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Sunday, November 28, 2010

From 'Gilligan' at about 2 gram desiccants and regenerating.

Q. Been ordering from you for a few years now. I travel to the Philippines and use these packets in my underwater camera housing. Should they be kept in the refrigerator when not in use? The last batch started to turn pinkish while stored in the bag they came in after about 3 months. It is a very humid climate there.

(in response to many requests, packets are available at The Preservation Station)
A. Good Afternoon, Gilligan!
You should not keep the packets in a fridge. Conditions fluctuate in there with every opening and it can be very humid or very dry. Extremes are best avoided for desiccant storage.
If stored in a cool, dark place (like an fully interior closet or cabinet) the shelf life should be at least one year. Of course, that's in temperate conditions with stable humidity.

If this is not possible, then I recommend keeping the desiccant in a glass jar with as little airspace as is possible. It would still be best to store as temperately as is possible, even in the glass. When you take out a working amount keep the jar open for as short a time as is possible.

If you use small glass jars, you could divide the desiccant packs amongst 3 or 4 of them to further minimize exposure time. Baby food jars and little jars that caviar and pimentos come in come to mind. The lids of baby food jars are generally not meant to be opened and closed many times, so the others might be better. One can go along with you in your gear and the others will be undisturbed until needed.

Another idea you can try - I'll include some small barrier sleeves in this order that you can use them to double-bag your working quantity.

Thank you for the feedback.  As soon as I get a moment, I'll do a blog posting so the information is out there for other photographers.  I'm sure others have run into the same problem. Come to think of it, a dive site is pretty much by definition a hostile environment for desiccant!

Thanks for your fast reply. I did keep the unused ones in a glass jar with a seal type lid. I filled any empty space with paper towel but several small jars with as little empty space as possible may be better as you suggested. No baby food jars where I go in the Philippines :-)

Even though they are not the rechargeable type I have used a hairdryer on some of them to try to rejuvenate them. Any chance you would ever put the rechargeable desiccant in those little packets? I know a toaster oven or microwave is too hot for the wrapper but the hairdryer didn't seem to harm the wrapper? Maybe the hairdryer is not hot enough to recharge the desiccant?

I use a Canon G10 camera in a Canon housing. Many people use the Canon cameras as they are about the only company that makes a wide variety of cameras along with the housings. Their housings are very compact and leave little room for the desiccant packets but I manage to get three in mine. Fogging is a problem in these small housings so the desiccant is a must. I also hold my housing up to the A/C unit for about 10 seconds before I seal it up. One of the Filipino dive instructors who does not have A/C puts his in the fridge for about a minute or so then seals it up. It seems to help to get the humid air out of the housing before sealing it. It is also IMPERATIVE to keep these housings out of the sun or they will fog up after they get put in the water.

Nevertheless it still is a great product at a great price. I plug it on where a lot of underwater photographers hang out. My nick there is "Gilligan".

I was out of the shop yesterday - at home making oodles of mini fruitcakes for the holidays. They take 4 or more weeks to cure (with twice-weekly brushings of booze!) and so they have to be laid in right after Thanksgiving at the latest. Come to think of it, I don't think I have ever succeeded in getting them done earlier!

Thanks so much for all of the constructive information.  Will definitely do a post. Here's what we have found regarding recharging:

The gel is not recommended for recharging by the manufacturer.  The micro-perforated film is, however,  polypropylene, which has a fairly high melt point. With that in mind, I experimented with microwaving and found that it is possible to get the gel back to blue.  You can even use high power! The gel does not seem to be as efficient as when new and the packet gets a bit brittle. Still, it is possible to use them.  The gel does fracture at temps over 235° and that can allow very small bits to escape the substrate.  I need to work on a way to convey the possibility of regenerating (for at least one cycle) while cautioning about the possible dusting. Perhaps I can suggest that the regen packets be use only for other purposes.  Purposes where the possibility of micro-grains floating about could cause no harm? The gel could also be emptied, microwaved and then twisted in paper or Tyvek?
The Preservation Station