Conditioning Silica Gel

One of the very useful tools for me is a desiccation chamber for drying out wet things, like uncured tordonshell, a fresh plaster casting, wet wood, or something similar.  I achieve such a chamber by using either a Gamma pet food container or a five-gallon pail with a Gamma retrofit sealing lid.  I load the chamber with desiccated silica gel and it is ready to do its work.  Put something damp in there, tighten down the lid, and the moisture gets sucked out of whatever it is you are trying to dry.

But the silica gel eventually gets damp itself, or at least adsorbs all the water being removed from the object in question.  Fortunately silica get can be re-conditioned an unlimited number of times.  My regimen for drying it out fully involves one of two routes typically.  For much of the year I simply place a mass of the crystals into a slow-cooker and turn it up.  In about 12-24 hours of cooking there the gel achieves a moisture content such that a sealed container holding it after cooling is at about 2-3% RH.

Another option for me in the winter is that I can dry out the gel in pans on top of kerosene heater I sometimes use to jump start the heat in the morning, or leave it on when the temperature is chilly but not yet frigid.  I keep a plate of aluminum on top of the heater to increase the heating efficiency by integrating a large radiant plate, and this often serves as a tray for heating things in the winter.  As with the slow cooker the total cooking time is somewhere between 12-24 hours, with the same 2-3% RH end point.

In either case, the slow cooker or the kerosene heater, I cover the batch overnight when I turn off the heat source, to prevent it from adsorbing moisture from the night air.

Silica gel can also be conditioned to a specific RH buffer but that is another topic.