Quote:
Originally Posted by allan gould
We used silica gel all the time in the lab and used a vacuum oven at 140 C for several hours or 30 sec bursts in a microwave and rest for 30 secs in between until turns blue, about 5 bursts ( had a colour indicator in it).
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The blue silica gel is now out of date because it is considered unsafe. The indicator was CoCl2. The cobalt is toxic and the stuff did tend to power up. Newer silica is orange when dry and clear(ish) when wet and the beads don't tend to turn to powder.