Mould and mildew

<p>I recently went to retrieve a lens I haven't used in awhile, a 135mm ƒ/4 Tele-Elmar. I was shocked to find that the small chamois stored with the lens in a leather, velvet-lined Leitz case was damp with mildew and black spots. The chamois must have been wet when I put the lens away. The glass looks fine but, of course, there's a film on the barrel. I wiped that off with a soft cloth. The lens and the case smell of mildew. I was always taught that you put mildewed items in direct sunlight to bake out the mildew. I was wondering if there's anything else I should do for the lens and the case. In 60-plus years of storing my equipment, this has never happened. </p>

<p>....As for storage do not store in leather or cloth cases. Store in climate controlled area with dessicant packs.</p>

<p>Para moth flakes can kill mildew. You could put the case in a dark plastic bag with a handful, and leave it in the sun for days to heat and vaporize the mildew. But it will stink of them for years.<br>

Of course, don't do that to the lens!<br>

(That approach works well on old magazines that are mildewed.)</p>

<p><em>Store in climate controlled area with dessicant packs.</em><br>

Absolutely. I find Ziploc bags really useful. For cleaning anything other than glass which has got mold on it, I use so-called multi-surface cleaner, usually sold as being suitable for cleaning computer screens and casings - often comes in a kit with a microporous cloth.</p>

<p>You aren't alone in getting a rude shock. You need to know what the relative humidity in your storage is. They make cheap electronic RH & T devices.<br>

If it is well above 50%, it's too moist for your glassware. Your chamois probably wasn't wet when you put it in, but is hygroscopic, absorbed moisture, & helped to keep RH high in storage.<br>

UV light in sunlight kills off mould, but mould inside a modern lens doesn't get any UV; the sunlight merely warms up the lens and expels moisture.<br>

Silica gel is a bit useless unless you are prepared to recharge it periodically at 140 centigrade/celsius I think. I wouldn't use calcium chloride to dry a lens, as you might get airborne salts, but I don't really understand if this can happen.<br>

If it hasn't happened to you before, and you can get things optically clean, then just make sure you are storing lenses safe; not near an outside wall and not near the floor. If it's got internal bloom after drying, get it cleaned professionally.<br>

I like leather cases to carry lenses, but not for long term storage. It's a great lens.</p>

<p>This came to me as I was reading everyone's comments. (Sorry to hear of your bad luck Karl) Would anyone have an opinion about using the commercially available food storage systems? I mean the ones that vacuum out all the air, and seal a plastic bag or rigid container.</p>

<p>I purchased a bottle of that multi-surface cleaner used for computers and other electronic gadgets. I wiped the lens barrel with it. I placed the affected small leather pouches in my garden window, which gets direct sunlight in the morning, to bake them. I then bought a bulk bag of desiccant packets. I'm going to reëvaluate my storage practices in light of this experience. I've been storing my gear the same way for 60 years, but only now had a nasty surprise—weird.</p>