Fighting fungus

Gerd · 2009-08-18T16:44:13+00:00

Hallo, ich habe mir, sozusagen als Beifang zu einem Vergrößerungsobjektiv, einen Fungus eingefangen. Auf der Suche nach einer Lösung bin ich dann im Netz üb...

Gerd

Hello, I’ve picked up a bit of fungus, sort of as a bonus when buying a close-up lens. Whilst looking for a solution, I stumbled acrossthis article online, in which someone describes how they tackle fungus. The article is in English and I’m so plagued by underexposure to chemistry that I’d rather ask for your advice before I go hunting for the stuff. The man uses

[size=2] a 50-50 mixture of ... : hydrogen peroxide and ammonia.[/size]

I assume that means hydrogen peroxide and ammonia. (Although I always thought ammonia was a gas. Never mind.) Can anyone tell me where I can get hold of this stuff in small quantities and what I need to ask for? Do I need to be careful with it, or is it harmless? How do the metal parts and the lens coating react to the chemicals? What about my skin and clothes? What do I need to bear in mind when disposing of it? Thanks in advance Gerd

Wolfgg

Hi Gerd, It seems that Leitz recommends making a mixture of 94% distilled water, 2% hydrogen peroxide and 4% ammonia, and soaking the lens in it for at least an hour. Keeping the lens at 60–70°C for 24 hours is also said to help. Regards, Wolfgang

Wolfram

Hi Gerd, You can get both at the chemist’s. Hydrogen peroxide is mainly used for bleaching. (That’s where 80% of blondes come from...) :( We used to use ammonia to develop blueprints. I’d only use either of them outdoors. Ammonia in particular has a rather pungent smell even at room temperature, and the fumes are highly irritating and not entirely harmless. :lol: Be sure to wear rubber gloves. They aren’t exactly toxic to the skin, but they dry it out very badly. And they bleach fabric. Chrome has no problem with this stuff. With lacquer, usually only after prolonged contact. Whenever possible, I’d take the lenses apart and treat the individual elements. (The fungus usually settles on the inside) Simply wipe firmly with a damp, SOFT cloth. Or, whilst still fitted, rub with a cotton bud. The question is whether the fungus has already attacked the coating. If so, that won’t do much good. :angry: Have fun tinkering, Regards Wolfram

Gerd

Thanks, I'll pop into the chemist's in the next few days. Gerd

Wolfram

Hello Gerd, Here is an extract from the ZEISS website: LINK "How can fungus be removed? Note : To prevent contamination, Carl Zeiss does not accept any equipment affected by fungus. Clean affected surfaces with a cotton swab soaked in disinfectant. You can make the cotton swab yourself by wrapping cotton wool around a toothpick so that it forms a cone-shaped pad at the pointed end of the stick. Make sure not to use impregnated or perfumed cotton wool, but rather, for example, eye cotton wool. Rub corroded optical surfaces vigorously with an optical cloth. Cigarette ash can serve as a polishing aid here. If optical surfaces are heavily encrusted, the optical components must be replaced. Inside the device, fungal infestation can only be removed after dismantling.” So you don’t necessarily have to resort to the “harsh methods”. “Keeping it warm” is unlikely to be very successful: fungal spores can survive even in space and in geysers.... . Besides, you’d probably have to clean the entire lens, including the mechanics, and re-grease the worm gears. The question is whether you shouldn’t just buy a new lens, as the optical performance has certainly already suffered and you might end up spreading the infection around the house. Regards Wolfram

Wolfgg

Which source is reliable? Read for yourselves: "The vegetative cells of bacteria and fungi are killed within 5–10 minutes at temperatures as low as 60°C. Yeast and fungal spores are only killed at temperatures above 80°C, and bacterial spores at temperatures above 120°C (15 mins)." http://books.google.com/books?id=m9cKJgRxP...t&resnum=29 Best regards, Wolfgang

Wolfram

Hello Wolfgang, I don’t see any contradiction there. You wrote above: “Keeping the lens at 60–70°C for 24 hours should also help.” Now: “Fungal spores only die above 80°C...” At 70°C, the fungi might be dead. But some spores (the "spawn") survive that. Then you’ll have fungi again a few weeks later. Furthermore, at high temperatures there is a risk that any grease in the thread could liquefy and settle on the optics. Then the magnifying lens would have a soft-focus effect. Good luck focusing on the grain. First of all, you’d need to know how it reacts to different temperatures. More details about the fungus at http://de.wikipedia.org/wiki/Glaspilz It is quite funny, though, that such a lowly creature can ‘nibble away’ at hard materials like glass. It probably secretes some kind of special acid during digestion. Regards Wolfram

Wolfgg

Hello Wolfram, I think that if you don’t take the lens apart, you’re heading down a rather dangerous path anyway. Nature has designed the spores to be much more resilient than the fungus itself, and they’re bound to get as far out as possible; they might even be sitting in the grease, protected from any attempts to wash them away. The important thing is simply that the dead fungus can no longer produce new spores, otherwise you might end up putting your entire collection of lenses at risk. Unfortunately, reliable information on this subject is hard to come by; even on the question of whether the fungus feeds on the glass or the coating, opinions are divided. Regards, Wolfgang

Wolfram

Hello Wolfgang, You’re right, in a way. It’s all or nothing. If the glass fungus – and ‘fungus’ is just the umbrella term for fungi, not the specific organism shown in the picture – isn’t causing any issues, I’d ignore it and just make sure it doesn’t spread further due to damp and heat. So, once you’ve finished your work, always take it out of the lab and put it in a cosy, dry spot. Especially since, if I’ve understood correctly, the fungus ‘corrodes’ the glass surface. According to Wikipedia, it doesn’t feed on the glass but on lint and paint. It apparently uses the pane more as a ‘urinal’. I don’t think cleaning it helps much either. Opinions are even more divided on the risk of infection. I’d at least disinfect the lens from the outside. Heating it might be one way to remove any residual moisture. My suggestion would be to throw it away or try to live with it. Regards Wolfram

StefanCaspari

Hi Gerd! I’ve found another interesting site. Visit my homepage It’s important to note – and this is emphasised – that spores are everywhere in the air. You can’t prevent that; that’s not the problem. It becomes a problem when these spores encounter environmental conditions in which they can germinate. And that usually means: damp, warm and dark. Conversely, you can stop ‘mature’ mould by depriving it of the conditions it needs to survive. So: bright (ideally with some UV light for a while) and dry. I would strongly (!) advise against attempting to take the lens apart and clean it, unless it is a model of the very lowest quality – in which case you might as well buy a new one straight away. All I can say is: keep your hands off a Rodagon etc.!! You’d most likely have to have it re-calibrated afterwards. If that’s the case, I know a camera/optics specialist here in Munich who does this professionally. Warm regards from Munich: Stefan

John

The reason Zeiss doesn’t accept mouldy items is because spores have an unpleasant tendency to spread easily. So I can only advise you to either decontaminate the lens or bin it. You won’t manage it with heat alone unless you have the means to keep the dismantled lens in steam at a temperature of at least 90°C for a day – and I won’t even get started on autoclaving. However, I had the chance to speak to a technician at a microscopy workshop. There is a method; whether you can implement it or whether the effort is worth it is up to you to decide. Remove the affected lens and clean it in an ultrasonic bath on a low setting. Alternatively, you can of course clean it thoroughly using other methods, preferably with petrol with a boiling point <44°C. Use a cotton ball (lint-free eye cotton) for this, and wipe gently without applying pressure. If you have sensor cleaning wipes, these will work too, of course. With both methods, rinse the lens thoroughly with Aqua Dem afterwards, then rinse again with petrol and leave to dry. Wear powder-free gloves (nitrile washing-up gloves are fine) for all work, including when handling the cotton wool. The chemicals and cotton wool are readily available at the chemist’s if you have no other sources. However, bear in mind that petrol is flammable. So far, so good, apart from the dismantling part. In the next step, the inside of the objective tube must be illuminated with UV light for 4–5 hours. It is best to use a UV LED or UV diode with a lens for enlargement of the beam angle. You will also need the components to get everything working; some knowledge of electronics is required to assemble the circuit. Take care with your eyes!!! Afterwards, apply a little fungicide (available from a chemist) to an inconspicuous spot inside the tube and reassemble everything. (Note: A friend of mine has successfully tested the fungicide from Caparol, which is available in DIY stores in the paint section) Depending on the extent of the fungal infestation, some damage may naturally remain; at the very least, the contrast will have suffered. Best regards