Once a silica gel packet is saturated with water, it can be “recharged” by placing in an oven at 120° C (250° F) for two hours. Microwaving silica gel is a very bad idea because there is a danger of burning one’s self when handling.
There is also a remote chance the beads can become superheated and may explode if rapid cooling takes place. In addition, microwaving a silica packet can result in an unpleasant smell. Heating above 300° C (570° F) can cause it to lose its hygroscopic properties. With a melting point of 1600° C (2900° F), it is very difficult to melt.
Some silica gel packets use an indicator dye that changes color when the packet is saturated with water. These dyes are made from cobalt chloride CoCl2 or ammonium tetrachlorocobaltate(II) (NH4)2CoCl4 and will cause a normally blue gel packet to turn pink when saturated with water. These dyes are temperature sensitive and will cease to be effective if the gel is heated above the 125-150° C (255-300° F) range.
This site was originally created as a Coppermine Gallery by Jason Champion who also scanned and photographed most silica gel packets. His tagline “Because silica gel packets are totally awesome” is my own view as well!
I have some Korean/English Silica Gel Packets I would love to show you.
I can email the pictures if you want… thanks