Fungus on lenses and Silica gel

[Nathaniel]

I have stared this thread as it is specific to the effect of silica gel in preventing fungus/mould attacks. It is also directed towards the more scientific members within the forum.

My understanding of the work of silica gel is to aborb moisture, and once it is exposed to the atmosphere, it soon does it's job and is more or less useless, unless and until it is re-activated by heating the sachets in an oven to dispel all the moisure from the gel crystals. I have seen in my previous thread on lense fungus, that several members put in silica gel in their lens cases/pouches. To me this appears to be a waste of time, as the lens cases/pouches are NOT airtight and therefore the silica gel packets will quickly abosrb the moisture prevalent within these cases and become useless, and perhaps even be the cause of the "birth of fungus in lenses". My understanding of the use of silica gel is when it is kept inside air tight jars with whatever equipment that is placed within these jars. Therefore to put in silica gel packets in camera cases, does not do anything to prevent the growth of fungus. So could any of our science minded members explain what use is putting silica gel inside the camera cases/pouches.

Nathaniel

[sacha35]

Re: Fungus on lenses and Silica gel

I have stared this thread as it is specific to the effect of silica gel in preventing fungus/mould attacks. It is also directed towards the more scientific members within the forum.

My understanding of the work of silica gel is to aborb moisture, and once it is exposed to the atmosphere, it soon does it's job and is more or less useless, unless and until it is re-activated by heating the sachets in an oven to dispel all the moisure from the gel crystals. I have seen in my previous thread on lense fungus, that several members put in silica gel in their lens cases/pouches. To me this appears to be a waste of time, as the lens cases/pouches are NOT airtight and therefore the silica gel packets will quickly abosrb the moisture prevalent within these cases and become useless, and perhaps even be the cause of the "birth of fungus in lenses". My understanding of the use of silica gel is when it is kept inside air tight jars with whatever equipment that is placed within these jars. Therefore to put in silica gel packets in camera cases, does not do anything to prevent the growth of fungus. So could any of our science minded members explain what use is putting silica gel inside the camera cases/pouches.

Nathaniel

Cannot really help sorry, this is one of the biggest problems in camera equipment. I did find this bit of info though that is quite helpful.

http://www.chem.helsinki.fi/~toomas/photo/fungus/

[Nathaniel]

Re: Fungus on lenses and Silica gel

Sacha, Thanks for the info. I fully agree with the info you provided. Silica gel works only when kept inside an AIR TIGHT container- something which I did when I worked in Nigeria. I used large airtight glass jars to keep my lenses and slides. But I find that using silica gel in lens cases/pouches in UK is a waste of time, as the sachets have already absorbed moisture from the air. I stand to be corrected if any forum members thought otherwise.

[X-ray-spex]

Re: Fungus on lenses and Silica gel

When you buy any electrical equipment, there is always silica gel in the box and alot of them are not airtight, so why do they do it? As previously mentioned, it can't do any harm .........

[rajjayaraj]

Re: Fungus on lenses and Silica gel

Does size of the silica gel matters i.e the large surface area the better?

[sacha35]

Re: Fungus on lenses and Silica gel

Silica gel is only efficient if it is contained within is air tight, think of double-glazing, silica gel between the glass units sealed with mastic sealant to stop any air entering between the two pieces of glass.

Silica gel does what it is does, that is to withdraw moisture from the air, as Nathaniel Ramanaden has said if we can keep our kit in airtight containers with a silica gel sachet then this should eliminate moisture and help in the aid of preventing fungus/mould attacks.

The problem we have is dew point; more can be looked on the subject below.

http://en.wikipedia.org/wiki/Dew_point

[MX5]

Re: Fungus on lenses and Silica gel

Silica Gel is hydroscopic ... meaning it will drag water molecules from the air (to some extent). But will work regardless of any airtight container. An airtight (or indeed waterproof) bag/container will help by stopping excess moisture in high humidity environments reaching equipment. So fresh Silica Gel will do no harm in your camera bag. There are far better substances ... but nothing as cheap, safe and convenient as Silica gel. When I was a surface chemist we got to see some amazing things in this area.

Btw - most decent Cat Litter does the same job ! But make sure its unused !!

Btw - Milton is a neat way to combat mould / fungus. But I'm not sure I would try it on optics and even less sure I'd try it on L class optics!!!

[ruddles]

Re: Fungus on lenses and Silica gel

http://www.chem.helsinki.fi/~toomas/photo/fungus/

[ruddles]

Re: Fungus on lenses and Silica gel

Speaking as an expert of the best part of four months, I just leave my lens permanently attached to the camera and leave it on a shelf indoors, it has never been off the camera so I assumed that was the best way to avoid dust etc. But from what that article say's its the zooming in and out of the lens that sucks moisture in.....

If that is the case, I wonder, if when you have the camera up to your face adjusting the focus etc, whether your breath ( which will contain moisture and other crap) gets sucked iniside????

Might there be a value in wearing say a moisture/hepa face mask when focusing, or even a gas mask, or even an old brass diving helmet with a breather vent pipe....

How about wearing a light tent on your head and just have the front of the lens poking out...

Seriously I think simple measures that could limit the amount of moisture gaining entry via focusing is a worthwhile think-through...

[X-ray-spex]

Re: Fungus on lenses and Silica gel

Stick a few SG sachets in yer bag and be done with it ................... has anyone on here ever had fungus? I doubt it !!!

[Nathaniel]

Re: Fungus on lenses and Silica gel

I cannot think of anyone who has had fungus on their lenses, even though some members have left their unused lenses and cameras in the loft and nothing has happened to them. I was a bit alarmed and quite upset esp when I keep my equipment carefully in my spare wardrobe and never had any trouble with fungus and then to find that I am told that there was fungus on my lens!!!!!!!!!!

It would be a help to hear what other more experienced members have to say- Colin, Les,Trev, Jim ........... to mention a few.

[Woolley]

Re: Fungus on lenses and Silica gel

has anyone on here ever had fungus? I doubt it !!!

I have. Not on the lens, mind, and the tablets soon cleared it up.

[George Bear]

Re: Fungus on lenses and Silica gel

I've known it happen to friends twice. Once on a very expensive German lens which was cleaned for free even though it was a few years old. The other was a cheap Russian lens.

Although another friend did tell me they had trouble with a TTH lens back in WWII with growths. But it had seen action in the far east.

[colin C]

Re: Fungus on lenses and Silica gel

There are fungal spores everywhere and their preference is for warm damp atmospheres and still air. It is not possible to get rid of the spores, so our only option is to restrict the conditions that are ideal for their growth:

• My big lenses are kept in the open with a body attached.

• Smaller lenses and equipment are kept in a camera bag with 4 or 5 satchets of silica gel dessicant - the stuff that goes pink when it needs refreshing. I do know that ideally it needs an airtight container, but hell - it's better than nothing!

• I allow for air movement. The cupboard where they live has no doors and the room where they live always has the doors open. With normal movement, ventilation, convection and SWMBO flapping around the house, there is plenty of air movement.

• Luck plays a part. I have known very few people to get fungal growths on a lens and generally, there is no obvious reason. One lens got attacked, but it was always next to another lens that didn't. Figure that one out?

It is such a rare event in our climate that we shouldn't get over stressed about it. We have over three thousand members on this forum, each with multiple lenses and I would guess that probably two lenses in total are contaminated, the owners don't know and can't even see the fungus and it makes not a jot of difference to their pictures.

If I lived in the tropics, I might be a little more concerned, but only marginally.

Colin

[Nathaniel]

Re: Fungus on lenses and Silica gel

Thanks Colin for that full explanation. The one thing which is a bit puzzling is how long does it take for the silica gel to turn colour when it is kept in the camera bag. I would have thought as camera bags are not airtight, the SC will turn colour very very quickly, whilst inside the bag and then it ,the moist SC would encourage moisture to be present in the bag itself. I might be wrong here as I have not used SG in UK but only in Nigeria, where I kept my equipment and slides in airtight, large glass vaccum jars. The SC kept it's colour until I opened the jar to take my equipment out.

I am NOT over stressed about this matter but perhaps I have been caught on the wrong foot by this matter.