I have several plastic containers I use to hold flashlight parts. To keep the parts from rusting, I wanted to keep some silica gel in the containers to keep humidity down. At first I would get the ones included with shoes or pills, but then decided to just order some bigger 10 gram packages online. I numbered each of 10 pouches and put one in each of maybe 7 containers with a few left over. One of the leftover pouches I left out on my desk. The other two I kept in their original heavy duty ziplock envelope and put that in one of the plastic containers. I figured after a year, I could weigh the 10-gram pouches on my digital scale and see how well they were working, and maybe recharge them by baking them in an oven.
This weekend it had been a year. Most of the pouches now weighed about 13 grams, so they had absorbed about 30% of their weight in water. The ones in the envelope were around 12 grams, so they still picked up humidity. The one that was left out all year was also about 13 grams. So I think 30% is the maximum they can effectively absorb. I put the pouches in the oven for a couple of hours at 220 degrees and they all returned down to or just below their original weights, so the baking really worked and the pouches should be good as new (also they did not catch on fire or melt!). I probably need to weigh the pouches again every few months to see how long it takes them to get up to 13 grams when they essentially stop working. So I will use this entry to track results in the future.
I’m forwarding this to Thomas at work. He uses Silica Gel for storing video and camera equipment. And for camping. You guys could form a S.G.U.G.
Very interesting! My approach was more rudimentary – I kept adding new gel silica packets to the same Pelican case (where I store my camera gear). Would be interested to find out their effective date – I suppose geography/season/avg humidity is relevant. Quicker to 13 grams over the spring/summer.
I went ahead and weighed a couple of packets just to see how things were going and was surprised that some were already 12-13 grams, particularly in the larger containers. So I went ahead and re-dried all the packets and whereas before I had a few left over, this time I put two packets in the bigger containers. It makes me think that the tiny packets included with shoes or medicine would be completely useless since the 10g packets are much larger and were about to lose potency in less than a month.
After doing this for a while, I think the 10 gram packets aren’t up to the task. The containers range from maybe a quart to a gallon and the less empty space there is, the better the packets work. Also, extra layers help, like if I put a one-quart container inside a one-gallon container. Even so, after a few months, the packets are usually at their maximum weight, so I wanted to order some 20 gram packets. 10 packets are only $7.99 shipped. But 10 30 gram packets are only $8.99 shipped, so why not triple the power instead of doubling it? So we’ll see how that works out.