It's time to put this myth to rest. Using rice to help dry batteries or a mod that got wet doesn't help at all. In fact, it slows down evaporation of any water that is inside.
I set up a 24 hour test using paper towel sheets with enough water added to bring their weight to 18 gms. I then put these wet folded paper towels in four places; a slightly ventilated box in rice, a slightly ventilated box 3 feet in front of a fan on low, a bare folded paper towel in still air, and a bare folded paper towel 3 feet in front of a fan on low. The complete results are in the table but two are presented here...
Five times more water evaporated from the box that was in front of the fan. It's clear that burying anything in rice just slows down the evaporation of any water that's present. This makes sense though. Rice can't vacuum up water. It can only absorb any water that evaporates and touches the surface of the rice. Even then though rice is a lousy absorber of atmospheric water.
- Amount of water that evaporated from the box in the rice after 24 hours = 2 gms
- Amount of water that evaporated from the box in front of the fan after 24 hours = 10 gms
Since the device that is wet is buried in rice, with no air movement, the humidity level quicky rises up to 100% next to any water that is present inside the device. This significantly slows down any evaporation that could take place.
Adding air movement blows away the layer of very humid air above any water, allowing the water to evaporate much faster.
Some of you might have tried using rice and found that you could turn on your mod a day or two later and it worked. But did you open up your mod to see if the water had actually evaporated? How can we know that the rice did anything?
Bottom Line: If you have a mod that got wet, do not turn it on. Remove the batteries (if possible), shake out any water you can, and then place it in front of a fan. Rotate it every couple of hours to try to get any blowing air into any seams or ventilation holes. It should be pretty dry internally in 24 hours.
Please don't bury it in rice!
 I'm sure there will be those who feel this test was invalid for one reason or another. It's backed up by every good test like this I found online but I strongly encourage anyone who feels I erred to do their own tests. I would love to see the results!
 For those who are concerned that the paper towels "lock in" the water, keeping it from evaporating:
Pictures of the setups:
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