[Fenwoodian]

.
Recently I purchased two high quality old manual focus lenses for use on my K1 camera. One was a rare and valuable Pentax lens, and the other a rare Voigtlander lens in KA mount.

Both were advertised as having haze and were being sold for much less than a clean lens without haze was selling for. I thought, no big deal, just take the lens apart, and remove the haze from the lens element (or elements).

Well did I receive a surprise when I took the lenses apart. In each case, the lens had a cemented doublet and the haze was actually inside the cemented elements.

So, tried to take the doublets apart by soaking for days in: alcohol - didn't work; acetone - didn't work. Finally, I soaked the doublet for three days in methylene chloride (dichloromethane). That worked, but in doing so, I was exposed to low levels methylene chloride vapors (had impervious gloves on my hands so no skin absorption).

I used to work for OSHA in the USA. Here's what they say about methylene chloride - "OSHA considers methylene chloride to be a potential occupational carcinogen. Short-term exposures to high concentrations may cause mental confusion, lightheadedness, nausea, vomiting, and headache. Continued exposure may also cause eye and respiratory tract irritation. Exposure to methylene chloride may make symptoms of angina more severe. Skin exposure to liquid methylene chloride may cause irritation or chemical burns."

Knowing about the toxic properties of methylene chloride, I really don't care to ever work with it again.

If you are considering buying a lens at a "too good to be true" price because of internal "haze", you just might want to think twice about buying it. If the haze is inside cemented glass elements you'll either need to have someone else repair this lens for you, or you'll need to work with methylene chloride yourself.

From my research, I couldn't find any other solvent that worked as good on cemented lenses as methylene chloride. Does anyone else out there have any personal experience with a safer and less toxic solvent that is as effective as methylene chloride???
.

[photoptimist]

What about xylene which is used to dissolve canada balsam for microscope slides? It's got a fairly high boiling point (less fumes) although it's still a bit nasty.

You could try something like hexane which seems much less noxious but who knows if it will do the job.

[Auzzie-Phoenix]

Maybe naphta at a real stretch... but it would take several days to a week if it even works.

[Fenwoodian]

Methylene chloride is really the only game in town when it comes to epoxied doublets, unless you want to heat separate them, which runs the risk of breaking them.

If you've ever worked in a lab or have had other hazarodus material training, methylene chloride need not be that risky. Wear gloves, work with it outside, and use tongs, and follow basic safety protocols, and it's not particularly difficult to work with..

Also, FYI, the metabolite of methylene chloride that causes cancer in mice does not occur in human tissues, so it's not clear whether it's even a carcinogen in humans.

---------- Post added 06-05-17 at 05:58 PM ----------



Neither of these will work.

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Thanks so much DCShooter, I greatly value and appreciate your expert advice!

[goatsNdonkey]

Fernwoodian, you didn't say whether you tried out the lenses before taking them apart. It could be the results might not have been as bad as you suspected, if not those a pristine lens could provide.

.
Recently I purchased two high quality old manual focus lenses for use on my K1 camera. One was a rare and valuable Pentax lens, and the other a rare Voigtlander lens in KA mount.

Both were advertised as having haze and were being sold for much less than a clean lens without haze was selling for. I thought, no big deal, just take the lens apart, and remove the haze from the lens element (or elements).

Well did I receive a surprise when I took the lenses apart. In each case, the lens had a cemented doublet and the haze was actually inside the cemented elements.

So, tried to take the doublets apart by soaking for days in: alcohol - didn't work; acetone - didn't work. Finally, I soaked the doublet for three days in methylene chloride (dichloromethane). That worked, but in doing so, I was exposed to low levels methylene chloride vapors (had impervious gloves on my hands so no skin absorption).

I used to work for OSHA in the USA. Here's what they say about methylene chloride - "OSHA considers methylene chloride to be a potential occupational carcinogen. Short-term exposures to high concentrations may cause mental confusion, lightheadedness, nausea, vomiting, and headache. Continued exposure may also cause eye and respiratory tract irritation. Exposure to methylene chloride may make symptoms of angina more severe. Skin exposure to liquid methylene chloride may cause irritation or chemical burns."

Knowing about the toxic properties of methylene chloride, I really don't care to ever work with it again.

If you are considering buying a lens at a "too good to be true" price because of internal "haze", you just might want to think twice about buying it. If the haze is inside cemented glass elements you'll either need to have someone else repair this lens for you, or you'll need to work with methylene chloride yourself.

From my research, I couldn't find any other solvent that worked as good on cemented lenses as methylene chloride. Does anyone else out there have any personal experience with a safer and less toxic solvent that is as effective as methylene chloride???
.

[tabl10s]

.
Recently I purchased two high quality old manual focus lenses for use on my K1 camera. One was a rare and valuable Pentax lens, and the other a rare Voigtlander lens in KA mount.

Both were advertised as having haze and were being sold for much less than a clean lens without haze was selling for. I thought, no big deal, just take the lens apart, and remove the haze from the lens element (or elements).

Well did I receive a surprise when I took the lenses apart. In each case, the lens had a cemented doublet and the haze was actually inside the cemented elements.

So, tried to take the doublets apart by soaking for days in: alcohol - didn't work; acetone - didn't work. Finally, I soaked the doublet for three days in methylene chloride (dichloromethane). That worked, but in doing so, I was exposed to low levels methylene chloride vapors (had impervious gloves on my hands so no skin absorption).

I used to work for OSHA in the USA. Here's what they say about methylene chloride - "OSHA considers methylene chloride to be a potential occupational carcinogen. Short-term exposures to high concentrations may cause mental confusion, lightheadedness, nausea, vomiting, and headache. Continued exposure may also cause eye and respiratory tract irritation. Exposure to methylene chloride may make symptoms of angina more severe. Skin exposure to liquid methylene chloride may cause irritation or chemical burns."

Knowing about the toxic properties of methylene chloride, I really don't care to ever work with it again.

If you are considering buying a lens at a "too good to be true" price because of internal "haze", you just might want to think twice about buying it. If the haze is inside cemented glass elements you'll either need to have someone else repair this lens for you, or you'll need to work with methylene chloride yourself.

From my research, I couldn't find any other solvent that worked as good on cemented lenses as methylene chloride. Does anyone else out there have any personal experience with a safer and less toxic solvent that is as effective as methylene chloride???
.

Is that all? I use to work with Methylethylketone(MEK).When poured into a puddle of water, the dirt at the bottom would spin. Methylisobutlolketone(MIBK)wasn't as bad, The Godzilla of workplace hazards, was Hydrazine which is used in F-16's for in-flight emergencies and in rockets, Oh yeah, I forgot about JP-4 which we poured in the water system. It would bubble if a radio was keyed within so many feet.

[leekil]

So, tried to take the doublets apart by soaking for days in: alcohol - didn't work; acetone - didn't work. Finally, I soaked the doublet for three days in methylene chloride (dichloromethane). That worked, but in doing so, I was exposed to low levels methylene chloride vapors (had impervious gloves on my hands so no skin absorption).

How do you re-cement a doublet accurately?

[Not a Number]

Xylene is some nasty stuff. Used it in labs in college to clean microscope slides and some of the paints for model railroad I used to use were based on Xylene. That crap would melt styrene if you weren't careful. The smell alone is enough to make you sick. I'm glad they took it out of the paints.

Take a peek at the MSDS:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwi...dTFJwhBeCzphpA

[JMMM]

.
Recently I purchased two high quality old manual focus lenses for use on my K1 camera. One was a rare and valuable Pentax lens, and the other a rare Voigtlander lens in KA mount.

Both were advertised as having haze and were being sold for much less than a clean lens without haze was selling for. I thought, no big deal, just take the lens apart, and remove the haze from the lens element (or elements).

Well did I receive a surprise when I took the lenses apart. In each case, the lens had a cemented doublet and the haze was actually inside the cemented elements.

So, tried to take the doublets apart by soaking for days in: alcohol - didn't work; acetone - didn't work. Finally, I soaked the doublet for three days in methylene chloride (dichloromethane). That worked, but in doing so, I was exposed to low levels methylene chloride vapors (had impervious gloves on my hands so no skin absorption).

I used to work for OSHA in the USA. Here's what they say about methylene chloride - "OSHA considers methylene chloride to be a potential occupational carcinogen. Short-term exposures to high concentrations may cause mental confusion, lightheadedness, nausea, vomiting, and headache. Continued exposure may also cause eye and respiratory tract irritation. Exposure to methylene chloride may make symptoms of angina more severe. Skin exposure to liquid methylene chloride may cause irritation or chemical burns."

Knowing about the toxic properties of methylene chloride, I really don't care to ever work with it again.

If you are considering buying a lens at a "too good to be true" price because of internal "haze", you just might want to think twice about buying it. If the haze is inside cemented glass elements you'll either need to have someone else repair this lens for you, or you'll need to work with methylene chloride yourself.

From my research, I couldn't find any other solvent that worked as good on cemented lenses as methylene chloride. Does anyone else out there have any personal experience with a safer and less toxic solvent that is as effective as methylene chloride???
.

ether pro narcosi

---------- Post added 06-06-17 at 12:26 AM ----------

Lens Glue

[steve-rsa]

Xylene is some nasty stuff. Used it in labs in college to clean microscope slides and some of the paints for model railroad I used to use were based on Xylene. That crap would melt styrene if you weren't careful. The smell alone is enough to make you sick. I'm glad they took it out of the paints.

Take a peek at the MSDS:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwi...dTFJwhBeCzphpA

Works really well when added to gasoline for high-boost turbo applications. Don't get it on the paintwork though......

Xylene and Toluene would probably work, but I'm not going to try it myself.

[Digitalis]

Full immersion into Dimethyl sulfoxide (DMSO)@ 120 °C for a few minutes should do the trick. DMSO is commonly used in the semiconductor industry as a solvent for removing epoxy based photoresists. Also DMSO compared to other polar aprotic solvents is quite harmless and easy to handle. You can also try methyl ethyl ketone (MEK) or Dimethylformamide (DMF) - but both of these are rather toxic, flammable, potentially explosive, and have been a causative agent in runaway exotherms. Hexane, Naptha and low-conc Acetic acid are dishwater to Epoxy.

When I was looking up chemical resistance of Epoxy I had a good laugh, elemental fluorine showed up on the list as "incompatible" - no kidding, NOTHING save chlorine can can survive exposure to elemental fluorine unchanged. Though if you're feeling bored, heat those two gasses up and you will end up with something that is categorically worse than the sum of its parts, chlorine trifluoride.

[bdery]

From my research, I couldn't find any other solvent that worked as good on cemented lenses as methylene chloride. Does anyone else out there have any personal experience with a safer and less toxic solvent that is as effective as methylene chloride???

As DCShooter mentioned, what you did was mostly right. You could try methanol also, or go with acids at your own risk.

[GlennG]

If you are considering buying a lens at a "too good to be true" price because of internal "haze", you just might want to think twice about buying it. If the haze is inside cemented glass elements you'll either need to have someone else repair this lens for you, or you'll need to work with methylene chloride yourself.

Fenwoodian, after reading your post and the responses, I'm wondering at what point should old lenses just be discarded? It almost sounds as if lenses are made to be not repairable for some anomalies. Why keep something which is THAT difficult to deal with, if you can even be successful at the repair?

[timw4mail]

What does 'haze' generally end up being?

[Fenwoodian]

Fenwoodian, after reading your post and the responses, I'm wondering at what point should old lenses just be discarded? It almost sounds as if lenses are made to be not repairable for some anomalies. Why keep something which is THAT difficult to deal with, if you can even be successful at the repair?

,
Since buying my K1 cameras, I've tried out well over 100 lenses on them. Also, I have adapted many of these lenses to the K mount. I expect that I've thrown in the trash over 20 lenses in the last couple of years that were damaged while trying to either repair or adapt them. Also, if I do test a cheaper old lens and am not in love with it's performance, I usually throw it away rather than risk selling it and disappointing the buyer.

These days, I've realized that after all of this extensive informal testing, the only lenses that I'm really interested in testing in the future are the Zeiss Milvus 18/2.8 and the Zeiss Milvus 50/1.4. When Pentax comes out with their new full frame glass in the future, I might be interesting in testing them too. Other than that, I'm pretty burnt out with testing (and adapting) old manual focus M42 lenses and old Pentax glass. Given that, I doubt that I'll ever be needing to re-cement glued lens elements again in the future. But, like they say, one should never say "never".