Conditioning Silica Gel (not exactly tortoiseshell conservation, but close)

Since I work a lot on tortoiseshell objects d’art, and in due course must make some of my artificial tortoiseshell, I have to deal with the fact that both true sea turtle shell and my vaguely pseudomorphic replica are both polymerized proteins (keratin or its counterfeit) and thus hygroscopic. Moving moisture into and out of the tortoiseshell scutes or the newly fabricated tordonshell is simply part of the equation.  To address these concerns is the reason I keep a couple hundred pounds of silica gel in the barn, taking what I need from storage and conditioning it, then using it.  For the most part I need desiccated silica gel to pull moisture out of the newly minted replica material.


Over the years I have adopted the following stoopid simple and cheep technique to acquire a sizable quantity of the desiccant needed.  Silica gel can be conditioned to almost any specific moisture content by simply placing it in the relative humidity atmosphere desired, then allowing it to acclimate.  Since what I want mostly is silica gel with a moisture content as close to zero as it practicable, I rely on simple techniques.


First I fill a clean slow cooking pot with silica gel and turn it on the highest temperature setting to cook off any bound moisture.  (Between making tordonshell and processing beeswax I am using slow cookers a lot, and purchase them at yard sales and thrift stores.)  I generally cover about 3/4 of the pot opening with a scrap of plywood to conserve heat and to allow the offgassing of the water vapor.  It takes about ten hours to get it as dry as it is going to get, which at this altitude during the dead of winter is about 3-5%.

Once the gel is conditioned it goes directly into a Gamma dog food container which with its seal-able huge opening makes a darned near perfect desiccation chamber.  When I use it long enough to pull out moisture to the point where the gel is too moist, I just cook it in the pot again.  It can be reconditioned repeatedly.

I’ll be using this chamber a fair bit in the immediate future as I need to make some tordonshell within the week.