Any luck restoring effectiveness of silica packets?

I've been blessed/cursed by:

1. Being raised by parents who went through the Great Depression and almost never threw anything away that "might be useful" at some time in the future;
2. A wife who worked as a pharmacy technician for a decade and brought home, at my request, the silica gel packets and canisters.

Anyone ever try restoring the effectiveness of packets and/or canisters? If so:
1. How did you do it?
2. Was it worth the time, effort and cost?

Thanks, in advance, for your responses.

Steve

 

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Googling turned up this advice:

"Typically, a silica gel packet absorbs water (about 40 percent of its own weight) and loses its effectiveness. However, silica gel packets can be reactivated and reused repeatedly. You can restore your silica gel packets by placing them in the oven at 100 degrees Fahrenheit on a cookie [sheet] for an hour. This will help to dry out the beads so they can be reused over and over."

-https://www.wasteconnectionsmemphis.com/news/article/nine-ways-to-repurpose-silica-gel-packets-865

 

I wouldn't bother with those specifically because there's no way to know when they need to be recharged.

If I needed ones for small containers, I would just buy something like this:
https://www.amazon.com/Pack-Indicating-Silica-Packets-Desiccants/dp/B01LZAQPEY

2-3 hours in the oven at 200*F

 

I'm not real sure how well the canisters would hold up to prolonged heat. They may melt and make a big mess, but the packets can be used over and over by heating in the oven to dry them out.

 

Weight?

Dry them for a couple hours and then weigh them, write the dry weight on the packet.

When it gets 20% heavier, repeat...

 

I agree that you might be able to regenerate the packets, but you'd probably just melt the canisters. Although there are plenty of plastics that are good past water's boiling point, so if you've got a stove that does a good job of regulating temperature, and you pre-heat it to 180 or 200, you might be able to get away with it.

 

Some might be okay with that. I'm lazy; much easier to just look at it

 

It depends what you are protecting. Coins begin to tarnish at 2·6–16·6 torr ( mmHg) of water vapor, so coins are stored best between 0 and 3 mmHg water vapor. Many 'dry' storage conditions do not need to be that low. Cobalt chloride used as an indicator is commonly used at higher levels.

Paper contents such as currency, historical documents, etc. generally prefer about 40% moisture or they dry out and crumble over time. So if you have mixed goods, you might have to use a lot of ziplock bags and sacrificial zincolns for the coins. When they tarnish change the desiccator or recharge it.

Jim

 

I use Eva-Dry rechargeable desiccants. They have a color indicator that lets you know when to dry it out, which is done by plugging the unit into an electrical outlet.

https://www.amazon.com/Eva-dry-333-Renewable-Dehumidifier-2-PACK/dp/B00LVN7BM0?ref_=ast_bbp_dp

 

And the 900gm unit costs $23... What are your coins worth?

 

I would not use the throw-away dessicant packets but if you want to try to regenerate them in the oven, you will have to leave the oven door cracked to allow the moisture to get out of the oven, and you will have to use a low heat, no more than about 100 to 125F. Additionally, most electric ovens (don't try using a gas oven) have a heating element that glows red when it is on and generates significant radiant heat while it is heating up the oven. I doubt you will be able to control the temperature these packets are exposed to using a kitchen oven with the result that they will probably make a big smoky mess.

I use the small electrically-regenerated dessicant modules like Eva-Dry in my coin safes. They last about a month before I regenerate them. I open my safes about once every two or three days. Regeneration takes about 18 hours. During regeneration the outer casing of the plastic module reaches a steady-state temperature of about 110-120F-decidedly hot to the touch but you can keep your hand on it indefinitely. Been doing this about a year with no obvious issues with coins or the dessicant modules.

 

Thanks everyone. I experimented last evening but our oven doesn't have a setting below 170. So after she was done making something and had turned it off, I put both packets and canisters, on separate pans, in when the oven may have been about 300 degrees. I didn't leave the door open and forgot to weigh the packets first. Took them out this morning and two of the couple of dozen canisters had melted. No obvious charring of the packets.

But I get what you are saying, @GDJMSP, and what others have said. I can afford desiccant units, in fact I have bought several and used them in the past. I just wanted to know what would happen. I have a shoebox full of packets now that may or may not be effective. Maybe I'll throw them in a couple of my tool drawers.

Steve

 

Nice experiment. Now we know and thanks for sharing. Reminds me of the time I washed a bunch of used ammo casings and then stuck them in the oven to dry them out quicker. The dog and I were shocked about 30 minutes later when we heard a loud bang from the kitchen followed by the tinkling of brass casings rattling off every surface in the kitchen. Big dent in the oven door from when the live round went off. Fortunately, I was single at the time so the only flak I had to take was the reproachful look from the dog.

 

@Publius2, that's hilarious, now that we know no one got hurt. I was reading that over 90% of the annual Darwin Award winners and honorable mentions are males. I know why....

Steve

 

@Publius2 does the dog still hide when you turn on the oven?

Pets often have long memories of things like that....

 

I will now stop hi-jacking this thread, sorry about that. We could start another thread about "stupid stuff we did when young" which might become the longest thread ever

 

Silica gel traps and holds water by adsorption (ie attraction to the surface and pores of the silica gel particles) and the water can be released by heating the material. If you cut open the packets and poured the silica gel out into a small glass jar, you could put the jar with the gel into an oven overnight and regenerate it. I would not exceed 200 degrees F. Has anyone used molecular sieves?

 

That's a creative way to go about it ,Kentucky!

Molecular sieves - only in my life as an engineer. For us hobby folks, the practical (read economical) methods are silica gel dessicants and using electrical heat strips to keep the dew point inside the container high enough to prevent condensation. For guns, coins and paper, I don't like the heat strips because they are, perhaps unlikely, a source of fire and the power cord is just another penetration of the safe's perimeter.

 

I used to get quart size cans of silica gel which was used in refrigerant driers. I kept a couple such cans in my gun safe, with holes punched in the tops using a can opener. When it turned from pink to blue (or was it blue to pink?), I would just bake the granules on a cookie sheet in the oven for an hour or so at 250F or so, then after it had all changed color, put it back in the cans and back into the safe. Can safely do such procedure probably countless times with no risk.