Drying with silica gel

house34

house34

Well-Known Member
BobCajun said:
I wonder if it would help to put a bubbler in the salt solution to circulate the air through it inside the closed container. Just have to make sure the solution container is lightly covered so that the water droplets from the bursting bubbles don't get on the product.
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Possibly. I'm going to start out keeping it simple.
 
Silky T

Silky T

Well-Known Member
BobCajun said:
Has anyone tried using silica gel to dry Cannabis? From what I've read, it reaches equilibrium at about 35% water. So in theory you could absorb 35% of the water in the weed by using an equal weight of dried silica and the weed would come out as 65% moisture. Makes the ratios easy to remember, being exactly the same.

Why would I want to use the silica gel instead of open air? Smell, that's why, horrendous smell problems. So instead, why not keep all those terps contained in an airtight container so none of them get into the air? You would also get more fragrant weed.

A fairly large container would be in order, so the silica and weed could be in thin layers with high exposed surface area. I would put a screen above the silica with air space between, to put the weed on, and put a small PC fan in there to circulate the air. I'll try it next time actually, but for now it's just an idea. The silica gel is bought cheaply in the kitty litter section. The blue grains aren't really moisture indicating though, just fake dyed ones.
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I've started saving those packets that come in your stuff from Amazon for just that reason. Imma give it a try.
 
BobCajun

BobCajun

Well-Known Member
When I started this thread I hadn't tried calcium chloride yet, which is far better than silica, which is pretty much useless for drying weed. You can dry it down to 75% RH just with common salt. After that you can get it drier with calcium chloride or just use it for the whole drying. The important thing is to have a small fan in the container to keep the air moving or it takes a lot longer. Calcium chloride will take it right down to the 40% RH range if you let it go too long though, then you need to remoisten it. What happens is that the container of calcium chloride pellets, sold for dehumidifying small areas, gradually fills up with saturated water and you have to pour it off.
 
BobCajun

BobCajun

Well-Known Member
I guess it might work. It was a very long time ago that I tried it, maybe I just didn't do it right. It weighs a ton though, like having a bag of rocks. What I used was a bag of it sold as kitty litter or something in the pet section of a grocery store, so maybe not the best kind for drying stuff. I just remember it was heavy as hell. Calcium chloride works great though, just it's not practical to reuse it, it absorbs so much water that it would take a long time to dry it back down to chunks though I suppose it would be possible. I've read that people dry flowers by putting them in thin layers with paper towel on both sides with the silica gel between the layers, like a sandwich.
 
nunyabidness420

nunyabidness420

Well-Known Member
BobCajun said:
I guess it might work. It was a very long time ago that I tried it, maybe I just didn't do it right. It weighs a ton though, like having a bag of rocks. What I used was a bag of it sold as kitty litter or something in the pet section of a grocery store, so maybe not the best kind for drying stuff. I just remember it was heavy as hell. Calcium chloride works great though, just it's not practical to reuse it, it absorbs so much water that it would take a long time to dry it back down to chunks though I suppose it would be possible. I've read that people dry flowers by putting them in thin layers with paper towel on both sides with the silica gel between the layers, like a sandwich.
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It works.
The most I dried with silica gel was about 2 pounds.
You will need a lot of it though or else you'll have to keep drying it out.
Just about any kind of silica gel will get you to under 60% humidity.
It's not any faster than a dehumidifier but its cooler and once you have the box set up you can stick it in the corner and not have to worry about smell or introducing more mold on to the buds.
 
BobCajun

BobCajun

Well-Known Member
nunyabidness420 said:
It works.
The most I dried with silica gel was about 2 pounds.
You will need a lot of it though or else you'll have to keep drying it out.
Just about any kind of silica gel will get you to under 60% humidity.
It's not any faster than a dehumidifier but its cooler and once you have the box set up you can stick it in the corner and not have to worry about smell or introducing more mold on to the buds.
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Silica absorbs about 40% of its weight in water, calcium chloride absorbs about 3 times its weight, so you would need about 8 times as much silica. Silica is also dusty as hell when you pour it. I guess if you kept it in an aluminum pan while doing the drying then you wouldn't have to pour it more than the one time, just put the whole pan in the oven to dry it back out.
 
I

itsfreerealestate

Member
Thread revival time!
Situation? I have a grow about finish.
Problem? I have some family due to turn up right at the end of / possibly still during flowering who aren't pro freedom.

I'm currently racing to get flowering done in time but I'll have to run it right up to the last days and won't have time to hang it up.

The possible solution is that I do have some giant foil lined zip lock food bags that can hold 5kg a piece. They'll only be here a couple of days but I'll have to bag it in the meantime. I've done quite a bit of chemistry so am familiar with the various drying agents. Boveda is rather expensive and more of a post drying humidity stabiliser rather than an actual drying agent. I do like their storage can idea though.

Weed is ~75% water when wet. So 1kg = 750g water. Silica gel (when fully baked dry) will absorb up to ~35% of it's own weight in water, so 350g of water per kilo of gel. If 1kg of wet weed contains about 750g of water, and it needs drying to about 10%, 650g of water needs removing. So that's... 650g in a kilo of weed / 350g absorbing power per kilo of gel = 1.85kg of gel needed per kilo of weed.

Gel is much cheaper if you buy bulk packs rather than sachets. Avoid the colour changing kind of it as it uses heavy metal (chromium?) compounds in at least some of it to achieve that effect, so you dont want the dust from that on things you're going to smoke or eat.

I think I'll just dry the gel, empty it into something like a clean pillow case, zip tie it shut and add it to the foil bag.

Something to keep in mind is this graph. The absorbing power of the different dessicants changes based on the RH. However I'd imagine if you were to fill a zip lock bag with freshly felled weed, a lack of humidity isn't going to be an issue.

Hopefully this works okay.

Edit: An alternative to this would be cement. Which happens to absorb pretty much precisely the same amount of water as silica gel. There are drawbacks to it. 1.) Because it's super finely powdered, the absorption rate is actually lower because it reduces the ease with which water vapour can move through it. 2.) It's not easily redried (it needs baking in a kiln to drive the water molecules back off). Advantages? It's 100% ready to go out the bag, no pre-drying guesswork necessary. It's fairly cheap and readily available. The moisture is also chemically bonded, so it's impossible for it to start releasing moisture back into the container if it's warmed up.
 

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Budzbuddha

Budzbuddha

Well-Known Member
It’s just insane overthinking this …. Use the tried and true ways of slow drying up to 2 weeks , instead of trying To reinvent the wheel.
You risk goofing up on something with silica - you should know breathing silica causes lung and respiratory problems , like dyspnoea.

Breathing crystalline silica dust can cause silicosis, which in severe cases can be disabling, or even fatal.

But your lungs . Where in the hell did you get this idea from ?
SMH :wall:
 
HydroKid239

HydroKid239

Well-Known Member
itsfreerealestate said:
Thread revival time!
Situation? I have a grow about finish.
Problem? I have some family due to turn up right at the end of / possibly still during flowering who aren't pro freedom.

I'm currently racing to get flowering done in time but I'll have to run it right up to the last days and won't have time to hang it up.

The possible solution is that I do have some giant foil lined zip lock food bags that can hold 5kg a piece. They'll only be here a couple of days but I'll have to bag it in the meantime. I've done quite a bit of chemistry so am familiar with the various drying agents. Boveda is rather expensive and more of a post drying humidity stabiliser rather than an actual drying agent. I do like their storage can idea though.

Weed is ~75% water when wet. So 1kg = 750g water. Silica gel (when fully baked dry) will absorb up to ~35% of it's own weight in water, so 350g of water per kilo of gel. If 1kg of wet weed contains about 750g of water, and it needs drying to about 10%, 650g of water needs removing. So that's... 650g in a kilo of weed / 350g absorbing power per kilo of gel = 1.85kg of gel needed per kilo of weed.

Gel is much cheaper if you buy bulk packs rather than sachets. Avoid the colour changing kind of it as it uses heavy metal (chromium?) compounds in at least some of it to achieve that effect, so you dont want the dust from that on things you're going to smoke or eat.

I think I'll just dry the gel, empty it into something like a clean pillow case, zip tie it shut and add it to the foil bag.

Something to keep in mind is this graph. The absorbing power of the different dessicants changes based on the RH. However I'd imagine if you were to fill a zip lock bag with freshly felled weed, a lack of humidity isn't going to be an issue.

Hopefully this works okay.

Edit: An alternative to this would be cement. Which happens to absorb pretty much precisely the same amount of water as silica gel. There are drawbacks to it. 1.) Because it's super finely powdered, the absorption rate is actually lower because it reduces the ease with which water vapour can move through it. 2.) It's not easily redried (it needs baking in a kiln to drive the water molecules back off). Advantages? It's 100% ready to go out the bag, no pre-drying guesswork necessary. It's fairly cheap and readily available. The moisture is also chemically bonded, so it's impossible for it to start releasing moisture back into the container if it's warmed up.
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I’m now thinking of buying cement in bulk, bagging it & labeling it magic weed drying powder. Instagram here I come. :bigjoint:
 
I

itsfreerealestate

Member
Budzbuddha said:
It’s just insane overthinking this …. Use the tried and true ways of slow drying up to 2 weeks , instead of trying To reinvent the wheel.
You risk goofing up on something with silica - you should know breathing silica causes lung and respiratory problems , like dyspnoea.

Breathing crystalline silica dust can cause silicosis, which in severe cases can be disabling, or even fatal.

But your lungs . Where in the hell did you get this idea from ?
SMH :wall:
Click to expand...
Using silica gel to dry things isn't really new idea. I would just hang it up to dry but it's not an option at the moment due to the need for enhanced stealth.

The dust is only harmful when it's fine and airborne. The gel beds are far from inhalable and you can just pour them into a cloth bag to contain them in one place. So long as you don't powder them and dust your weed down with it, it won't even get on there.
 
Hook Daddy

Hook Daddy

Well-Known Member
Buy a thermoelectric wine fridge, dehumidifier and humidity controller. Dry as long and slow as you like, then cure in the same box until you need it again to dry. Very easy, mine cost me less than $300 total, I had to drill one hole, took about 3 hours to finish.
 
amneziaHaze

amneziaHaze

Well-Known Member
Option one dry in a room they dont have access. Option 2 if you will play with cement and silica then bake it in a oven it will taste the same
Option 3 put itin vacum bags freeze it until they leave.no guest will open the frezzer
 
I

itsfreerealestate

Member
Some interesting extra options. I'm planning to build a fully stealth framed in, built in perpetual grow chamber similar to the wine chiller idea as I progress through the building work on the house so it shouldn't be a problem again. And I kind of like the idea of a stealth plant incubator; I grow a lot of other plants as well so it'd be useful in general as a garden propagator.

Unfortunately, there are currently zero lockable doors or cupboards in place and the freezer is tiny. Hence the odd option. It'll only be in the bags a couple of days / week maximum so I imagine it'll be okay.
 
I

itsfreerealestate

Member
For the sake of all things cement based, long story short, don't try it; doesn't work very well at all.

I had a few days to air dry it, so I loaded into a cardboard box with a slot cut in one end and the ventilation fan + scrubber connected at the other to draw air over it. It would have helped if the air was warmer and dryer whilst doing this.

Then, I put about two kilos of fresh cement into a giant foil ziplock bag, the kind whey protein comes in, loaded the weed into a t-shirt with the openings tied shut, loaded that into the big ziplock, closed it up and left it for around a week at ~16°C (60°F). Result? Mold.

I opened the bag out of curiosity pretty much as soon as it was convenient to do so and am glad I didn't leave it any longer. The weed was still damp and I spotted the white patches pretty quickly.

I'm not sure if warming the bag up would actually make things better or worse. Essentially the weed didn't dry because it had clumped together and possibly because the vapor pressure of the water wasn't high enough to help it evaporate off. Surprisingly, the cement hadn't even really started to clump.

Leaving it somewhere warm would increase the possibility of mold and it's growth rate, but could accelerate the evaporation rate enough to offset that. If it was really warm, e.g. left in a black foil bag out in the sun, the temperature might get high enough to actually pasteurise the weed. Either which way, it's probably not a great idea. I did it mainly out of necessity, I definitely wouldn't choose to use that route again. Pretty annoying given that I had to listen to the cooling fan and bubbler running for four months none stop but there's not much else I could do about that.

If it was in something like a big storage tub spread out on a rack over silica gel, that would probably work quite a lot better. But I wouldn't run a fan or anything in there just with silica gel poured in as it may encourage silica dust to accumulate on the weed. I'd dump the silica into something like a pillow case first and tie it shut before loading it into the tub. It'd require a fair amount of freshly, fully baked silica gel to work.
 
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I

itsfreerealestate

Member
Finely powdered drying agent, contrary to normal reasoning, also doesn't work as well beads. Even though the usual assumption would be it should work better because it has a higher surface area, the problem is it doesn't as it starts absorbing moisture because it tends to develop a kind of mantle on the surface of rehydrated drying agent. I've observed this happening with some potassium hydroxide on microgram balance before.

The mass keeps going up as it absorbs water vapor and co2 from the air. But it actually went up quicker if I left the hydroxide in the original flake form it came in rather than when powdered.
 
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