[c.a.m]

I had posted the following in another thread, and think it might be of general interest to warrant a separate post.

Insight into the environments that favour fungus germination and growth may be found at the following references. The first paper also reports an approach and procedure for removing fungus.

I. Cordero, Fungus: How to prevent growth and remove it from optical components, 2013
Fungus: how to prevent growth and remove it from optical components

S. Block, et al, Humidity and Temperature Requirements of Selected Fungi, University of Florida under contract to the US Air Force Aeronautical Systems Division, ASD Technical Report 61-490, 1961
https://apps.dtic.mil/dtic/tr/fulltext/u2/268093.pdf

In summary, the second reference concluded that "Spore germination was usually prevented when the relative humidity was below 70 percent regardless of temperature."

- Craig

[CarlosU]

In summary, the second reference concluded that "Spore germination was usually prevented when the relative humidity was below 70 percent regardless of temperature."

I totally endorse this statement. I fought with fungus growth for a long time, even loosed two lenses that went beyond repair. The definitive solution came when I began to control principally humidity over other variables. I did this by storing my lenses and cameras inside a cabinet in which I put a "hot rod" (ceramic covered electric resistance) that gives a constant heat source to the inside, lowering humidity (low cost DIY solution, by the way).

I normally have values that go from 40% to 55% RH and 28°C to 32°C.
Initially I had some concern about the effect on mechanical parts (dry lubrication in bearings and helicoids, dryness on rubber rings and grips) but after some years using this method I have not seen any sign of problems and had zero fungus growth. That is living in a place where 75-85% RH is common around the year.

[gordon_l34]

Hi All,

I posted a reply in the post titled "Is Japan the Fungus Capital of the World?"

Regards,
Gordon.

[photoptimist]

This Dew Point Calculator provides estimates of four types of environmental risks based on temperature and relative humidity.

[Take-5-JB]

One has to think about this as the survival modus operandi for fungi and spore forming bacteria. If the environment is warm and humid, they proliferate. If it is hot and low humidity, or cold and dry, it is not in the optimal zone and the emergent organisms die, but the spores they produced while living are existing in near perpetuity. Except for some extreme locations where the environment can kill or denature the spores, you will find fungi and spore forming bacteria. Desiccation is the general control program. If your equipment is in an air conditioned or otherwise lower humidity situation and you take them out in the world to use, it would be wise to keep some desiccating packs in your backpack or case. Putting the equipment in the presence of desiccants or drying rods and the like after being out in higher humidity is good tactic to prevent the spores from activating. The spores are almost always present. Here on the SE coastal lowcountry, doctors will tell you we live in a breeder reactor for sinus, ear, nose, throat and lung related fungal and bacterial infections (i.e., sinusitis). Photoptimist has a good tool there, as the higher the dew point temp, the higher the humidity, the more likely you will activate spores.

An aside to elucidate the point...A friend was a Green Beret with three tours in Vietnam fighting in the mountains near the Laos border. He said it was hot and humid in the day and just below the dew point at night so you sweated all day and dew dropped on you all night, or it rained. They were never dry and cool. They constantly suffered from jock itch, athletes foot, ear and throat infections, and other ailments. Temp & humidity was perfect for fungal spore activation and the organism ran wild.

JB

[les3547]

Even though we live just a few miles from the Pacific, the humidity in my house just about never reads above 50%. Nonetheless, I use silica gel dehumidifiers in my bag like first two below that are inexpensive and easy to maintain:

Barska — refreshes in the microwave

Eva — rechargeable type

Ironwood Pacific — gun safe/air dryer type

[ZombieArmy]

One has to think about this as the survival modus operandi for fungi and spore forming bacteria. If the environment is warm and humid, they proliferate. If it is hot and low humidity, or cold and dry, it is not in the optimal zone and the emergent organisms die, but the spores they produced while living are existing in near perpetuity. Except for some extreme locations where the environment can kill or denature the spores, you will find fungi and spore forming bacteria. Desiccation is the general control program. If your equipment is in an air conditioned or otherwise lower humidity situation and you take them out in the world to use, it would be wise to keep some desiccating packs in your backpack or case. Putting the equipment in the presence of desiccants or drying rods and the like after being out in higher humidity is good tactic to prevent the spores from activating. The spores are almost always present. Here on the SE coastal lowcountry, doctors will tell you we live in a breeder reactor for sinus, ear, nose, throat and lung related fungal and bacterial infections (i.e., sinusitis). Photoptimist has a good tool there, as the higher the dew point temp, the higher the humidity, the more likely you will activate spores.

An aside to elucidate the point...A friend was a Green Beret with three tours in Vietnam fighting in the mountains near the Laos border. He said it was hot and humid in the day and just below the dew point at night so you sweated all day and dew dropped on you all night, or it rained. They were never dry and cool. They constantly suffered from jock itch, athletes foot, ear and throat infections, and other ailments. Temp & humidity was perfect for fungal spore activation and the organism ran wild.

JB

I've never heard of a person accruing fungus on a lens that was being actively used, regardless of the circumstance. I feel like there's another requirement that needs to be met for these fungus to infest.

[Take-5-JB]

ZombieArmy,

Nothing is absolute. There is an increased propensity for an event to occur as the convergence of supportive conditions occurs. I am glad you and those you know have been able to avoid problems. The more expensive the equipment, the better it is to employ insurance prophylactically, i.e., a purchased policy and/or actions that provide a modicum of protection. A food substrate can promote the problem. Internals of lenses may have resins, or glues, which are organic based, or if the lens was improperly handled during service (jeweler gloves or high quality wiping cloths not used) there may be skin oils present. In addition, darkness, or lack of direct sunlight, can allow/support microbe growth. Generally, UV light negatively impacts microbes. Actively used equipment will see more UV light than stored equipment. If one is working in an Equatorial area during rainy season, it would be wise to have a moisture control regimen to help thwart fungal invasion of the equipment during short term, or longer term, storage of the equipment after the expedition.

Continued success and enjoyment of your photography!

JB

[c.a.m]

In light of the ongoing interest in fungus growth on lenses, I'd like to add this reference article from the Canadian Conservation Institute. It deals specifically with mould -- a type of fungus. The article describes the conditions for mould growth and its prevention.

https://www.canada.ca/en/conservation-institute/services/conservation-preser...-recovery.html

To inhibit or prevent the growth of mould over a long term, the authors recommend keeping the relative humidity below 65% or even 60%. While moisture is the key factor, there are other considerations such as air circulation and temperature.

- Craig

[ehrwien]

While moisture is the key factor, there are other considerations such as air circulation and temperature.

Light (or the abscence thereof) plays no role?

[c.a.m]

Light (or the abscence thereof) plays no role?

According to the paper by the Canadian Conservation Institute:

"Light

The role that light plays in mould growth is not well defined. Some studies of certain moulds have shown that light affects moulds in the following ways: it may inhibit growth, affect the direction and rate of growth, and affect the production of certain compounds (toxins and volatile organic compounds). Light can also affect the reproductive processes of mould. For some species, light is essential, for others, it is not required.

Objects stored in the dark to reduce the rate of deterioration are not more susceptible to mould growth. Light is not a critical factor for controlling indoor fungal growth: nutrients, moisture and temperature are the critical factors (Shaughnessy et al. 1999). However, mould growth may go undetected for long periods of time if routine inspections of storage areas or areas where human occupation is minimal are not regularly carried out. Also, if there is less air circulation in dark storage areas, it may contribute to mould growth."

I'm not an expert in this field, so I can't say whether the statement concerning certain moulds are applicable to all fungi in general.

- Craig