I feel like there is some work to do on what people mean by ‘a dessicant’ - yes, I know dictionaries exist, but the purpose of dessicants in contexts such as shipment of electronics or storage of seeds is to uptake moisture from the air inside a sealed package, and usually, to perform that function fairly gradually over a long term.
Surely the objective for drying an item of wet electronics is to remove the water as fast as possible, and as completely as possible. Surrounding it with something that is excellent at absorbing moisture from the air, but only slowly, is going to hinder the drying process compared to, say, passing a stream of warm, relatively dry air across it.
In other words (I am ignoring wicking for now because it’s only effective for surface drying in this context), if the water has to exit via evaporation, which way is likely to be quickest?:
evaporation, then diffusion through calm air, which is being passively dried by a nearby dessicant
evaporation, then fast removal into a stream of constantly-refreshed, flowing air
I think there is some sort of unspoken notion that dessicants act like magnets and somehow ‘pull’ moisture at a distance. They can only do that by creating a humidity gradient, which seems a pretty weak effect.
You still have to think about it. Even assuming recently baked rice in a closed container keeps the overall container humidity much lower than room air, what really matters is the localized humidity near to and inside all those crevices in the electronic device.
A static environment inside a closed container is going to have trouble quickly whisking away the localized humidity - no matter how dry the overall container air is, it still has to rely on air currents to diffuse the moisture out of the phone.
A simple desk fan blowing regular room air on the phone is going to do a much better job stripping away all of the localized humidity inside crevices- as moisture is pulled from the phone, the moist air is immediately replaced by more dry makeup air, rather than have to slowly diffuse out.
Exactly so. That might not hold true in incredibly high humidity or something, I guess, where the fan would just be bringing in new, but already-moist air, but under normal conditions, the rice is just in the way of the water escaping.
That’s not quite true. Moisture is self-equalizing without induced airflow due to the properties of vapor pressure. That doesn’t mean having airflow won’t help, but it’s not really a static environment when you put something wet in it. It’s the same if you get out of the pool in a humid climate versus a dry climate. You dry off quicker in the dry climate even if there’s no wind in each situation.
Last year I was photographing a bike race all day in the rain, and my second camera got wet enough that all the buttons stopped working except the power and shutter button for the last couple hours. So I could still take photos, but not review them or change any settings. Because of the rain and mild temperatures my apartment was also quite humid. So to resurrect the camera for the next day, I had a low heater blowing on it all night at about 100°F while I ran the air conditioner as much as possible to also dry out the room air. Fortunately it worked by the next morning. No way did I have enough rice to completely submerge a whole DSLR camera.
by the way, tangentially, the solution to your problem is alcohol.
I’ve saved a couple of devices (one just yesterday) by shaking the water out then running as pure as possible alcohol through it. The alcohol washes the water (and dissolved solutes) away; isn’t likely to damage the device through rust or shorting electronics; and evaporates much faster and easier than water.
“Mangetout: I feel like there is some work to do on what people mean by ‘a dessicant’ - yes, I know dictionaries exist, but the purpose of dessicants in contexts such as shipment of electronics or storage of seeds is to uptake moisture from the air inside a sealed package, and usually, to perform that function fairly gradually over a long term.”
The same desiccant can work extremely quickly. At work we had air driers that used large desiccant tanks (2’ dia and 8’ tall) to dry the compressed air supplied to the building. The air flowed through one tank until the desiccant was full and the moisture level of the exit air began to rise at which point the controls switched tanks. The wet desiccant was then dried by heaters.
This was very high volume air - 150 psi in a 3" line at full throttle.
Not entirely on point but this thread reminds me of an old Batman comic. I used to read my uncle’s comics when we visited in the early 1950s so the comic may have been from the late 1940s.
Batman and Robin were trapped in a circular silo of some sort. There were bags of rice piled against the wall. And a hose. Batman laid a line of bags (looked like 100 pounders) from one wall across the floor to the doors. I remember it being about 15 feet. Then he soaked the bags of rice with the hose and within a short time the expanding rice blew the door open!
Not correct on several levels. First of all rice does not absorb much water at room temperature. I have cooked rice hundreds of times and if you use the “cook later” option and check the rice few hours later before it heats up, nothing has changed It’s still water on top of rice, not swollen rice. And how Batman got the bags to swell only in one direction with enough force to spring a pair of large industrial doors without bursting the bags in general - well, he’s Batman.
It can take days for rice to absorb water until reaching the same hydration as cooked rice. It’s just slow. Desiccants like silica gel will absorb water way way faster than that. But people don’t have bags of silica gel sitting around (unless they have a cat and then they might), but they do have rice. And rice, unlike silica gel, is not a skin and eye irritant and not harmful to eat. So if people are going to be given advice on how to dry out a phone then telling them to use rice as a desiccant is unlikely to be harmful even if it doesn’t work. So I guess we can say that rice is a very safe desiccant.
mixdenny: “The same desiccant can work extremely quickly. At work we had air driers that used large desiccant tanks (2’ dia and 8’ tall) to dry the compressed air supplied to the building. The air flowed through one tank until the desiccant was full and the moisture level of the exit air began to rise at which point the controls switched tanks. The wet desiccant was then dried by heaters.”
I feel like that’s such a very different setup from anything being described here that it really bears little relevance to the topic - it seems to me like that was ‘quick’ because the apparatus was scaled to make it quick
