As part of a discussion on the M2 forums about using rice to dehumidify 3D printer filament, I replaced the 500 g bag of silica gel in the basement safe with a bowl containing 200 g of long-grain brown rice from our rice supply and let it sit for a while:
The abrupt drop in humidity from 52% to the logger’s minimum 15% marks the point where I replaced the rice with a fresh bag of silica gel, with a door opening shortly thereafter. The basement air outside the safe varied between 52% and 54% during that time, so the air inside the safe trended upward toward that goal.
The rice still weighed exactly 200 g after its stay in the safe, so we can conclude it hadn’t absorbed or released any water.
Conclusion: nope, rice doesn’t work as a dehumidifier…