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Monthly Science: New Silica Gel in the Basement Safe

The humidity in the basement safe started rising this month:

Basement Safe - 2013-07-28

Basement Safe – 2013-07-28

The bag of new silica gel weighed 575 g, so it adsorbed about 67 g of water as the humidity rose from bone dry to 24%. Last month it had soaked up 31 g, so the safe admits nearly an ounce of water each month with 50% RH in the basement. It takes five months to accumulate 60-ish g of water during the winter.

According to the Sorbent Systems charts, silica gel’s equilibrium capacity at 24% is about 12% of the gel’s weight, which would work out to 60 g. That’s close enough, methinks, given the graph resolution; the humidity changes slowly enough that it’s sorta-kinda equilibrated in there… 67 g works out to 13.4% of the dry weight, which is in the same ballpark.

I made up three more bags of dry gel (500 g + 7 or 8 g tare), tossed one in the safe, one in the 6 gallon plastic bucket of 3D printer filament, and one in an empty 6 gallon bucket for comparison. Some 6 dot (10-through-60%) humidity indicator cards are on their way, seeing as how I don’t have nearly enough dataloggers to keep up with the demand…

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  1. #1 by Jim R on 2013-08-02 - 17:38

    Is this without the masking tape seal around the door?

    I keep wondering about getting a custom refrigerator door gasket to seal around the door. I thought RepairClinic would build to your measurements if the factory part was no longer available, but I don’t see that now. There is another place which will make custom gaskets. I don’t know anything about them, but here is a link to a page listing the various profiles:
    http://www.coldsupply.com/Custom-Door-Gaskets_c_64.html

    You can be the guinea pig until I get my safe…

    • #2 by Ed on 2013-08-02 - 19:25

      masking tape seal around the door

      It’s there, but somewhat sketchy…

      I should squash clay behind the door rim to measure the clearance, then install foam tape to exactly fill the crack: it’s on the to-do list!

  1. Basement Safe: Foam Door Seal | The Smell of Molten Projects in the Morning
  2. Monthly Science: Basement Safe Silica Gel Equilibria | The Smell of Molten Projects in the Morning