I have three reusable desiccant solutions that I use. I avoid plastic packaging because it tends to melt easily in a microwave or oven.
* These 40g metal canisters are what Pelican sells for their cases. The metal case makes them very tough. The little clear window makes it easy to asses their condition. They usually recharge in about an hour and a half in a toaster oven at 350. The downside is that you can't dry them fast in a microwave oven. The 40g size fits nicely in a Questar case. Amazon sells them from multiple sources and sizes. https://www.amazon.com/Hydrosorbent®-Dehumidifiers-Canisters-Desiccant-Dehumidifying/dp/B005V2B29A/
* An old 35 mm film canister will fit snugly in a 1.25" eyepiece focuser. Drill some small holes in the bottom of an old 35mm camera film canister and fill the canister with the little desiccant packets. If you have had the Q interior exposed switching eyepieces or cameras in very damp conditions. Put it away with one of these in place instead of the eyepiece and you can be sure to have nice dry air inside the Q. Look for packets in paper packaging (I've found them in bulk on Amazon). Most are plastic that will melt in the microwave. The paper ones can be dried in a microwave within a few minutes. If you go longer than 30 to 60" at a time they may scorch. The packets puff up with the hot humid air. Although you can't see the desiccant, if you push them down and they don't inflate then most of the moisture is out. Make sure your canister holes are smaller than the desiccant particles in case a bag tears.
* An inexpensive solution is to get desiccant in bulk unpackaged. I also bought an inexpensive set of small, about 3x5" drawstring canvas bags. I label the bags with a Sharpie - "Desiccant/Poison". Half fill the bags with bulk desiccant and then securely double tie the bags closed. These can be quickly dried in a microwave as well. The burlap has less resistance to steam so they don't inflate the way paper bags do. When you check them while drying them out they feel noticeably moist until they are dry. A few minutes in the microwave will do it in bursts of no longer than 60". The desiccant can get quite hot and a fire isn't out of the realm of possibility. Letting them rest a minute or two with the microwave door open while moisture continues to escape and the desiccant cools down a bit between short heating sessions works reliably for me.
It looks like the plastic boxes you mentioned above are somewhat heat resistant, but the recommended oven temps are lower than those for the metal boxes and the drying times are longer.
An orange colored silica gel which is less toxic than the blue gel is available and might be a good choice. I think it is your only choice in the EU.
Edited by RobertPettengill, 22 July 2019 - 07:24 AM.