old filter with fungus

hi there !

i found an old nikon achromat filter in a bag at home , with fungus. 

asside from sun bathing, which kind of substance would treat the fungus: vinagre ? diluted hipoclorite solution  ? 

anybody with good recepie for fungus treatment ?????

thanks for any input !

andre. 

I don't know what coatings are used on those old filters but my guess is that anything you use will remove the coating and also the fungus itself ay have etched the coatings.

E.J. Peiker wrote:I don't know what coatings are used on those old filters but my guess is that anything you use will remove the coating and also the fungus itself ay have etched the coatings.

its an achromat, 3x . works like a close up lens.
i think i would not be worried about coatings here......

i do know some bathing with chemicals are/were used to fungus treatment..... bu i don not recall exactly how its  done....

photographers over a certain age, from the good old analogic times  might have the recepies i would guess      .... 

andre.

Still, fungus will etch the filter so it may not be possible to restore it to perfect condition.
This article recommends ammonia:
https://petapixel.com/2016/09/29/remove-fungus-lens/

E.J. Peiker wrote:Still, fungus will etch the filter so it may not be possible to restore it to perfect condition.
This article recommends ammonia:
https://petapixel.com/2016/09/29/remove-fungus-lens/

true... depending on the degrre of fungus corrosion, to the bin the equipment goes .....

some other substances like hypoclorite were used i think, but i really dont remember.....

thanks for the link! i will give a look at it ....

andre

E.J. Peiker wrote:Still, fungus will etch the filter so it may not be possible to restore it to perfect condition.
This article recommends ammonia:
https://petapixel.com/2016/09/29/remove-fungus-lens/

ok,

bought and used amonia solution  and hidrogen peroxid as used in the article.

amazing, the filter is cristal clean in terms of fungi... regarding coating i can not judge by naked eye .

i will test it soon.

andre.

E.J. Peiker wrote:Still, fungus will etch the filter so it may not be possible to restore it to perfect condition.
This article recommends ammonia:
https://petapixel.com/2016/09/29/remove-fungus-lens/

bubbles emerge like an alka seltzer tablet  

fungus is being attacked !!!!!!!!!!!!

it works.

thanks ej !

Fantastic news!

andre paul wrote:hi there !

i found an old nikon achromat filter in a bag at home , with fungus. 

asside from sun bathing, which kind of substance would treat the fungus: vinagre ? diluted hipoclorite solution  ? 

anybody with good recepie for fungus treatment ?????

thanks for any input !

andre. 

Hi Andre,

Be very cautious when applying strong alkalis like bleach (Sodium hypochlorite) to glass as they tend to erode the surfaces making then cloudy - not ideal for good optical results!!

Just a theory of mine - I have examined "fungus" lenses under the microscope many times, and have observed mainly chemical erosion tracks etched into the MgF2 coatings. Having worked with a few chemical compounds and their interactions with glass surfaces, I have always suspected that the "fungus" effect we often see on older lenses might be due not to a biological organism (such as a fungus) but rather to the hydration of the magnesium fluoride coatings applied to the lens as an anti reflection measure.

MgF2 crystals used in the chemistry lab. are sold in air tight containers with the warning "keep tightly closed to avoid atmospheric moisture contamination" printed on the jar.

When compounds like magnesium fluoride become hydrated their neat crystal lattices can become disrupted by the inclusion of water molecules within the otherwise regular lattice structure. Lens manufacturers probably applied an anti hydration coat on top of the MgF2 layer to stop this. Hydration would cause the surface of the MgF2 to "spall" off as it expands, revealing more MgF2 surfaces to become hydrated, leading to spidery hydration tracks as the moisture creeps under it.

Whatever the answer, the lens manufacturers would have probably kept their particular anti hydration treatments a closely guarded company secret.

Next time you have a "fungus" encrusted lens handy, put it under a good microscope and you will see crystalline tracks and not fungal filaments.

As I say - its just a theory of mine, but it would be well worth further investigation by keen person out there with the time and facilities!

By the way good lenses today use other AR compounds and processes - will be interesting to see if these cure the problem in the future.

PS: Whatever the answer - Dust + Moisture isn't a good combination inside a lens and would provide a food source if biological agents were found to be involved.

John S

kiwijohn wrote:

andre paul wrote:hi there !

i found an old nikon achromat filter in a bag at home , with fungus. 

asside from sun bathing, which kind of substance would treat the fungus: vinagre ? diluted hipoclorite solution  ? 

anybody with good recepie for fungus treatment ?????

thanks for any input !

andre. 

Hi Andre,

Be very cautious when applying strong alkalis like bleach (Sodium hypochlorite) to glass as they tend to erode the surfaces making then cloudy - not ideal for good optical results!!

Just a theory of mine - I have examined "fungus" lenses under the microscope many times, and have observed mainly chemical erosion tracks etched into the MgF2 coatings. Having worked with a few chemical compounds and their interactions with glass surfaces, I have always suspected that the "fungus" effect we often see on older lenses might be due not to a biological organism (such as a fungus) but rather to the hydration of the magnesium fluoride coatings applied to the lens as an anti reflection measure.

MgF2 crystals used in the chemistry lab. are sold in air tight containers with the warning "keep tightly closed to avoid atmospheric moisture contamination" printed on the jar.

When compounds like magnesium fluoride become hydrated their neat crystal lattices can become disrupted by the inclusion of water molecules within the otherwise regular lattice structure. Lens manufacturers probably applied an anti hydration coat on top of the MgF2 layer to stop this. Hydration would cause the surface of the MgF2 to "spall" off as it expands, revealing more MgF2 surfaces to become hydrated, leading to spidery hydration tracks as the moisture creeps under it.

Whatever the answer, the lens manufacturers would have probably kept their particular anti hydration treatments a closely guarded company secret.

Next time you have a "fungus" encrusted lens handy, put it under a good microscope and you will see crystalline tracks and not fungal filaments.

As I say - its just a theory of mine, but it would be well worth further investigation by keen person out there with the time and facilities!

By the way good lenses today use other AR compounds and processes - will be interesting to see if these cure the problem in the future.

PS: Whatever the answer - Dust + Moisture isn't a good combination inside a lens and would provide a food source if biological agents were found to be involved.

John S

thanks john! 
i like your input here .... you are much more into chemistry and physics then i am , thats for sure 
the amonia and hydrogen peroxide made my filter kind of clean, i did not use the strong alcali hypoclorite .....
i don't know if if has destroyed the coatings however ....
would yu think an ether  would be of some benefit ?  

thanks again!
andre.

Ammonia is an excellent solvent and Hydrogen peroxide will zap any living thinks on your filter for sure. If it is fungus stuck to the glass they will be history pretty quickly!
A safety thought here - Ammonia is bad enough, but be careful not to get any peroxide onto unprotected fingers - if you do, after a while it will feel like you have dozens of needles sticking into them! Its agony! Its really nasty stuff!! Goes without saying that eyes would be permanently damaged if you splashed them too.

Disposing of peroxide soaked cotton wool is a headache too. High concentrations of H2O2 can cause cotton (or paper) swabs to spontaneously combust. You are probably using standard 18% H2O2, which is PROBABLY safe....

PS: As EJ says, if the surface has been etched into then only repolishing the filter (and re-coating it) will be the remedy.

John S