In article ,
Jon Elson wrote:

The problem is most of the packs are heat-sealed together, so if you get it
hot enough for the water to be driven out, the packs come apart and the
dessicant material spills out. Usually, it is actually some kind of clay
than silica gel.

So I found out the hard way. :-(

I tried to do this in an ordinary electric oven. I was careful to set
the operating temperature to the heat that the pack label indicated
was correct for renewing the packs.

Unfortunately, what seems to have happened is that the temperature of
the tray on which I placed the packs, ended up significantly higher
than the air temperature in the oven (not surprising since a lot of
the heat is radiated from the heating coils). The plastic packets
melted wherever they touched the tray, on the lower of the two trays
in the oven.

I suspect that these sorts of packs would be better refreshed in a
forced-air convection oven, where the black-body temperature of the
surfaces doesn't rise above the air temperature by more than a bit.