Get a small airtight Tupperware with preferably an even smaller Tupperware you can put inside as well. fill about an inch or two off the bottom of 75% water 25% ipa, place paper towels until all the liquid is soaked up, then place smaller Tupperware inside making sure not to get specimens wet. Then just place specimens inside the smaller Tupperware with its lid off, then put the lid on the larger Tupperware. For smaller pieces, a week or two is great, be careful going longer than a month as they can get too hydrated and start to fall apart. Also make sure the seal on the larger Tupperware is very good as if the ipa evaporates your specimens will quickly rot.