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Fungus!

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#1 jragsdale

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Posted 16 May 2022 - 01:00 AM

I've got a Unitron 60/700 guidescope lens that has a pretty nasty case of of the fungus. I've read that hydrogen peroxide bath is the method of choice. What strength and how long?

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#2 happylimpet

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Posted 16 May 2022 - 05:05 AM

I wanted to press like, because its such a cool photo of the fungus!


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#3 jragsdale

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Posted 16 May 2022 - 08:35 AM

I wanted to press like, because its such a cool photo of the fungus!

I was trying to get a photo of the fungus with a small USB magnifying camera (the kind you use for inspecting inside your ear) but couldn't get anything good. Then I just held my cell phone about 12 inches straight above the lens and had the LED light from the camera shining down and when I lined up the 2 reflections of the LED in the camera, it created this really cool interference pattern where it would white over the whole lens at just the right spot and showed all the detail inside the lens. It came out kinda bluish and red, so I converted to monochrome and bumped up the contrast a little. I agree, it turned out really cool and really shows all the detail well in the fungus!


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#4 ngc7319_20

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Posted 16 May 2022 - 09:02 AM

I would probably use 91% Isopropyl Alcohol which is readily available at drugstores, etc.  I haven't tried Hydrogen Peroxide.  Either way, anything will be better than its current state.



#5 ccwemyss

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Posted 16 May 2022 - 09:18 AM

I've had fungus that doesn't respond to alcohol (sometimes it does). When desperate, I've used bathroom cleaner that includes dilute chlorine bleach in it (e.g., Scrubbing Bubbles with Bleach), followed by a minute of tap water rinse, then distilled water rinse. In some cases, I've followed that with isopropyl, if there are remaining sleeks. If the fungus has eaten the coatings, there may still be marks visible with reflected light, but usually there is nothing visible when looking through. If there is, then the fungus has etched the glass itself. 

 

Chip W. 


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#6 Piggyback

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Posted 16 May 2022 - 02:25 PM

TM von 1989 Ankauf_04red.jpg
TM von 1989 Restaurierung_03red.jpg
 
Dramatic photograph, yet no reson for despair. Yours looks manageable. I remember the shock when I got this infected Telementor lens. Careful wiping of the lens with Baader lens fluid helped to get rid of the fungus. Prolonged UV exposure and scrubbing of the inner tube is also recommended. Looking forward to see your after pictures. I am confident you´ll get there.waytogo.gif

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#7 jragsdale

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Posted 16 May 2022 - 03:35 PM

12 hour HP soak followed by a rinse, then 91% isopropyl alcohol wipe with PEC pads. If you really hunt around in the reflections you can see the outlines of the original fungus, but 99% of the time from 12" in front of my face it looks perfect. I'll call this a success!

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#8 Brianm14

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Posted 16 May 2022 - 06:42 PM

Good job!

 

While hydrogen peroxide may effectively attack vegetative cells, fungal spores are very resistant to most chemicals.  Remove both cells and spores by carefully and repeatedly cleaning with lens cleaning fluid (or two drops of blue Dawn detergent in three or four ounces water) and quality lens tissue or PEC pad.  “Rinse” with plain water on a lens tissue.  This primarily physical method is more likely to be effective than chemical treatments.

 

Straight hydrogen peroxide from the drug store is available in 3% (ten volume) medicinal strength or the 6% (twenty volume) strength used to bleach hair.  Dilutions to 1.5% or less are common in peroxide-based disinfectants.   Hydrogen peroxide is most likely to be effective on a pre-cleaned surface.  But outside of using hydrogen peroxide on obligate anaerobic bacteria (which are intolerant of oxygen) I am not terribly impressed by it.  You were heading in the right direction by allowing a long exposure time.

 

Chemically, I’d go with careful cleaning first and then several minutes exposure to 70% (or up to 80%) isopropyl alcohol.  The 91% concentration is not a better disinfectant; indeed, the opposite may be true.  The higher concentration also evaporates more quickly.  

 

Bleach would be a pretty harsh treatment and destructively alkaline, likely attacking glass and coatings; however, I would worry as much or more about the strong cleaning agents present in a bathroom cleaner.

 

These fungal cells and spores of various species are found everywhere and really cannot be eliminated.  So prevention through storage under reduced relative humidity is the key to this problem.  As you know, successfully treating an established infestation isn’t easy.
 

 But it is wrong to argue with success!  So congratulations!  My hat is off to you for being determined.


Edited by Brianm14, 16 May 2022 - 06:43 PM.

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#9 deSitter

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Posted 16 May 2022 - 09:44 PM

Does this fungus have a preference for crown or flint glass?

 

I've never come across fungus so far in my "career". I check for it about twice a year on my various classics. It is good to know it's not fatal.

 

-drl



#10 jkmccarthy

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Posted 16 May 2022 - 09:48 PM

This reply is too late to help the OP, but might help future CN users who find this thread in their searching.

 

 

Here are links to three previous posts with recipes for successful removal of fungus from lenses using a combination of hydrogen peroxide and ammonia[*]:

 

https://www.cloudyni.../#entry10073226

 

https://www.cloudyni.../#entry10863387

 

https://www.cloudyni.../#entry10935890

 

EDIT:

[*] *** But see also post #15 below by Brianm14 regarding use of ammonia -- https://www.cloudyni.../#entry11902325


Edited by jkmccarthy, 17 May 2022 - 08:32 PM.

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#11 clamchip

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Posted 17 May 2022 - 10:50 AM

When and if this link is back its an excellent article on fungus:

http://www.europa.com/?f

I also would like to mention fungus likes binoculars too, and the above article covers binoculars as well as

anything optical.

I personally had fungus in a WW2 Japanese binocular. Absolutely fantastic glass in this binocular. And it's

really cool because the aluminum parts are sandcast, a beautiful example of the art of sandcasting.

A complete tear down is required and is quite a bit of work. The infected binocular is un-coated and one of

my favorites.

The only way I can see doing the job properly is disassemble and clean every part individually and flush out

the body too.

I start by cleaning the optics as I normally would with 1:10 iso alcohol-water, and a drop of Dawn Original only

I add a splash of hydrogen peroxide. Use the left over solution to flush or sponge the mechanical parts like

cells, barrels, etc.

 

Robert


Edited by clamchip, 17 May 2022 - 11:02 AM.

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#12 John Higbee

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Posted 17 May 2022 - 10:58 AM

I'm about to start "de-fungusing" an older Unitron Model 150 objective lens.  Thanks for this thread...very timely for me!

 

John

 

objective.jpg


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#13 Brianm14

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Posted 17 May 2022 - 01:28 PM

Does this fungus have a preference for crown or flint glass?

 

I've never come across fungus so far in my "career". I check for it about twice a year on my various classics. It is good to know it's not fatal.

 

-drl

There are a number of species of fungus (from several larger taxonomic groups) which attack glass.  Any dust or dirt present will be exploited as food as well.  As far as I know, there no preference has been detected for crown or flint glass, but this aspect may not have been studied per se.  A good question.

 

Based on what happens with photographic and microscope lenses, it is fair to say that fungal infestations or infections most certainly tend to be fatal.  Once started, the glass surface and antireflective coating(s) will assuredly suffer damage.  Fungi has proven to be end of too many fine optics!  Prevention through proper is the only sure route to preclude damage to or loss of fine lenses.

 

Anti-fungal coatings have been developed for optical glass surfaces and are especially valuable in tropical or semi-tropical heat and humidity. 


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#14 Brianm14

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Posted 17 May 2022 - 01:29 PM

“The only way I can see doing the job properly is disassemble and clean every part individually and flush out
the body too.
I start by cleaning the optics as I normally would with 1:10 iso alcohol-water, and a drop of Dawn Original only
I add a splash of hydrogen peroxide. Use the left over solution to flush or sponge the mechanical parts like cells, barrels, etc.”

 

Good points.  All glass surfaces in optical instruments are on the “menu” and candidates for attack. The way in which most binoculars are used and carelessly stored would seem to favor fungal attack!

 

Yes -All instrument surfaces must be carefully cleaned to remove fungus.

 

Your cleaning solution sounds safe.  It is the surfactant (the drop of Dawn) which does the real work.  I use a few drops of any blue Dawn in three or four ounces water or something like Zeiss lens cleaner, or more and more often, Sparkle glass cleaner diluted 1:1 with distilled water.  The latter formulation is favored as a lens cleaner by such savvy places such as the Duke University Imaging Center; glycol-based, it is a surfactant package and likely has some disinfectant properties.  

 

Sparkle 1:1 is my choice as a lens cleaner in biology teaching labs.
 

Sparkle is available at better hardware stores (e.g. ACE) or most cheaply via Amazon (a gallon is under $20USD, Prime shipped).  Diluted, that’s a cheap lens cleaner!  Good kitchen cleaner, too, use straight.

 

Good luck to all dealing with fungus!

 

CS,

Brian


Edited by Brianm14, 17 May 2022 - 01:55 PM.

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#15 Brianm14

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Posted 17 May 2022 - 02:19 PM

This reply is too late to help the OP, but might help future CN users who find this thread in their searching.

 

 

Here are links to three previous posts with recipes for successful removal of fungus from lenses using a combination of hydrogen peroxide and ammonia:

 

https://www.cloudyni.../#entry10073226

 

https://www.cloudyni.../#entry10863387

 

https://www.cloudyni.../#entry10935890

Respectfully, I must disagree and cannot support the use of ammonia.

 

 

Ammonia is of questionable safety when used on optical glass.  It will certainly help remove fungi, but is a base (high pH, an alkali) and as such will chemically attack, and given time, even etch glass.  Ammonia will also damage optical coatings, perhaps even more quickly than it damages glass.  I’ve never seen it's use sanctioned or recommended by lens makers.

 

 

More modern lenses can be safely cleaned with 70 - 80% isopropyl alcohol, which both cleans and disinfects.  Alcohol is likely unsafe to use on older or vintage lenses due to the type of lens cement used.  But cleaning and removing vegetative cells and fungal spores are the big points in this intervention anyway, so mild surfactants (e.g. detergents, glycol solutions) are what’re important.  Plain Windex, without ammonia, can be used but I prefer Zeiss lens cleaner or Sparkle (diluted 1:1 with water) as a commercial product. 

 

CS,

Brian


Edited by Brianm14, 17 May 2022 - 02:27 PM.

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#16 Feldmeister

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Posted 17 May 2022 - 08:01 PM

I'm new to astronomy & telescope repair, but I've messed with camera repair since I was in high school in the 90s. Back then, I recall reading in several places to use basic Pond's Cold Cream to remove fungus. I've used it a couple times with good effect, most recently on a Unitron 75mm I picked up a couple weeks ago. At the right angle, you can still see coating damage where the fungus was, but it's clearly no longer present. The cold cream removed the fungus with no rubbing, but I did have to do a few applications - I just smeared it on thickly, let it sit for an hour or two, then rinsed it off. Naturally, then I had to get the cold cream residue off, but that was pretty easy with water-Windex-water rinses. I did final rinses in distilled water and in methanol before reassembly. 

 

Are there any reasons not to use cold cream?


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#17 Brianm14

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Posted 17 May 2022 - 10:07 PM

I'm new to astronomy & telescope repair, but I've messed with camera repair since I was in high school in the 90s. Back then, I recall reading in several places to use basic Pond's Cold Cream to remove fungus. I've used it a couple times with good effect, most recently on a Unitron 75mm I picked up a couple weeks ago. At the right angle, you can still see coating damage where the fungus was, but it's clearly no longer present. The cold cream removed the fungus with no rubbing, but I did have to do a few applications - I just smeared it on thickly, let it sit for an hour or two, then rinsed it off. Naturally, then I had to get the cold cream residue off, but that was pretty easy with water-Windex-water rinses. I did final rinses in distilled water and in methanol before reassembly. 

 

Are there any reasons not to use cold cream?

This is an interesting approach, novel to say the least!  I am just not sure it is superior overall to a far less messy treatment with lens cleaning solution and “scrubbing” with lens tissue. With the more standard treatment, one can also remove all traces of fungus and finish up with alcohol.  My question turns yours on its head, asking, is there any reason to use cold cream?

 

Ordinarily, we strive to keep oily or greasy substances far away from optical surfaces.  They are hard to completely clean off.

 

Cold cream is an emulsion.  These can have useful properties.  But cold cream also contains number of ingredients and some may come into play if there are indeed any unique cleaning properties present.  (Of course, some of these ingredients could be harmful to glass or antireflective coatings.)

 

For any given process, it is not uncommon to find offbeat alternative methods.  What is uncommon is find them superior to the standard.

 

I am not questioning what you have reported.  You obtained effective removal of the fungus.  We should treasure an open mind.  But direct comparisons would have to be made to demonstrate that the cold cream method is better.  As it is, it sounds “at most, about as effective.”  At most.  This why a trial comparison is needed.

As it stands, it is not going appear as a even an alternative recommended method on any legitimate optics website.

 

Brian


Edited by Brianm14, 17 May 2022 - 11:00 PM.

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#18 Feldmeister

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Posted 17 May 2022 - 11:06 PM

This is an interesting approach, novel to say the least.  I am just not sure it is superior overall to a far less messy treatment with lens cleaning solution and “scrubbing” with lens tissue. With this standard treatment, one can remove all traces of fungus and finish up with alcohol.  My question, is there any reason to use cold cream?

 

Ordinarily, we strive to keep oily or greasy substances away from optical surfaces.  They are hard to completely clean off.

 

Cold cream is an emulsion.  If an emulsion cleans well, mayonnaise and a number of other emulsions would serve in place of cold cream.  

 

I am not questioning what you have reported.  We should treasure an open mind.  But direct comparisons would have to be made to demonstrate that the cold cream method is better.  As it is, it sounds “about as effective.”  At most.  

As it stands, it is not going appear as a even an alternative recommended method on any legitimate optics website.

 

Brian

Brian, 

 

Thank you for the insight! I definitely was not trying to tout cold cream as a superior fungus treatment to any of the others mentioned, nor to claim to be an expert - I was just saying that it seems to work well the times I've used it, and I was interested to know if anyone might know of some negative effect that I was unaware of (like the possibility of causing further coating degradation). You are correct that cold cream is somewhat oily, but I had a plan for that, and feel I managed to clear it fairly well. The final few baths (distilled water+IPA - distilled water - methanol) were done with the elements suspended in beakers of solution via custom fixtures and continuous agitation applied via spin bars & magnetic stirring hot plate. 

 

I do have a question about your statement saying any number of emulsions could serve in place of cold cream. In this case, without looking at the ingredients, if cold cream is an emulsification of a polar solution & a non-polar solution, is it possible there's some chemical component in either the polar or non-polar part that is capable of removing the fungus? I just question the parallel to mayonnaise being a possible alternative since its an emulsion instead of the saying mayonnaise is a possible alternative because it contains a certain chemical component. I'm definitely not trying to sound rude - it's just been a while since I studied chemistry, and I know I've forgotten a lot!

 

Thanks!

Ron


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#19 jkmccarthy

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Posted 18 May 2022 - 03:28 AM

Respectfully, I must disagree and cannot support the use of ammonia.

 

Ammonia is of questionable safety when used on optical glass.  It will certainly help remove fungi, but is a base (high pH, an alkali) and as such will chemically attack, and given time, even etch glass.  Ammonia will also damage optical coatings, perhaps even more quickly than it damages glass.  I’ve never seen it's use sanctioned or recommended by lens makers.

[...]


CS,

Brian

Thanks, Brian, for your cautionary note, which piqued my curiosity -- so I've been digging further into this all evening.  Agreeing with the points you raised regarding ammonia, I was particularly curious to understand better whether the same concerns apply to a 50/50 mixture of [household] hydrogen peroxide and [household] ammonia.   Hydrogen peroxide obtained at a pharmacy can have a concentration ranging from 3% up to 20% (and will be acidic ... for 10% concentration, I gather the actual pH is near 3 after acidic stabilizers are taken into account).  Meanwhile the concentration of household Ammonia typically is between 5% and 10% (and is a base, as you correctly point out ... at these concentrations its pH is about 11.5).

 

Hence the 50/50 ammonia peroxide mix (APM) will be a weak base ... and presumably safer to use on optical surfaces than straight household ammonia alone.

 

As far as I've been able to tell, the 50/50 APM solution for chemical cleaning was originally developed by Werner Kern at RCA in the mid-1960s, for application to the cleaning of polished silicon wafers prior to semiconductor fabrication, where APM was known as RCA's "Standard Clean" step 1, or SC-1 (https://en.wikipedia..._particle_clean), which also became known as RCA-1 after it was more widely adopted across the industry (e.g., see also https://www.inrf.uci...licon-rca-1.pdf ...).   RCA-1 specifies 1-part each of industrial strength ammonia and peroxide (27% and 30%, respectively) diluted into 5 parts de-ionized water, effectively reducing the concentrations to 11% or 12% (i.e., comparable to the concentrations of household products).   A notable feature (and something I would never recommend for our lens optics !) is that the RCA-1 recipe calls for heating the solution to about 70C temperature prior to soaking the silicon wafers in the hot APM solution for 10 to 15min ---  my guess is that the elevated temperature is to encourage the reaction with the Si surface that leads to the formation of a thin silicon dioxide layer on the surface (which is itself removed from the polished silicon wafers in a subsequent step of Kern's RCA Standard Clean process...).

 

FWIW, I also happened to run across this blog post illustrating the use of a 50/50 APM solution for cleaning fungus from camera lens optical surfaces:

 

https://petapixel.co...ve-fungus-lens/

 

... which closely parallels two of the three CN threads that I linked to previously in post #10 above.  (NOTE the *EXCEPTION* is the third link I selected, where the author alternates between soaks in soapy water, then ammonia, then soapy water, then hydrogen peroxide, and then soapy water, with rinsing the optic after each soak.   In light of the pH concerns Brian has raised, justifiably, the recipe detailed in the third link I included in post #10 above seems likely to pose an elevated risk of etching the coating and/or glass surfaces, compared to the other recipes based on the 50/50 APM solution.  True ?).

 

Based on my on-line digging, I presently cannot say with certainty that the 50/50 APM (ammonia peroxide mix) solution won't result in any micro-etching.  Indeed by the early 1990s, advances in photolithography equipment and semiconductor design + fabrication techniques were pushing towards smaller and smaller integrated circuit feature sizes to such an extent that stricter demands on wafer flatness and surface polish were required, causing the degree of micro-etching [i.e., the increase in surface roughness] incurred during RCA SC-1 and SC-2 cleaning to come under scrutiny.  Researchers soon found that the fluid temperature played a greater role with respect to surface roughness than did the concentration of the reagents, leading to the discovery that a 2x improvement in surface roughness (from 8 Angstroms r.m.s. surface roughness after cleaning, down to 4 Angstroms r.m.s. instead) when the temperature was reduced from 70C to under 50C.

 

But keep in mind a polished Si wafer is not the same thing as a polished optical glass (crown or flint or fluorite etc.) surface, nor is it the same as thin-film anti-reflection coated surface (Si may be a more reactive surface?) ... and everyone here who has used 50/50 APM to remove fungus has likely soaked their lens surfaces in room temperature (~ 20C) liquid, not even 50C.  And on a lens surface, 4 Angstroms r.m.s. surface roughness would fall nearly into the "super-polished" category of exceptional smoothness (which often describes <2 Angstroms r.m.s. surface roughness), versus the roughly 10 Angstroms r.m.s. surface roughness that typically results from commercial optical polishing methods.

 

So despite having yet to find "scientific proof" that a 10 to 30min soak in 50/50 APM solution (using "household" 5% to 10% concentrations of ammonia and peroxide mixed 1:1) won't harm our optical surfaces and/or coatings via micro-etching, I believe that enough amateur-owned astronomical objective lenses (and photographic camera lenses) have undergone this treatment to remove fungus -- without reports of negative consequences afterwards -- for me personally to conclude that the risk of adopting this recipe is low.  Others certainly may assess the risk differently.  *** And to the extent that alternative methods exist (e.g., as Brian outlines in the bottom half of post #14 above) that are more certain to be pH-neutral, then "why accept any risk of micro-etching at all?" is certainly a valid question to ask / consider. ***

 

Food for thought, and thanks again Brian !

 

       -- Jim

 

 
 



#20 jkmccarthy

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Posted 18 May 2022 - 05:24 AM

P.S.  Here are links to large-size "before" (in normal room light) and "after" (under much brighter incident light) photos of the objective lens of my vintage Vixen 80mm f/15 refractor (my first Zen-Market purchase, sight-unseen as far as the objective lens was concerned -- not a recommended practice : - ), cleaned of fungus using the 50/50 APM recipe for fungus removal that I adopted after learning of it in CN Classic Telescopes forum posts.

 

I had no way to assess surface roughness / scatter "before" undertaking the cleaning operations, but the "after" photo (as well as visual inspection) attests to very low / negligible surface scatter post-cleaning ... suggesting I got lucky the fungus hadn't yet progressed to the point of eating into the lens' coatings.


BEFORE large photo link (suggest opening link in a new tab):

https://www.cloudyni...7082_349451.jpg

 

AFTER large photo link (ditto):

https://www.cloudyni...7082_124844.jpg


Details can be found in this July 2021 blog post in the Vintage Telescope Finds thread:

https://www.cloudyni...6#entry11257860

 

I've seen the climate in many parts of Japan described as "sauna-like" ... hence many of us who have purchased used (vintage) refracting telescopes via Zen-Market from sellers in Japan have at least some first-hand experience having had to clean fungus from lenses.   But never-too-old --- indeed happy --- to learn more about the associated do's and don'ts, and the safest and most effective recommended best practice(s) for this.

 

Clear Skies,

 

       -- Jim

 

 


Edited by jkmccarthy, 18 May 2022 - 05:27 AM.


#21 Brianm14

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Posted 18 May 2022 - 02:27 PM

Thanks, Jim.  Great posts!  Your posts are both thoughtful and thought-provoking.  I will need to re-read and think again on what you’ve so usefully posted.  Here are my more immediate thoughts:

 

My approach, in years of studying and using microscope optics, has always been primum non nocere, first do no harm.  I fear the ammonia/hydrogen peroxide mixture would etch (or micro-etch) glass surface and perhaps attack anti-reflective coatings.  From what is recommended (again, mainly in microscopy) by optics manufacturers and microscopy practitioners, acids and bases should not be used on optical surfaces and are not necessary to successfully remove a fungal infestation.

 

This makes more sense than cold cream, but I am a bit doubtful about applicability of experience with silicon wafers.  My reluctance is theoretical, however, and not founded in my own experience.

 

To the best of my knowledge, a pharmacy will carry two only concentrations of hydrogen peroxide:  3% (or ten volume) for antiseptic purposes, and 6% (or 20 volume) for bleaching hair).  It’s easy to mistake the “volume” for percent.  (Volume refers to the quantity of oxygen evolved when the hydrogen peroxide destabilizes and breaks down to oxygen and water.). Higher concentrations of hydrogen peroxide such as 10%, 20%, and up are quite strong oxidizers and need careful handling, and would not normally ever be carried for retail sale.

 

The pH numbers alone can be misleading.  Ammonia is a strong base while the acid-stabilized pharmaceutical hydrogen peroxide is surely a weak acid; combining the two in similar quantities will yield a mixture that is less alkaline but still a strong base.  I haven’t done the calculations, however, acidic hydrogen peroxide simply doesn’t have much neutralizing power.  It still leaves us with a too-strong of a basic solution to be used routinely to treat infected optical surfaces.

(In a somewhat parallel situation, a couple of drops of concentrated hydrochloric acid in a liter of distilled water will give a solution with an impressively low pH (around 1), but only a small amount of a weak base such as sodium bicarbonate will dramatically raise the pH to approach 6 or 7.  It is not enough to know the pH and volume alone, the nature (strength) of the particular acids and bases need to be accounted for.) 

 

Cautions against using ammonia on lenses are common.  Windex is sometimes (often?) suggested as a cheap lens cleaner, especially in teaching labs.  Such recommendations are almost always tempered by caution against using Windex with ammonia, even though the ammonia is present in a very dilute form.

 

Another point:  while the chemicals used have received emphasis here, the method of application is very likely just as important.  (Maybe more so.)  My observation is that, in general, when uncommon chemicals are suggested, uncommon care is employed in their their use.  I suspect this is largely what is at work in the example of cold cream.
 

The fungus is damaging the optics.  To my mind whatever we use for cleaning should be as mild as possible to avoid damaging the surface to an even greater extent.  Lens cleaning solutions, used with friction from lens paper, perhaps followed by 70% isopropyl alcohol as a cleaner/disinfectant, should be both effective and innocuous.  Perhaps it is enough to say that this mild method should be tried, even repeated, before harsher methods are adopted.  Treatment with even a weak acid or base should ideally be reserved for cases detergent (and alcohol in more modern lenses) have failed.

 

Once the fungus is removed with detergent, mild friction, and perhaps a disinfectant, prevention is the next step.  The omnipresent fungi will be back on the clean surfaces in no time.  Removal of dust, which can be a fungal nutrient, has hopefully also made re-colonization less likely.

 

Please note that I am not an expert in this particular problem.  My remarks are based on my training, education, and experience in microscopy, microbiology, and chemistry.  In my career in microscopy, I've seen three lenses with fungal infections.  All were completely cleared of fungus through use of detergent and lens paper.  The three were so damaged that the etching affected the image and the objectives and ocular had to be discarded..

 

Microscopes are relevant here because of their many similarities to telescopes, and because the microscope are the most common scientific instrument in the world.  Microscopes are often used under trying environmental circumstances.  But the situation in telescopes is much more challenging, because the optics must be exposed to the ambient relative humidity and even dew.  Nonetheless, the fungi are the same and thus logically, the principles of prevention and remedy should be the same. 
 

What do you think?
 

Clear skies and best wishes,

 

Brian



#22 Brianm14

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Posted 18 May 2022 - 03:07 PM

A brief survey of the literature available online seems to show there are two camps of thinking on fungal infections of lenses.

 

One group seems to be fine with the use of strong chemicals (e.g. ammonia/peroxide) on lenses as a fungicide.  See this article by a chemist, “Fungus: how to prevent growth and remove it from optical components.”

https://www.ncbi.nlm...les/PMC3864060/

 

(Note:  I strongly disagree with some of this article above.)

 

The second group emphasizes the care which must be used in all handling and treating what are seen as relatively delicate coated, optical surfaces.  This is my way of thinking.  See a thoughtful discussion of this topic by a very experienced microscopist is:“Fungus and Delamination” in Optics by Paul James:

http://www.microscop...4/pjfungus.html

 

 

-Discussion

 

The first approach runs counter to all my experience and education in the use of optics.  Leading practitioners of microscopy are even doubtful of the safety of using ordinary lens paper.  This may seem a trifle extreme, until one learns that Zeiss clearly specifies one, not commonly seen, type/brand of lens paper for optical use!  (Maybe modern lenses are more robust and resistant to chemicals than I think, but I’d like to hear that reassurance from a major manufacturer of optics.)

 

After reviewing these and other sources, I still don’t see the need for a fungicide stronger than isopropyl alcohol, and instead rely principally on the removal of fungus with mild detergent and lens paper followed by drying and storage at a relative humidity of 30 - 60%.  Just IMHO.

 

It seems to be a case of, “You pays your money, you takes your choice.”


Edited by Brianm14, 18 May 2022 - 03:38 PM.


#23 Brianm14

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Posted 18 May 2022 - 03:54 PM

Brian, 

 

Thank you for the insight! I definitely was not trying to tout cold cream as a superior fungus treatment to any of the others mentioned, nor to claim to be an expert - I was just saying that it seems to work well the times I've used it, and I was interested to know if anyone might know of some negative effect that I was unaware of (like the possibility of causing further coating degradation). You are correct that cold cream is somewhat oily, but I had a plan for that, and feel I managed to clear it fairly well. The final few baths (distilled water+IPA - distilled water - methanol) were done with the elements suspended in beakers of solution via custom fixtures and continuous agitation applied via spin bars & magnetic stirring hot plate. 

 

I do have a question about your statement saying any number of emulsions could serve in place of cold cream. In this case, without looking at the ingredients, if cold cream is an emulsification of a polar solution & a non-polar solution, is it possible there's some chemical component in either the polar or non-polar part that is capable of removing the fungus? I just question the parallel to mayonnaise being a possible alternative since its an emulsion instead of the saying mayonnaise is a possible alternative because it contains a certain chemical component. I'm definitely not trying to sound rude - it's just been a while since I studied chemistry, and I know I've forgotten a lot!

 

Thanks!

Ron

Ron:

 

Great points, and I suspected you were not touting cold cream as a lens cleaner!

 

Your question about emulsions is fair and in no way rude.

 

Perhaps an emulsion -physically as such, rather than specifically cold cream-  is uniquely suited to removing fungus.  I don’t know.  I suggested mayo simply as a way of tossing out the fact that there are many emulsions in even our everyday experience.  But take that as an example of what chemical constituents could be at work here:

 

-Oil.  Oil might help release fungus from glass, and might be antimicrobial

-Vinegar or lemon juice are acidic, lowering the pH and inhibiting growth, perhaps killing vegetative fungus

-Mustard.  Should inhibit fungal growth but too dilute to kill fungus

-Salt, pepper, other (e.g. celery salt)

 

Cold cream is much more complicated with more possibilities of containing effective cleaners and antimicrobials.

 

The answer is, “I don’t know.”  
 

I strongly suspect care in the physical aspects of cleaning are strongly at work here.

 

CS,

Brian



#24 jkmccarthy

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Posted 18 May 2022 - 05:14 PM

When and if this link is back its an excellent article on fungus:

http://www.europa.com/?f

I also would like to mention fungus likes binoculars too, and the above article covers binoculars as well as

anything optical.

[...]

 

Robert

Hi Robert --

 

Clicking on the link above suggests that the domain "www.europa.com" has been abandoned and is now available for purchase.  So unfortunately I never had a chance to view the article in question, but I found this compilation of information elsewhere on the web:

 

https://digilander.l..._ras/fungus.pdf

 

... and the note at the very end that states "home page: http://home.europa.com/~telscope/binotele.htm"  made me wonder if the "fungus.pdf" document I was reading was the same document you had cited in post #11 above ?    Please take a look at your convenience.

 

In my web searching/reading, I've also run across statements by multiple authors that the 50/50 ammonia / peroxide mix was long ago recommended by Leitz (Leica) for fungus removal, but given that this recommendation (if accurately being attributed on-line to Leitz / Leica) probably pre-dates the internet / world-wide-web, I have not found any link (nor any published reference citation) to a Leitz (Leica) source document.   But I find this same attribution repeated in the "fungus.pdf" compilation above ... not sure whether to assign this attribution to Leitz (Leica) any more weight than the earlier on-line statements I've seen in discussion forum posts or blog posts elsewhere on the web ?    (And even if Leitz / Leica once did recommend this 50/50 ammonia peroxide mix for fungus removal --- maybe 4? or 5? or more? decades ago?? --- does that make the approach any more safe and advisable in 2022 relative to current best practices ?  Hmm ... arguably maybe not ....).

 

Clear Skies and Clean Lenses,

 

         -- Jim


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#25 clamchip

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Posted 18 May 2022 - 05:26 PM

Jim thats it, the article on fungus at europa.com. 

Good you found it elsewhere, it's a great article. Too bad europa.com is down, and I hope it is not

permanent, there is a wealth of telescope and binocular info there.

I'm putting the address you found and posted above right here in one of my posts so I won't loose

track of it:

https://digilander.l..._ras/fungus.pdf

 

Robert


Edited by clamchip, 18 May 2022 - 05:27 PM.

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