The big bags of that candy also come with an actual silicagel packet to keep humidity from ruining the candy, so it's always a fun game of "guess what's edible".
> Benford was brought in to help calculate the probability that someone or something would intrude on the site for as long as it remains dangerous — approximately the next 10,000 years. It turns out, few things (outside of organized religions and ritualized traditions) last that long.
What a weird thing to say. No organized religion or ritualized tradition has ever lasted that long.
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.
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.
"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 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.
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.
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.
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.
Not mentioned by the article: 99% of all silica gel packets are utilized cosmetically, with no practical effect.
Is your equipment shipped in non-airtight containers, like cardboard boxes? That silica gel will absorb all the water it can before it leaves the factory. It effectively does nothing after that.
Are your silica gel packets stored in non-airtight bags? In that case, they're spent before they enter the packagin at all.
Did you save a bunch of silica gel packets from stuff Amazon sent you, and use them to "dry out" your gym gear (I have known friends to do this). Those packets are long-since "full", and do nothing. (My friend: "Well, it can't hurt!" And it also can't help.)
They aren't cordless water pumps, moving humidity out of the air perpetually into their contents - but that's how most people view them.
Is this true? Are you suggesting that manufacturers are adding the packets for psychological reasons? Even if they are used up by the time a consumer sees them, are we sure they had no benefit at an earlier time?
“That single gram of silica gel could have an internal surface area of eight hundred square meters—the size of almost two basketball courts.“
Can someone help explain this? I’m having a hard time wrapping my head around this. The tiny packet has this much surface area due to how much space exists within the balls???
Former W.R. Grace employee: Molecular Sieve Desiccant Beads (also manufactured by W.R.Grace) are even more absorbent than regular silica gel. It's found in most double-pane windows inside the metal track between both panes; slowly absorbing any moisture over many years to keep them from fogging/going 'blind'.
You can use MS to dry flowers in record time... and use it to quickly heat up baby food in a pinch if needed... just put a smaller container of food in a bigger pod filled with MS and pour water of the MS... it's ultra-rapid absorption of water creates heat as a byproduct.
I'd just learned of (and shared a link to) a related technology, "getters", which similarly hold tight vacuums in various applications for years if necessary:
Those are used in vacuum-sealed windows and glazings (the topic of the post I was commenting to).
There are also moisture scavengers put into cooling applications (refrigerators and A/C) to remove any incidental water from refrigerant, which I suspect operate more like your MSDBs.
Getters can hold tight vacuums for several decades, even! I have many vacuum fluorescent displays from the 70s still working perfectly. As long as the getter spot is shiny and not white, it is holding vacuum fine.
The ones in food are often oxygen absorbers instead of dessicants. They contain iron "sand" that is, unfortunately, not reusable. They're usually very flat and have a "do not microwave" warning on them in addition to "do not eat".
(This is not to say dessicant packets aren't used in food, just that not all of those packets are dessicants)
Silica packets are definitely used in foods that need to be kept super-dry, like seaweed or nuts -- absorbing residual moisture that was in the product during packaging.
I've never heard of an oxygen absorber used in food. A lot of snacks and things (e.g. all potato chips) in airtight containers are packaged in nitrogen so there's no oxygen in the first place.
Are they for small-scale food production that can't use nitrogen? I've never encountered them in my life.
Aka orbees. Also useful as a soil amendment if you have clay soil, it stops it from claying so much and retains water underground for plants.
They make glow in the dark ones, which I put into a masonry jar with some distilled water and a drop of bleach, I light it from underneath with a USB LED and it glows for about an hour. Cool night time light.
Back in the early 90s they had a different name and they were irregularly shaped. This was for Soil Amendment. I think it started with a Z.
i don't think so. It was a brand name of whatever SAP they had decided was safe for plants to bathe in. I found some about a decade ago, just by asking about water retention crystals at an agricultural outlet. I think it's cheaper to buy orbees when they're on clearance, though.
I think it's more expensive, and I'm not sure it can absorb vapor (not liquid)
It's fun that it has the same refractive index as water, so if you put clear ones in water they disappear. Then you ask someone to put their had in a bowl with them for a surprise.
CNC Kitchen put out a great video on the practical use of silica gel. I especially found his exploration of different methods of drying to be of interest.
Yeah it's a bit of a weird way the article puts it. Measuring in square meters but then referencing basket ball courts which are almost nonexistent in Europe :). They should have used a football (but soccer, not the American kind) field. Though in that case I guess it will be a fairly small division of one too which makes it sound smaller than it is.
I honestly have no idea how big a basketball court is.
I'd love to say that my comment was some commentary on the weirdness of the units, but really, it just stuck out to me, and I thought it'd be funny if I treated "gridiron football field" as the imperial system equivalent unit to the metric "basketball court" unit.
I rarely make comments on HN that are mostly just humorous and not actually intending to be on-topic... but every once a year or so.
What do you mean they don't exist. I see them everywhere, indoor, outdoor, also every single school gym regardless of level is also a basketball court. I've lived in 3 countries here east & west Europe and this is valid across different places and cultures.
As a kid, I imagined silica gel was a special treat. It seemed like the ultimate ‘DO NOT EAT’ dare. I put one in my mouth, waiting for superpowers or disaster.
Turns out, it just tasted like disappointment and regret. 10/10 would not recommend, but at least I lived to tell the tale!
Five ads and seven "subscribe" buttons, for one short article about silica gel.
Wikipedia has a better article.[1]
> You can just microwave them too, on low power... Oven drying has the advantage that you can set the temperature so there's no risk of overheating anything.
It's hard to hurt silica gel itself with kitchen level heat. Melting point 1200C. The packet it comes in is more of a risk.
Although there are forms with other chemicals that change color when humid. Also, heating wet desiccant fast enough to produce steam might crack the material.
Silica is great for removing humidity from air. But what I want is to remove oxygen from air, so my food stays fresh longer. Any clean and easy to use substance/method for that purpose?
Yeah don't. Like many metals, finely dispersed iron can self-combust on air.
I'd suggest an air-tight packaging filled with CO2, or, if your food is susceptible to acid, N2, if at all feasible.
Industry uses additives similar to hydroquinone, mixed directly into, e.g., plastics. Plenty of them are food-safe, but I wouldn't know where to buy them if you aren't a business.
Tldr: those plastic bags that salads come in are WAY more interesting than you think. They're selectively permeable membranes that only allow certain gasses in/out.
I reuse ones I find in consumer goods by putting them into a jar, together with open superglue bottle(s), and putting the jar into fridge. Not a scientific study, but it does seem to keep the glue for longer then just fridge.
Isn't it also because the jar is closed that the superglue keeps for longer? A fridge also dehydrates the air (condenses on the back wall in most cases).
Maybe that would be enough. But the belt-and-braces approach of superglue with silica gel bags in a closed jar, in a fridge, seems to work well and has meant the superglue is still usable when I end up needing it....
Starting to put these in my hygroscopic fertilizers was a game changer. No more bricks of unusable waterlogged crap after a few years. You can regenerate the beads in the microwave and you can buy color-changing ones on Amazon that indicate their status.
Probably because they look like candy, and they're packaged with food a lot?
Even if not packaged with food, these sachects left on the table while unboxing, e.g. a pair of shoes, might entice kids... And it's just easier to print "DO NOT EAT" rather than have separate production lines for "for shoes" and "for food".
Although, from the description, it seems they're perfectly safe (because they're inert) to eat...
I realized this week for the first time exactly why. there was one in my instant ramen along with its other seasoning packets. If not paying attention you could easily be having your noodles with added desiccant flavor.
In small quantities. As somebody already pointed, your body likes to keep its water inside it, it also doesn't like when stuff carries large quantities of unmixed digestive fluids from one part of your body to another.
They are probably quite harmful if large pieces get eaten in non-small quantities. Or powder in large quantities that are not previously mixed with a liquid. But I don't know of anybody that tested that.
With millions and millions of those things around I’d guess quite a few get ingested accidentally and we don’t hear of them causing problems. It must be pretty safe (well as safe as eating a small amount of sand is).
It's a choking hazard that is sometimes included in food packaging so it's just to cover the manufacturer since they don't really know what products it may end up in. Silica gel is non-toxic although maybe could cause some issues if you deliberately ate a huge quantity of it.
I'm pretty sure it's just following the rules of the strictest food packaging laws among the places they expect them to end up. In some jurisdictions non-food that is directly inside a package along with food needs to be labeled that way. So they just do em all like that.
What a perfect opportunity to link to one of my favourite candies https://waskstudio.com/products/sealed-fate-candy-packets
Balls of hard candy shaped and packaged like silica gel!
Also a perfect opportunity to link to one of my favorite comics https://onegianthand.com/post/188730414621/silica-gel
The big bags of that candy also come with an actual silicagel packet to keep humidity from ruining the candy, so it's always a fun game of "guess what's edible".
What a perfect opportunity to link one of my favorite podcast episodes https://99percentinvisible.org/article/beyond-biohazard-dang...
Why danger symbols can’t last forever.
> Benford was brought in to help calculate the probability that someone or something would intrude on the site for as long as it remains dangerous — approximately the next 10,000 years. It turns out, few things (outside of organized religions and ritualized traditions) last that long.
What a weird thing to say. No organized religion or ritualized tradition has ever lasted that long.
Vsauce Michael approved! https://www.youtube.com/shorts/OEYqWMHyhtM
What a fun little website!
Every time I stumble onto it I have to resist not buying five gimmicky things.
My favorite is the Short Sided Ruler.
Perfect for April 1st.
Do they have candy that looks like Tide pods?
Got to ask why?
self explanatory, it's dessi-can instead of dessi-cant
Why not?
Why ask why? Try Bud Dry.
I'm earnestly surprised those are legal. Here's another idea, sweet fruit juice concentrate in a drain cleaner bottle. What could go wrong?
How about a cleaning chemical packaged to look like fruit juice? Fabulous.
Lolimsorandom/imsoedgy types have plenty of space to work in, without messing with child safety.
I didn't find this in the article, so:
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 think the protocol would generally be to disassemble the device and then clean with alcohol. Easier said than done with a phone of course.
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.
"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 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.
Right, I was being polite, my question was rhetorical.
it's cheaper and the free market is regulating itself as god intended.
Isn't the ethanol denatured? There's a duty on that as well?
It is, with denatonium hence no excise tax.
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.
I'd be very scared of IPA in an ultrasonic cleaner. Sounds like a recipe for a fire. Or is your machine perhaps designed for safe IPA cleaning?
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's a quite elegant solution I hadn't considered before.
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.
And someone is already doing it:
https://besservacuum.com/en/ultrasonic-food-treatment-machin...
I'm scrolling before coffee and initially took your acronym as India Pale Ale, which would certainly be a different cleaning experience...
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.
Do ultrasonic cleaners get hot?
I've run isopropyl alcohol in an ultrasonic cleaner.
It did get significantly hot after a while. And smelly, so it was surely aerosoling (is that a word?) somewhat.
I did it outdoors and away from anything that could catch fire because it felt rightly sketchy.
It's basically an industrial ultrasonic humidifier attached to the bottom of a buffet tray. And it does get warm.
A lot of ultrasonic cleaners have a heating element.
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.
I totally agree though my use of it is pretty different ;)
What percentage alcohol is used?
usually 99%
Why not demineralized water instead of alcohol?
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
You can just microwave them too, on low power. It's much, much faster and power efficient.
Also much harder to control. Oven drying has the advantage that you can set the temperature so there's no risk of overheating anything.
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.
FYI, but some desiccant coloring agents are cancerous
Yeah. Unless it's advertised as "food grade" and has a specific "Cobalt chloride free" I would def. not put it in food -
These fit the bill. Assuming they're not straight-up lying or anything...
https://www.amazon.com/Rechargeable-Desiccant-Dehumidifiers-...?
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.
Silica gel for industrial purposes sometimes is soaked in it as an indicator.
is there any harm in overheating silica when drying it out?
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.
Practical details about the types of desiccant beads and how to dry them.
https://www.youtube.com/watch?v=6tHInlFfMcM
Can someone speak authoritatively on how safe/unsafe it is to put the silica gel packets with cobalt chloride indicator into the oven?
(By default, I've been assuming it's not sufficiently safe.)
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.
There's silica gel you can buy without cobalt chloride that I use for storing my 3d print filament.
I also do this. I'm wondering whether anyone needs to be warned about cobalt chloride, or it's innocuous.
If you're concerned, the orange/green silica gel is non-toxic.
I use dessicants for 3D printing. I've heard you can dry them out safely by just microwaving them for a few seconds. I wonder if that's good enough.
You can get the ones with indicators, which change color according to how saturated they are.
You can check the color to see whether it's time to microwave them, and whether they are dry once you microwaved them.
The indicator is supposed to be toxic though. I’ve always seen warnings to never reuse that kind.
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.
I use them in my car against condensation.
The instructions on tge cover say 3 minutes at 700W in the microwave.
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
This sounds like a great idea, but how do you keep it from being "drained" or hydrated?
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.
Another option is a canning jar.
For the quantities of silica gel typically used, a smaller spice or condiments jar (glass with metal lid) would be more appropriate for most people.
Throw them in a container with some silica gel.
In a "ziplock" bag which you have vacuumed all the air out of.
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.
If you're keeping them on hand for drying electronics in emergencies then you need to store them somewhere airtight.
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.
I store mine in an plastic box with airtight lid designed for food storage.
Precisely this! Even so, I refresh them just before using them.
TIL about the microwaving trick. I'll have to find out more about it. My concern would be the gel beads popping from internal pressure.
I use a food dehydrator for this, but the principle is the same.
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.
Not mentioned by the article: 99% of all silica gel packets are utilized cosmetically, with no practical effect.
Is your equipment shipped in non-airtight containers, like cardboard boxes? That silica gel will absorb all the water it can before it leaves the factory. It effectively does nothing after that.
Are your silica gel packets stored in non-airtight bags? In that case, they're spent before they enter the packagin at all.
Did you save a bunch of silica gel packets from stuff Amazon sent you, and use them to "dry out" your gym gear (I have known friends to do this). Those packets are long-since "full", and do nothing. (My friend: "Well, it can't hurt!" And it also can't help.)
They aren't cordless water pumps, moving humidity out of the air perpetually into their contents - but that's how most people view them.
Is this true? Are you suggesting that manufacturers are adding the packets for psychological reasons? Even if they are used up by the time a consumer sees them, are we sure they had no benefit at an earlier time?
“That single gram of silica gel could have an internal surface area of eight hundred square meters—the size of almost two basketball courts.“
Can someone help explain this? I’m having a hard time wrapping my head around this. The tiny packet has this much surface area due to how much space exists within the balls???
Former W.R. Grace employee: Molecular Sieve Desiccant Beads (also manufactured by W.R.Grace) are even more absorbent than regular silica gel. It's found in most double-pane windows inside the metal track between both panes; slowly absorbing any moisture over many years to keep them from fogging/going 'blind'.
You can use MS to dry flowers in record time... and use it to quickly heat up baby food in a pinch if needed... just put a smaller container of food in a bigger pod filled with MS and pour water of the MS... it's ultra-rapid absorption of water creates heat as a byproduct.
I'd just learned of (and shared a link to) a related technology, "getters", which similarly hold tight vacuums in various applications for years if necessary:
<https://news.ycombinator.com/item?id=43498489>
Those are used in vacuum-sealed windows and glazings (the topic of the post I was commenting to).
There are also moisture scavengers put into cooling applications (refrigerators and A/C) to remove any incidental water from refrigerant, which I suspect operate more like your MSDBs.
Getters can hold tight vacuums for several decades, even! I have many vacuum fluorescent displays from the 70s still working perfectly. As long as the getter spot is shiny and not white, it is holding vacuum fine.
Ahhh. This explains why my glass panes go "bad" after 20-30 years in the harsh Montana conditions we have.
Clearly, you can just put the window in the microwave for a few seconds to refresh it ;-)
The ones in food are often oxygen absorbers instead of dessicants. They contain iron "sand" that is, unfortunately, not reusable. They're usually very flat and have a "do not microwave" warning on them in addition to "do not eat".
(This is not to say dessicant packets aren't used in food, just that not all of those packets are dessicants)
Can you point to an example?
Silica packets are definitely used in foods that need to be kept super-dry, like seaweed or nuts -- absorbing residual moisture that was in the product during packaging.
I've never heard of an oxygen absorber used in food. A lot of snacks and things (e.g. all potato chips) in airtight containers are packaged in nitrogen so there's no oxygen in the first place.
Are they for small-scale food production that can't use nitrogen? I've never encountered them in my life.
I've seen these in imported Asian products, especially from China and Japan. Biscuits and similar dry snacks.
I've never seen it for a European product.
The Gimme-brand seaweed snacks I get contain oxygen absorbers. So do packages of Tillamook Country Smoker jerky and meat sticks.
They seem to be fairly common with packages of jerky and other self-stable cured meats.
There are both. Oxygen absorbers are used for moist snacks, apparently.
Bacon bits, fried onions, beef jerky.
Another one of these fascinating super absorbent materials is SAP (Superabsorbent polymer).
It is heavily used in diapers, tissues, water retention for plants, etc. SAP can absorb liquid up to 30-60 times its own volume.
https://en.wikipedia.org/wiki/Superabsorbent_polymer
Aka orbees. Also useful as a soil amendment if you have clay soil, it stops it from claying so much and retains water underground for plants.
They make glow in the dark ones, which I put into a masonry jar with some distilled water and a drop of bleach, I light it from underneath with a USB LED and it glows for about an hour. Cool night time light.
Back in the early 90s they had a different name and they were irregularly shaped. This was for Soil Amendment. I think it started with a Z.
> I think it started with a Z.
zeolite? https://en.m.wikipedia.org/wiki/Zeolite
i don't think so. It was a brand name of whatever SAP they had decided was safe for plants to bathe in. I found some about a decade ago, just by asking about water retention crystals at an agricultural outlet. I think it's cheaper to buy orbees when they're on clearance, though.
I think it's more expensive, and I'm not sure it can absorb vapor (not liquid)
It's fun that it has the same refractive index as water, so if you put clear ones in water they disappear. Then you ask someone to put their had in a bowl with them for a surprise.
My kids loved that stuff when they were young.
CNC Kitchen put out a great video on the practical use of silica gel. I especially found his exploration of different methods of drying to be of interest.
https://www.youtube.com/watch?v=6tHInlFfMcM
"That single gram of silica gel could have an internal surface area of eight hundred square meters—the size of almost two basketball courts."
This reads like something from The Three Body Problem :)
> That single gram of silica gel could have an internal surface area of eight hundred square meters—the size of almost two basketball courts.
For us Americans, that's about 8600 square feet...and around a seventh of a football field.
Yeah it's a bit of a weird way the article puts it. Measuring in square meters but then referencing basket ball courts which are almost nonexistent in Europe :). They should have used a football (but soccer, not the American kind) field. Though in that case I guess it will be a fairly small division of one too which makes it sound smaller than it is.
I honestly have no idea how big a basketball court is.
I'd love to say that my comment was some commentary on the weirdness of the units, but really, it just stuck out to me, and I thought it'd be funny if I treated "gridiron football field" as the imperial system equivalent unit to the metric "basketball court" unit.
I rarely make comments on HN that are mostly just humorous and not actually intending to be on-topic... but every once a year or so.
I don't know where you are in Europe, but from my experience basketball is popular in France and courts are everywhere.
Soccer fields don't have a standard size, however, so you're not going to be able to give a true comparison.
What do you mean they don't exist. I see them everywhere, indoor, outdoor, also every single school gym regardless of level is also a basketball court. I've lived in 3 countries here east & west Europe and this is valid across different places and cultures.
As a kid, I imagined silica gel was a special treat. It seemed like the ultimate ‘DO NOT EAT’ dare. I put one in my mouth, waiting for superpowers or disaster.
Turns out, it just tasted like disappointment and regret. 10/10 would not recommend, but at least I lived to tell the tale!
Five ads and seven "subscribe" buttons, for one short article about silica gel.
Wikipedia has a better article.[1]
> You can just microwave them too, on low power... Oven drying has the advantage that you can set the temperature so there's no risk of overheating anything.
It's hard to hurt silica gel itself with kitchen level heat. Melting point 1200C. The packet it comes in is more of a risk. Although there are forms with other chemicals that change color when humid. Also, heating wet desiccant fast enough to produce steam might crack the material.
[1] https://en.wikipedia.org/wiki/Silica_gel
Ublock Origin defaulting to blocking all the Javascript by default and the only "ad" is the "get this newsletter" ad near the bottom.
This was fantastically well written. Big thank you to the author and the poster!
Silica is great for removing humidity from air. But what I want is to remove oxygen from air, so my food stays fresh longer. Any clean and easy to use substance/method for that purpose?
Oxygen absorbers. Little paper packets of iron powder.
Yeah don't. Like many metals, finely dispersed iron can self-combust on air. I'd suggest an air-tight packaging filled with CO2, or, if your food is susceptible to acid, N2, if at all feasible. Industry uses additives similar to hydroquinone, mixed directly into, e.g., plastics. Plenty of them are food-safe, but I wouldn't know where to buy them if you aren't a business.
You leave the iron powder in the packets. No need to disperse it, and certainly not in the air.
I think a lot of us might even confuse the two. The packets look fairly similar too.
Radiolab did an amazing episode on food freshness. They talk about plastic produce packaging, which is a bit of a modern marvel.
https://radiolab.org/podcast/forever-fresh
Tldr: those plastic bags that salads come in are WAY more interesting than you think. They're selectively permeable membranes that only allow certain gasses in/out.
Vacuum
I reuse ones I find in consumer goods by putting them into a jar, together with open superglue bottle(s), and putting the jar into fridge. Not a scientific study, but it does seem to keep the glue for longer then just fridge.
Isn't it also because the jar is closed that the superglue keeps for longer? A fridge also dehydrates the air (condenses on the back wall in most cases).
Maybe that would be enough. But the belt-and-braces approach of superglue with silica gel bags in a closed jar, in a fridge, seems to work well and has meant the superglue is still usable when I end up needing it....
https://onegianthand.com/post/188730414621/silica-gel
This is sold as crystal cat litter. Very useful to put a sock in the car, the boat or the check-in luggage.
Careful with check-in luggage. Apparently it might be mistaken for crystal meth [1].
[1] https://www.huffpost.com/entry/man-jailed-in-bust-of-the-yea...
Can't see this headline without thinking of my favorite cartoon of all time https://www.reddit.com/r/me_irl/comments/sqap29/me_irl/
Ah, seeing that (apparently like-minded amiga386) came here to post the same thing: https://onegianthand.com/post/188730414621/silica-gel
Starting to put these in my hygroscopic fertilizers was a game changer. No more bricks of unusable waterlogged crap after a few years. You can regenerate the beads in the microwave and you can buy color-changing ones on Amazon that indicate their status.
"I ate the DO NOT EAT packet in my pepperoni. Am I going to die?"
"Well, everyone's going to die eventually."
"Everyone? Oh my God... WHAT HAVE I DONE?!?"
https://explosm.net/comics/rob-pepperoni
archive link
https://web.archive.org/web/20250401195714/https://www.scope...
Why does it have the words DON'T EAT printed on every single package? you don't usually come across such warnings on other products.
Probably because they look like candy, and they're packaged with food a lot?
Even if not packaged with food, these sachects left on the table while unboxing, e.g. a pair of shoes, might entice kids... And it's just easier to print "DO NOT EAT" rather than have separate production lines for "for shoes" and "for food".
Although, from the description, it seems they're perfectly safe (because they're inert) to eat...
I realized this week for the first time exactly why. there was one in my instant ramen along with its other seasoning packets. If not paying attention you could easily be having your noodles with added desiccant flavor.
Yep, my mother in law did.
Also used with food stuff. So just producing one SKU with "DO NOT EAT" saves money and doesn't really hurt in other use.
Your body likes having water inside of it, and doesn't like having glass shards inside of it
Actually they are quite safe to eat.
https://www.theguardian.com/notesandqueries/query/0,,-186193...
In small quantities. As somebody already pointed, your body likes to keep its water inside it, it also doesn't like when stuff carries large quantities of unmixed digestive fluids from one part of your body to another.
They are probably quite harmful if large pieces get eaten in non-small quantities. Or powder in large quantities that are not previously mixed with a liquid. But I don't know of anybody that tested that.
You can also ingest up to one cup of gasoline.
You can ingest a litre of boiling oil.
well, i hoped i implied "without major injury". or so i've heard. I don't particularly like the flavor so i have avoided drinking gasoline thus far.
With millions and millions of those things around I’d guess quite a few get ingested accidentally and we don’t hear of them causing problems. It must be pretty safe (well as safe as eating a small amount of sand is).
https://www.theguardian.com/notesandqueries/query/0,,-186193...
The packets look like the little salt packets that come with fast food, and the stuff inside looks kind of like salt.
It's a choking hazard that is sometimes included in food packaging so it's just to cover the manufacturer since they don't really know what products it may end up in. Silica gel is non-toxic although maybe could cause some issues if you deliberately ate a huge quantity of it.
Before I had kids I wondered this. But it's really telling you to make sure your kids don't eat it.
I'm pretty sure it's just following the rules of the strictest food packaging laws among the places they expect them to end up. In some jurisdictions non-food that is directly inside a package along with food needs to be labeled that way. So they just do em all like that.
Lets not forget the MST3k silica gel skit in: https://mst3k.fandom.com/wiki/MST3K_1103_-_The_Time_Traveler...
https://www.dailymotion.com/video/x8hb1jh @ 00:02:00
The word desicant is burned into my mind from this guy talking about building some AC system
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