hard to remove and off- brands have too much solvent in them. I have never tried "Butcher's wax". I believe the solvent in most waxes is 'stoddard solvent', it's only listed as petroleum distillate.

Paste wax will remove tape residue from anything and damage nothing including antique shellac, varnish or lacquer finishes, leather, woodwork or black enamel on lenses. Make sure the can states "NO CLEANERS", cleaner waxes have abrasives in them. DO NOT use liquid wax. All of the other solvents listed here are flammable or explosive, messy and smell like death AND they can all do serious damage to camera parts.

Sorry, but I just LOVE those stickers too many people like to put on cameras and lenses.

Good luck with it.

J. P. Mose
22-Jan-2005, 12:01
Thanks for all the replys!

Chris Gittins
23-Jan-2005, 06:04
"The [acetone] you get at the paint store will be sastifactory for what you are doing. "

I've never been real happy with straight, run-of-the-mill acetone for optics cleaning. The issue is impurities (heavier hydrocarbons) which don't evaporate away and end up leaving a visible film on the lens. (Admittedly, this was more an issue when I was working with UV lasers and not so much now with my lenses, but my laser experience made me a stickler for getting optical surfaces very clean. If I didn't get the beam turning mirrors and prisms clean, the UV would effectively burn on whatever I hadn't gotten off and degrade the optic's characteristics accordingly.) Two thoughts for your situation:

1) Use "spectroscopic grade" acetone. It's considerably more expensive and harder to find - try Fisher Scientific - but leaves much less residue than what you'll get from the hardware store. As noted above, be careful not to get it on paint, lens cement, or anything else you wouldn't want dissolved and coated onto your lens.

2) Use hardware store-grade acetone for heavy cleaning and then a second solvent, such as methanol or isopropanl, to clean up after it. I've had pretty good results using this approach. You still need to worry a little about the purity of the methanol/isopropanol, but it's probably more convenient to use two reasonably clean solvents than to find one super-clean one. Also, whatever impurities there are in the methanol/isopropanol will tend to be soluble in off-the-shelf lens cleaning solutions. Worst case make it a three step process: acetone then methanol then lens cleaning solution.

Good luck,

Arne Croell
23-Jan-2005, 09:07
I agree with Chris completely that a better grade acetone would be preferable. I assumed, however, that J.P. might have trouble getting it. Where I work, we use semiconductor grade acetone and Methanol a lot, but nowadays I have to sign off when we buy it that it will only be used for research purposes (here in Germany) - something to do with the use of acetone in some illegal drug production process.
So the industrial grade acetone solution is not the best possibility but works, with a subsequent cleaning with alcohol or lens cleaning solution as indicated above.

Chris Gittins
23-Jan-2005, 11:03
>nowadays I have to sign off when we buy it that it will only be used for research purposes (here in Germany) - something to do with the use of acetone in some illegal drug production process.

Good point. I suspect we have the same procurement issues here in the US that Arne does in Germany. Using spectroscopic grade solvents is probably a moot point unless you happen to have access to them through work, etc. When I need to clean a lens I just bring it in to my lab and use a few drops from the bottles I have sitting on the shelf. I've never tried to buy any for personal use. Along those lines, I just checked the Fisher website. Even if procurement wasn't an issue, their good grades of methanol are $50-80 per liter. Spectroscopic grade acetone was more than $60 per liter. Ouch.


Jon Shiu
23-Jan-2005, 15:07
Hi, since there are science people here I thought I'd ask: would WD40 work and why or why not? (It works good to get sticker gunk off of CD cases).

Chris Gittins
23-Jan-2005, 17:08
I went looking for a can of WD40 in my basement but couldn't find one - I'll fix that tomorrow - so, since I can't read the ingredient label, what follows is my semi-educated guess. I'd expect WD40 would do a reasonable job of dissolving gummy substances, but since its an oil itself it'll be miserable to clean off. It's main components are non-volatile so you'll need something like acetone or lots of soap and water to wash them off. It's also a penetrating oil, so it'll take forever to get it out of any pores it gets into. Roughly speaking, WD40 is made up of the impurities in industrial grade acetone that you're trying to avoid by buying spectroscopic grade acetone. (Again, that's my semi-educated guess. Someone may step up and correct me.) It may get the gunk off the lens but it'll likely cause bigger problems in the process. But I love it for freeing up rusted bolts!


Robert A. Zeichner
23-Jan-2005, 18:13
WD-40? I wouldn't. This stuff contains silicone and is murder to get rid of once you get it on the glass. Stick with acetone, methanol or butylcelusolve, if you can get it (miscible ether that dissolves in water). A 1:7 dilution will render it safe from a flamability standpoint. But the suggestion that ordinary acetone followed with methanol will work just fine.

J. P. Mose
26-Jan-2005, 13:15
Thanks for all of this information. I did try acetone. It cleaned off the residue and I was able to clean away the acetone residue as well. Unfortunately, it appears that the coating (or lens surface) is dulled or marred to a certain extent. I am going to send off the lens to Focal Point lens and have Ken polish and/or recoat the surface. This is a real clean Technika Press 23 set and I got it for a reasonable price. Hence I'll bite the bullet and pay the $300.