Stopping Mold in Binoculars (1 Viewer)

Hi! I've been enjoying the many discussions about vintage porro binoculars here on bird forums, and am so thankful for all the knowledge and experiences shared. Up for discussion: I picked up a pair of Belmont (Swift?) 7x50 binoculars at a local thrift. The image seemed fine. Only later, while looking at the objectives did I notice a tiny white circle, less than an 1/8" in diameter, towards the center of the right objective. Looking through the binoculars, I had to look for the colony to notice it was there ( I guess it is translucent in nature.)
I had inherited a pair of Zeiss compact binoculars from my Dad, which had been unused for years, here along the Coast. When I finally got around to checking them out, there was white mold completely covering the lenses! So I have a real aversion to the stuff. Last night, it came to me in a flash that there might be a way to kill the mold, if not clean it away. So this morning, in bright sunshine, I took my binoculars in one hand, and a magnifying glass in the other, and focused the sunlight into the layer of mold. The mold is dead, and slightly browned. The view through the binoculars is still fine, though the mold area is slightly more noticeable if I look for it.
I present this as an option for binoculars that are not likely to be sent in to be cleaned (the heated mold will likely be harder to remove). This is probably most useful when the mold is just starting and small. I would suggest several passes, stopping when the mold seems changed. The longer you burn it, the darker it will get, and the more noticeable it will be. My main concern was stopping the growth. I hope that this proves more useful than harmful.

Glasses said:

Hi! I've been enjoying the many discussions about vintage porro binoculars here on bird forums, and am so thankful for all the knowledge and experiences shared. Up for discussion: I picked up a pair of Belmont (Swift?) 7x50 binoculars at a local thrift. The image seemed fine. Only later, while looking at the objectives did I notice a tiny white circle, less than an 1/8" in diameter, towards the center of the right objective. Looking through the binoculars, I had to look for the colony to notice it was there ( I guess it is translucent in nature.)
I had inherited a pair of Zeiss compact binoculars from my Dad, which had been unused for years, here along the Coast. When I finally got around to checking them out, there was white mold completely covering the lenses! So I have a real aversion to the stuff. Last night, it came to me in a flash that there might be a way to kill the mold, if not clean it away. So this morning, in bright sunshine, I took my binoculars in one hand, and a magnifying glass in the other, and focused the sunlight into the layer of mold. The mold is dead, and slightly browned. The view through the binoculars is still fine, though the mold area is slightly more noticeable if I look for it.
I present this as an option for binoculars that are not likely to be sent in to be cleaned (the heated mold will likely be harder to remove). This is probably most useful when the mold is just starting and small. I would suggest several passes, stopping when the mold seems changed. The longer you burn it, the darker it will get, and the more noticeable it will be. My main concern was stopping the growth. I hope that this proves more useful than harmful.

Click to expand...

WELCOME to BirdForum:

Please keep in mind that not all molds are created equal—there are about 250,000 species. It seems you MAY have been fortunate to have caught it early. When some molds are cleaned away, they leave their etch marks in the glass from where the have been munching away. Some PhDs have said the molds do not have roots. That’s information from a textbook somewhere. Perhaps they don’t have roots, but sometimes—something—has been digging out the surface. In some cases, that is much worse than leaving the mold alone, as the many sparkles of the microscopic fractures scatter light and causes a loss of contrast in the offending side.

Just a thought,

Bill

Hi,

Welcome to BF and thanks for posting your find.

This sounds like an interesting method to kill early fungus - ultraviolet light is known to kill it too but getting that in sufficient intensity to the fungus on the inside of an instrument is usually not very easy since transmission ratios of optical glass are often not so great for hard UV.

Could you please take an image of the mold as is for reference and have a very occasional look at the bins to verify no further degradation has taken place? We would love to hear about this from you in a year or two - and of course all the time in between on other topics!

Joachim

I have lived much of my life in the tropics and hot climates since I bought my first camera. In Kowloon, many moons ago I found containers with heaters and silica gel that operated on 220v supply.

I cannot find the same article now but there are other rechargeable desiccants for sale on the Internet.

If I want to clear vapour from lenses I put the recharged desiccant box in with the glass and a humidity meter inside a sealed plastic box in an airing cupboard. Arbitrarily, I leave it there for a week. The desiccant should absorb the moisture.

In humid climates I stored my lenses with silica gel in plastic boxes.

Baader Optical Wonder Cleaning Fluid claim it protects against fungus, so it might be worth cleaning exposed with this after drying out the optic.

The only problems I foresee are that the heat may damage the balsam between the objective elements and if really hot it could crack an objective.

Strong UV can also reverse the browning in thorium containing glass.

The mold feeds on protein, I think, such as dust mite particles, fingerprints etc. I think it takes chemicals from the glass as nutrients. This leads to the spider like growth patterns.

Certain older lenses such as Zeiss Ikon 1950s had terrible balsam that failed rather quickly. All my lenses on one camera failed. But I don't know if this balsam was used in binocular objectives.

I presume that the mold is inside the optics.

In the U.K storage has to be above 13C and humidity less than 60%, preferably 40% or less. I prefer binocular storage outside cases, as these seem to make the problem worse. I often just throw away suspect cases.
A waterproof case for a 90mm Maksutov had lots of mold even though the scope cleaned up fine externally and has no internal damage. This was a new scope but maybe stored two years or so.
I carefully smell all cases and if I suspect problems I keep them well away from optics.

Just a couple of additional suggestions regarding killing mold with a magnifying glass: 1) Use the magnifying glass to monitor the mold before and during the process (Mine is 5", and made of glass). 2) More precise control will be had by holding either the magnifying glass or the binoculars with both hands, while the other glass is clamped in place.

A 5 inch magnifying glass packs quite a punch and the heat could be considerable.

If you have a large range infra red thermometer I wonder what temperature it reaches?
If over 200C I'd be careful.

Usually large magnifiers magnify less than small ones, but the concentrated heat can be high.

I agree that there is a risk in using a magnifying glass (MG) to kill mold on the lenses. After the post, and after the feedback, I did some experimenting. I discovered that my one-handed shakiness had been the saving grace in the situation. Simply put, by keeping the MG moving, you keep the concentrated sunlight from building up heat in one place in an instant.
By learning to control the heat from the MG, you reduce the risk to your binoculars.
You have to learn to burn in order to know how to not-burn. In a fire-safe, breeze-free location, put some pieces of newspaper on a fire-proof surface. With the MG between the paper and the sun, center the field of focused sunlight on a piece of paper, moving the MG until the field is a circle. You'll notice that there is a bright ring at the circle's edge.
Hold the ring on the paper, and see how long it takes for the paper to catch fire. Do this many times. Move the MG away from the paper: the ring gets smaller and more intense. Repeat the burnings. Shrink the ring to a dot. You will have noticed that the ring/point sets fire to the paper immediately. (>450F)
Now move the MG so that the ring expands and shrinks, moving through the focal point. The paper should never catch fire as long as the ring never stops moving. This is how not-to-burn.
We don't want to burn the mold, we just want to kill it. Boiling should do it. (210F). So now put some drops of water on a glass surface like a hand mirror. Hold the ring of heat on a drop. Instant vaporization. Now practice moving the focal point of the MG through the drop. I use sort of a bungee movement: lower the MG to center the circle on the drop, then slowly spring away from the drop, pulling the focal point through it quickly, or sideways to avoid the focal point. If the drop shrinks, but doesn't evaporate immediately, then you've controlled the heat to about the boiling point. If it takes at least three passes to boil off the drop, then you're ready for your binoculars!
(Stop passing through the mold when it "changes". Examine it. Does all of look transformed? We don't want brown/black: we want clear, not white. And my mold was a small spot. I have no idea what will happen with a large patch.)
Good Luck!