After your Sunday dinner, just put them in the oven for a few hrs. That will 'reconstitute' them. I have a shoebox full from 'K-Mart' shoe dept. Or next time you go past a copier/computer shop, ask them. The new units come packed with 1/4 lb? bags of silicagel. Great for hanging in the top of the tube or in your E/Pc box.
L.
ps. not sure re; life, but think indefinite?