You can "recharge" silical gel by baking in the oven at 120 C for a couple of hours. If you do, be careful to remove the casing before you do, unless it is heat safe.
I have a small collection of oven safe dessicant packs that I keep on hand for emergency drying electronics.
You are better off soaking the wet electronics in isopropyl alcohol then trying to dry them in a bag full of desiccant.
One of the things that kills wet electronics is the dried residue that is left behind, creating shorts. Alcohol will wash away the water and leave no residue after it dries.
If the device has ink or glue you'd like to try to preserve, deionized water will mostly work too.
One time I tried drying a water-soaked smartphone in alcohol, but the alcohol got under the LCD screen and made it look blotchy permanently. The phone still worked but I stopped using it.
I did this with a surface go. I managed to drive off the alcohol with a heating plate. It took a few attempts. I think I heated it to 80 C or maybe even 100 C on the last run. End result was clean, except for a small line, possibly cracked diffuser.
I ruined a Thinkpad display the same way in the past, so I went for broke.
Yeah, I've had the same issue; as far as I can tell it's not actually the LCD itself but the backlight and the diffuser that end up getting screwed up. If you're trying to save electronics, keep the isopropanol away from the screen.
At my work any electronics that have had a water bath or flux-added rework will get an ultrasonic alcohol bath and then a forced air drying run. Alcohol is just so damned good for so much.
A few companies do make ultrasonic cleaners that are designed for flammable solvents, but they aren't common.
The easiest option is to just fill a plastic food bag with solvent, throw your part in, seal it with a clip and float it in your ultrasonic bath. The bag contains the vapour for safety, and it's easy to switch between different solvents and solutions.
That is next generation sous vide. Just controlling temperature is ho-hum. Getting it to just the right ultrasonic vibration to "cross-modulate the adipose frequency" is next level.
Even more spicy is vapor phase cleaning... evaporate the solvent, condense on the part to be cleaned suspended above it. Very effective since the impurities are constantly distilled out.
I've used both EtOH and propan-2-ol (IPA) for decades in ultrasonic cleaners both at room temperature and heated (quite warm to feel but not boiling hot) and never had a problem with fire.
Typically not (though some have heaters you can apply) but they atomize the fluid pretty well. The tiniest spark (static electricity) and some bad luck and you have the lid shooting into the roof and then a fire. As with everything, if you know what you are doing, go ahead.
"You are better off soaking the wet electronics in isopropyl alcohol."
Where I am ethanol (EtOH-95%, H2O-5%) is much cheaper and much more readily available and works almost as well. If silica gel is not available, then a fan works well followed by a warm (not hot) oven baking. Make sure the alcohol has essentially all evaporated first.
Keep in mind that some components can be affected by both EtOH and propan-2-ol — component markings, coil doping resins can dissolve, etc. Both alcohols are also good at removing solder flux resins/residues. (Oh for the days when freon and freon mixtures were available, component damage never happened.)
Devices with power transformers pose special problems, best to dry with alcohol first (hoping enamel coatings on wire aren't softened), then bake in oven on warm heat for a long while, sometimes 24 hours or more is necessary. With transformers it's important that this is done as soon as possible after wetting.
Edit: as I'm reminded by nyanpasu64 keep both alcohols away from LCD screens (likely all screens). I had a netbook PC and put it in a carry bag with a bottle of EtOH and it leaked. The PC still worked but the screen suffered the same outcome.
That may be country specific, but at least where I live, ethanol is much more expensive than isopropyl alcohol (30€/l vs 10€/l) - mostly because of dues on ethanol.
Right, if you live where duty is applied to ethanol then it's expensive. In Australia, where I am ethanol is available as a denatured product. That is, it includes a very small amount (much less than 1%) of denatonium (aka Bitrex) which renders it undrinkable (it's the bitterest substance known). As such, excise tax is not levied.
Here, one liter bottles of denatured ethanol are available in every supermarket everywhere, and up to 20 liters available in hardware stores (at bulk rates it's even cheaper).
For comparison, here denatured ethanol costs about $5/l [in US dollars] versus isopropyl at between $25 and $30/l.
In the United States, if you buy "Denatured Alcohol" at a big box store, it will be a toxic brew of often 50-60% methanol as well as smaller amounts of MEK, MIBK, and even acetone in addition to the ethanol. However, you can order "Specially Denatured Alcohol (SDA)" from various chemical suppliers or even Amazon. "SDA 40B 200" will be 99.5% ethanol with 0.1% tert-butyl alcohol and 0.0005% denatonium benzoate. It's what I use for camp stove fuel since I refuse to carry methanol in my pack with food.
I had a recent adventure attempting to replenish my Food Grade 35% Hydrogen Peroxide.
Amazon wouldn't even ship the stuff here. I'm coming to realize that any truly potent or powerful substance is strictly off-limits in consumer spaces. Plenty of good reasons for that. But such things as pure isopropyl and pure H2O2 are so versatile and tantalizing to have on-hand, rather than household cleaners with proprietary formulas, as much dilution as possible, unique MSDS, and obnoxious fake fragrance.
I can walk down an entire aisle in the hardware store, chockablock with bottles of household cleaners, and they all amount to 2 or 3 active ingredients, endlessly remixed for credulous homemakers.
35% — that's wishful thinking where I am. I can get 3% in a supermarket and 6% in a pharmacy. I can get H2O2 stronger than 6% but it's a major undertaking, and one is treated with suspicion and or put onto registers—like 'what the fuck do you want that dangerous stuff for?'.
"I'm coming to realize that any truly potent or powerful substance is strictly off-limits in consumer spaces."
There's no doubt about this and it's a damn pain. Outside industrial settings, chemicals that really work are becoming very difficult to get. I accept that highly concentrated (say >50%) H2O2 is dangerous and not something I want or need, and fuel grade (>70%) needs special handling thus the need for controls, but concentrations of about 20% are useful for bleaching where sodium hypochlorite is unsuitable, etc. For example, 6% H2O2 often isn't strong enough to remove foxing from documents, books, etc. so having ready access to a more concentrated solution that I could dilute to suit would be very useful.
It wasn't always like this, I'm old enough to remember when I could get most chemicals I wanted with little effort. Unfortunately, both occupational health and safety and terrorism have put the kibosh on ready availability, controls and restrictions have screwed all of us legitimate users.
Of course, restrictions covering to whom chemicals are sold haven't detrimentally affected the chemical companies one iota, in fact I'd maintain they've benefited them. They've proteced companies from potential lawsuits when users misuse chemicals and they've provided endless possibilities for them to market nigh-on-useless products to naïve consumers like the household cleaners to which you have referred. I could give examples of how some common household products have become less potent over the years but it'd take a full blog to go into details.
There's another downside here too, the less consumers know about the chemicals they use the more unskilled they become at actual chemistry—even if taught chemistry, using products whose ingredients are unknown doesn't add to their understanding. That's also a matter that I've not time to elaborate about here except to say lack of knowledge about chemicals is one of the significant reasons why society is becoming overly chemical-phobic.
I understand the problem with purchasing EtOH in the US. Frankly, I consider adding MeOH, MEK, etc. to denature it as both dangerous and an archaic procedure. (Moreover, outside lab reagents, MeOH should never exist without denatonium, it's just too dangerous.)
Some people will drink EtOH whether it's denatured with MeOH, etc. or with the much safer denatonium. Why blind or kill these people when one doesn't need to? Sure, EtOH will likely get them anyway but why should the State be their executioner?
There's something awfully wrong with that I reckon.
Puritan wrath, a nice mixture of hatred of ones own ant-existance and hatred on others not participating the labour camp race to the bottom, thats why?
Typically I would dismiss this as a bit overwrought but I came back from overseas last week and promptly was forced to drive in Boston, an activity that both takes place in the heart of US puritanism and perfectly encapsulates something that is frustrating in a way that could only happen in a place where "it's shit, it's supposed to be shit, and if you don't like it, there's the door" is a core principle.
Alcohol would dry up faster, demineralised water will have more time to dissolve and redeposit particles. Though you have to be careful with alcohol as it can destroy some plastics
I do microwave. It's pretty easy to not burn, just undershoot it - 10 seconds, see how hot it is, another 10 seconds. Once it's blazing hot shake it back and forth to get the steam off. If it's the colored kind (white when good, pink/blue when full of water) it's easy to tell when it's good. Takes about 30 seconds all together - I recharge my dessicant packs before every use. Of course, people are welcome to spend hours doing the oven method if they want. I just don't personally see an advantage, unless you have an industrial amount of packs to recharge.
It's cobalt chloride—the same stuff that used to be used on those little weather indicators where a little man or woman would pop out to indicate whether it was going to be wet or dry. They usually had a spot of blotting paper about 2cm round soaked in it. Cobalt chloride is blue when dry and pink when damp.
All ionic cobalt salts are toxic so cobalt chloride is not used as an indicator in silica gell packaged for use with food. That said, it's an excellent indicator for telling whether your silica gell is still working or not.
Pure silica? It's really just SiO2. It might kind of fragment/ burst if it has a lot of water absorbed and you heat it too fast. Then everything in the vicinity would get sprinkled with fine dust which you shouldn't inhale in large quantities, as it might cause silicosis.
Cobalt chloride decomposes only at extremely high temperatures and it melts only at very high temperatures (726 °C), which could not be reached, in any case not before all water in the silica gel would be converted to steam and it would be eliminated. Even when no water is left, it is unlikely that the beads with cobalt chloride could absorb enough microwave energy to be heated at very high temperatures.
So by itself cobalt chloride could not cause any problem.
However, I have no idea whether the cobalt chloride is not mixed with some organic binder, to make it stick to the silica gel beads, which could burn in the oven, though that is also unlikely to happen before all water is removed from the gel, allowing an increase in temperature above the boiling temperature of water.
By using low microwave power and short time, so that no boiling of the contained water should be seen, it should be possible to dry even beads with cobalt chloride.
If the indicator is cobalt chloride, which is blue when dry and pale pink (possibly almost invisible) when wet, that can be toxic or carcinogenic when ingested in great quantities, or when you inspire a lot of dust of it, but it is not dangerous to handle when in compact form.
It is certainly not something like a poison, where small quantities can have harmful effects, at least not for most people.
Like nickel, cobalt can cause allergies in some people, in which case repeated exposure can have serious effects even in small quantities, in those humans who are sensitive to it.
They can also be died at much lower temperatures, it just takes a lot longer. I dry mine by leaving them on top of a computer at ~35C for a week, I believe the air flow from the fans is important.
The color indicating ones are useful so you can see when they are dry.
At what ambient humidity do you do this? Where I am we are having a dry day at 45% humidity today. Tomorrow it'll be over 90%, and it'll stay between 50% and 90% through the weekend. I would expect that you need a more consistently dry environment for this to work
Immediately take them out of the oven and store in the smallest airtight container you have. Obviously they'll absorb the humidity in the container and whatever is introduced anytime you open it. Ideally, keep them in containers that have an excellent seal and minimal internal volume like quality ESD bags.
I don't think I've ever seen an antistatic bag with a very good seal, and I'm not sure it's a good idea to drop something directly out of a hot oven into them either.
If they're not getting hydrated slowly, they're not serving any purpose. The whole point is that water goes into them instead of whatever you're trying to keep dry.
I think the grandparent comment meant keeping unhydrated during storage (for future uses of emergency drying electronics), not while it is being actively used for its intended purpose.
other people are suggesting the microwave rather than the oven. to my mind it seems very possible that you don't keep them from hydrating, you just dehydrate them on-demand.
When my last phone took an unsanctioned swim, my research suggested that a food dehydrator is a last resort. It risks forcing water vapour further into the electronics of the system, rather than encouraging it to move out.
I did find a clever solution online that tried to induce mechanical suction on your phone to force the vapour out, but it was too expensive for a one off use.
In the end I had to resort to the food dryer anyway, after the silica gel failed to work.
I've never used it for drying wet electronics. The couple of times I've dunked my phone, I've just let it air-dry for a couple of days and it's been good.
I use silca gel for storing 3D printing filament and long-term clothes storage.
You can "recharge" silical gel by baking in the oven at 120 C for a couple of hours. If you do, be careful to remove the casing before you do, unless it is heat safe.
I have a small collection of oven safe dessicant packs that I keep on hand for emergency drying electronics.