Lens Eating Fungi

2/23/98

Microscopists:

I've been asked by a colleague what if anything I knew about the problem

of fungi (presumably) that can grow on and etch the front lens of

microscope objective lenses, making them useless for any work.

This problem may be correlated with tropical or near-tropical

environmental conditions.

I couldn't help him at all with any substantive information, but I'll bet

this newsgroup can provide answers or leads.

Any help would be appreciated.

TIA,

M. Nesson--

_______________________________________________________________________

Michael Nesson, Ph.D. Department of Biochemistry & Biophysics

2011 Ag&LS, Oregon State University, Corvallis, OR 97331-7305

(541)737-5245 FAX:(541)737-0481 nessonm@ucs.orst.edu

Be warned that this problem not only occurs in tropical, humid climates,

Wellington , New Zealand can hardly be called tropical. We experienced

this problem on a surgical microscope .The problem appeared over

winter/early spring when the weather was damp but hardly tropical.

Luckily we caught the problem before any permenant damage was done. The

microscope which is not used to often is now stored in a dry atmosphere

and inspected regularly as once the problem has occurred it is far more

likely to reoccur (residual spores etc)

Peter Smith

AgResearch

Upper Hutt

New Zealand

Are you people *sure* this problem is biological, caused by a fungus?

Might it not be a devitrification of the glass?

I worked several years ago with a student in Art Conservation from the

nearby Winterthur museum. Her specialty was lockets which contained

pictures behind glass. The glass in these often had the exact problem you

describe. Although the stuff on the surface of the glass looked like a

growth of some kind, it was actually a gel of glass material in water. She

told me this is common knowledge in her field, and is in all the

textbooks. One giveaway that this is something done by the glass is that

it only happens to flint glass, not to crown. You'd think a fungus would

do it the other way around; what would preferentially grow on a material

that is 10 or more percent lead?

Is there a newsgroup or mailing list for optical repair to which we

could submit this question? If there is no fungus, then fumigation won't

help, and dessication is the only preventative.

Robert Wieland wieland@me.udel.edu

Electron Microscope Specialist University of Delaware

Devitrification can be identified using SEM (with appropriate precautions to

eliminate charging). Sometimes, the devitrified areas grow radially from a

point of nucleation. In any case, there is crystallization of the glass that

will appear different from organic growth. Devitrification is a very slow

process at room temperature which would be a reason to expect to find it only

on very old optics.

Jeff Hurd

hurdj@us.ibm.com

We have encountered the same type of fungus here in New York City, growing

on the surface of a diamond knife. As the fungus approached the sharp edge

of the knife, that portion was ruined. The precipitating cause seemed to

be a knife storage box which was air tight, and our own carelessness. If

the knife was placed into the box wet, and the box shut before the knife

had dried, the fungus grew. Over time, the fungus eventually attacked the

entire knife surface, despite efforts to dry the knife after each use.

David Hall

Department of Neuroscience

1410 Pelham Parkway

Albert Einstein College of Medicine

Bronx, NY 10461

phone (718) 430-2195 FAX (718) 430-8821

The Midwest is not the tropics, but we have have two experiences with fungi

growing inside of presumably sealed microscope components. In both

instances, the fungus grew inside of the prism/beam splitting chamber of

a Leica OrthoPlan II. The front-mirrored surfaces were covered with the

fungus which then became visible when using the microscope. Besides being

annoying, it obscured fine detail. The entire assembly had to be sent back

to Germany for cleaning. Leica was most gracious about doing this gratis

but now, three years later, the fungus is back. Apparently, it grows on the

front surface mirrors which must be replaced.

I have heard that in the tropics, optics (binoculars, or "sealed" optical

systems) should be stored in a desiccated environment when not actually

being used. Otherwise, fungi get into the "sealed" lens components, grow

and etch the glass surfaces or even grow on the lens cement until they

completely fill the optics.

My own thinking on this matter would be to periodically "gas" the sensitive

components using formaldehyde gas. For example, remove the optics, place in

a zip-lock bag with some formalin (38% formaldehyde) and allow gas to

permeate the optics. HOWEVER, we need to have some input from microscope

manufacturers since the formaldehyde may affect some components inside the

lenses. On the other hand, left alone, the lenses will surely be ruined by

the fungi.

####################################################################

John J. Bozzola, Ph.D., Director

Center for Electron Microscopy

Neckers Building, Room 146 - B Wing

Southern Illinois University

Carbondale, IL 62901

U.S.A.

Phone: 618-453-3730

Fax: 618-453-2665

Email: bozzola@siu.edu

Web: http://www.siu.edu/departments/shops/cem.html

I would love to find out if this would work! Once discovered, keeping the

affected glass optics dry prevents spread of the fungus, but it gets going

again if rehydrated, I think.

My experiences with containers and humidity has led me to a number of

conclusions. First, zipper-type plastic bags don't really keep out

moisture all that well for very long. Don't rely on them. And I'd bet

the formaldehyde vapors would permeate OUT of the bag, as well, so don't

do this at home. I am ready to stand corrected, of course.

Secondly, Parafilm does an amazing job of sealing things up. It took me a

long time to figure out that Parafilm wrapped around the lid of any old

jar will keep indicator dessicant blue for years. I trust it, now. My

camera equipment is in a peanut butter jar with dessicant and Parafilmed.

(Anyone remember my rant about peanut butter jars for storage a year or so

ago?)

Next, of all the commercial sealable food storage containers out there, I

have found Tupperware brand to be the best at sealing out humidity. I

have had a couple of hilarious Tupperware parties for scientists where the

poor salesperson was bewildered by our refusal to play the games, and our

discussion of pathology and oceanography. It's easier to go to the local

supermarket for Rubbermaid or equal brand, but they just don't do the job.

And something I found out the *hard* way - Drierite (CaSO4) can be

corrosive, so we have switched to silica gel.

We sometimes put a "head" of N2 gas before sealing things.

My $.04 (twice as long as it should be).

Tina

http://www.pbrc.hawaii.edu/bemf/microangela

****************************************************************************

* Tina (Weatherby) Carvalho * tina@pbrc.hawaii.edu *

* Biological Electron Microscope Facility * (808) 956-6251 *

* University of Hawaii at Manoa * http://www.pbrc.hawaii.edu/bemf*

I have had this problem with 35mm camera optics and it's not pleasant when

it happens. Photographers working in humid, tropical conditions (which

pretty much typified the southern Illinois summer climate when I lived

there) often describe this problem. I see no reason why the same problem

wouldn't occur on microscope optics.

I eventually had to replace lens elements in a high-priced macro lens.

Other than trying to keep the lenses in a low-humidity environment (i.e.,

storing in containers with silica gels), I'm not personally aware of any

preventative for fungus growing on lens surfaces or lens coatings. Nor,

unfortunately, am I aware of any cheap fixes.

Maybe some other people have better solutions.

Randy Tindall

Electron Microscope Laboratory

Box 3EML

New Mexico State University

Las Cruces, NM 88003

rtindell@nmsu (work)

nrtindall@zianet.com (home)

Randy it is a very common problem for fungi to get into the layers that

make up a lens. In my experience it is incurable,(Anyone please correcr me

if there is now something that I don't know about). In my 25+ years in the

humid tropics I never had the fungi problem while other people around me

did. I have always attributed this to the fact that I never covered my

microscope, prefering to let the air circulate around it. I know that it is

considered sacrilage not to cover your microscope but my microscopes have

certainly outlasted numerous others and never had the dreaded fungi.

Christine Lee,

Senior Scientific Officer,

Veterinary Pathology,

University of Queensland.

C.Lee@mailbox.uq.edu.au

The LM maintenance section at our local (latitude 19) University years ago

researched that topic. Most of the microscopes are kept in airconditioning

and then no precautions are required but for the Coral Sea island research

station they enclose a teaspoon of paraformaldehyde powder in a small paper

bag within the microscope case. This protects the microscope for a year or

two and apparently has no ill effect on lenses and the mechanical parts.

Another alternative are the "plug-in and forget" new desiccating cabinets.

They keep relative humidity below 20%; a true innovation. I must declare an

interest: ProSciTech sells these.

Cheers

Jim Darley

ProSciTech Microscopy PLUS

PO Box 111, Thuringowa QLD 4817 Australia

Phone +61 7 4774 0370 Fax: +61 7 4789 2313

Great microscopy catalogue, 500 Links, MSDS, User Notes

**************************** www.proscitech.com.au ***

Credits to all that have contributed to this thread;

But does anyone know the name of this type of fungus?

What type of glass does it grow on and what component of the glass is so

attractive to it?

Before my business became overwhelmingly active I used to restore old

optical systems for historical exhibition.

I no longer have time for that now but after years of seeing great optics

ruined by this fungus I am glad others have raised this topic.

Hopefully I'll learn more about it.

Dan

dan@bioptechs.com

One of the fungi that does this is Aureobasidium pullulans, it is

also seen often growing on tile grout in bathrooms. My best guess

it is using carbon in the coatings or cements, or thin oil films that

form from the air.

Russ

RZS@plantpath.wisc.edu

In my past years as a microscope optical engineer, I tend to agree with Russell. The fungi always attacked the soft internal lens coatings, not the hardened coatings of exposed lens. If there is a problem on the outside of the objective, I would first think of scratch damage or similar. Whilst the fungi can be successfully removed from the lens elements, it also means removing the soft coatings which in turn compromise the chromatic correction of the lens. The coating can be re-applied, however it is expensive. It is a popular practice for many manufacturers of sea going binoculars to charge the body with nitrogen and I know that at least one microscope manufacturer did this with special order scopes to countries at risk. Also tried was an additive to the coating material which, again available on special order, seemed to increase the life of the optics.

The tips on prevention already discussed do go a long way in minimising the risks. Some coatings seem to be better in this regard than others. Also, to complicate matters more, there are variations in the quality of the coatings from scope to scope.

Roger

Roger Wallis

General Manager

Optiscan P/L Confocal Microscopy

PO Box 1066

Mt. Waverley MDC

Victoria 3149 Australia

Tel: (61) 3-9562-7741

Fax: (61) 3-9562-7742

e-mail: rogerw@optiscan.com.au

URL: http://www.optiscan.com.au

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