Question: <I was wondering if anyone has heard of a product called Dri-Z-Air? The package states that it removes excess water. It is a white granular material that contains calcium chloride.> <I'd like to know if anyone has had any experience with this product, and if there are adverse side effects to lens coatings, etc.> <It's cheap...> Answer?: I happen to work as an analytical chemist for a company that owns a company that sells a similar product which they call DampRid (http://www.damprid.com/). The drying agent (white granular material) is almost certainly a low grade calcium chloride. It is a harmless salt sometimes used in packaged foods. (Northerners--you could also use calcium chloride sold for de-icing that you may have lying around.) It has an enormous capacity for water, probably hundreds of times that of silica gel. It will eventually turn into a liquid after sucking up a lot water, which you could probably regenerate at ~275°C (~530°F). I know of a similar situation that uses calcium chloride to maintain a constant relative humidity (RH) of ~29% @ 25°C (~77°F). I believe the same would be true if you used one of these products, so long as there was always some solid calcium chloride present and the 'container' was reasonably well closed. I searched back a few digests and read one which recommended 30-50% RH and one which said 35-50% RH was optimal for storage of your equipment. I would guess 29% RH would be acceptable, but perhaps we should consult other digest members. TWIMC: The temperature that I have for regenerating silica gel is ~150°C (~300°F). Sorry for the long post, but I thought that this might interest many digesters (that love their Nikon equipment, to make it Nikon related).
