Anyone who does resin printing knows that an inconvenient side effect of the cleaning process is accumulating large amounts of cloudy, goopy, resin-saturated isopropyl alcohol. Iso alcohol is needed to get the excess resin off printed models, but the alcohol doesn't dissolve the resin, it just dilutes it and makes it less viscous to aid in washing it off.
The more dirty alcohol you accumulate, the more clean stuff you have to buy to replace it, and at $100 AUD per 20L, for me it can become a bit of a financial drain.
And what do you do with this old iso alcohol? Some say to let it sit for a while to let the sediment settle to the bottom, pour off the clear stuff and then turf what's left. That seems like a bit of a waste, and I sure hope people aren't pouring that sediment down the sink. Others say to expose it to UV light so that the resin inside will form into a more solid sediment which can then be filtered out of the alcohol.
I've tried a few different methods, and been unsatisfied and frustrated with all of them. I've tried using coffee filters, but they get gummed-up so fast they stop filtering, and even when they are filtering, the stuff that comes out still looks like a milkshake. So I decided to try something different: distillation.
For anyone not familiar, distillation is where you heat the alcohol until it reaches boiling point and vaporises. In the instance of isporopyl alcohol, that's 82.3ºC. The vapour is completely pure, and all of the goopy, resin gunk is left behind. You then cool that vapour so that it condenses back into a liquid and collect it in a receptacle.
There are purpose-built devices for this, but I decided to "MacGyver" my own from household stuff. I used an off-the-shelf kitchen pressure cooker (the most expensive item in this build at $70 AUD), 5 metres of 8mm vinyl hose for $18, and a 5 litre bucket for $4.50. $92.50 all up.
I started by drilling a hole near the bottom of the bucket. The bucket would serve as the holder for the coiled hose, as well as the cooling system, by filling it with water (the faster you can cool the alcohol vapour, the faster it will condense into a liquid and less will be lost into the atmosphere). I fed the hose out the hole in the bucket and then sealed it with some hot glue.
Next I 3D printed four holders for the pipe. These would keep the hose arranged as a coil, so that the distilled alcohol could flow down and out the end of the pipe.
The pressure cooker I purchased has a safety vent in the middle of the lid. By a stroke of pure luck, that vent is the perfect size for the 8mm hose I had (I purchased the hose first).
So, the cloudy alcohol goes into the pressure cooker, gets brought to boiling point, the vapour comes up though the vent, into the hose and then through the spiral cooling system. It condenses into a liquid and collects into a receptacle at the end of the hose for re-use. It's simple science, and it works.
So now comes the FAQ:
Q: How clean is the alcohol that comes out from the distiller?
A: Crystal clear. Like it's straight from a new bottle.
Q: Do you lose any?
A: Yes, but the amount depends on the efficiency of the cooling, whether any vapour is escaping and just how dirty your alcohol was to begin with. In my tests I managed to get about 800ml of clean alcohol from 1 litre of dirty alcohol, so 80% retrieval.
Q: How long does it take?
A: It takes about 30 minutes to distill one litre. You can speed it up, but if your cooling isn't good enough you can lose alcohol that hasn't condensed and escapes out the end of the pipe as vapour.
Q: What is left in the saucepan after the distillation process?
A: That depends. If you catch it in time, there will be a horrible, goopy gunk that needs to be wiped up with paper towels and thrown away. If you let it go for too long, you end up with a crusty, bubbly, burned, toxic waste sediment that will become part of your pressure cooker for eternity. You'll have to scrape as much of it off as you can and throw it away. Definitely better than pouring it down the sink though.
Q: What will my wife think if I try this with her pressure cooker?
A: Please don't do that.
Q: Is it safe?
A: Not really. If you have your temperature too high, you could fill your kitchen with alcohol fumes, which aren't good. And alcohol is flammable, so be bloody careful.
Q: Any caveats?
A: DO NOT DO THIS WITH A GAS COOKER! Isopropyl alcohol is flammable, so you will probably burn your house down.
Q. Have you had any problems?
A. Not really, but now I seem to be able to smell colours. Not sure if that's a bad thing.
The more dirty alcohol you accumulate, the more clean stuff you have to buy to replace it, and at $100 AUD per 20L, for me it can become a bit of a financial drain.
And what do you do with this old iso alcohol? Some say to let it sit for a while to let the sediment settle to the bottom, pour off the clear stuff and then turf what's left. That seems like a bit of a waste, and I sure hope people aren't pouring that sediment down the sink. Others say to expose it to UV light so that the resin inside will form into a more solid sediment which can then be filtered out of the alcohol.
I've tried a few different methods, and been unsatisfied and frustrated with all of them. I've tried using coffee filters, but they get gummed-up so fast they stop filtering, and even when they are filtering, the stuff that comes out still looks like a milkshake. So I decided to try something different: distillation.
For anyone not familiar, distillation is where you heat the alcohol until it reaches boiling point and vaporises. In the instance of isporopyl alcohol, that's 82.3ºC. The vapour is completely pure, and all of the goopy, resin gunk is left behind. You then cool that vapour so that it condenses back into a liquid and collect it in a receptacle.
There are purpose-built devices for this, but I decided to "MacGyver" my own from household stuff. I used an off-the-shelf kitchen pressure cooker (the most expensive item in this build at $70 AUD), 5 metres of 8mm vinyl hose for $18, and a 5 litre bucket for $4.50. $92.50 all up.
I started by drilling a hole near the bottom of the bucket. The bucket would serve as the holder for the coiled hose, as well as the cooling system, by filling it with water (the faster you can cool the alcohol vapour, the faster it will condense into a liquid and less will be lost into the atmosphere). I fed the hose out the hole in the bucket and then sealed it with some hot glue.
Next I 3D printed four holders for the pipe. These would keep the hose arranged as a coil, so that the distilled alcohol could flow down and out the end of the pipe.
The pressure cooker I purchased has a safety vent in the middle of the lid. By a stroke of pure luck, that vent is the perfect size for the 8mm hose I had (I purchased the hose first).
So, the cloudy alcohol goes into the pressure cooker, gets brought to boiling point, the vapour comes up though the vent, into the hose and then through the spiral cooling system. It condenses into a liquid and collects into a receptacle at the end of the hose for re-use. It's simple science, and it works.
So now comes the FAQ:
Q: How clean is the alcohol that comes out from the distiller?
A: Crystal clear. Like it's straight from a new bottle.
Q: Do you lose any?
A: Yes, but the amount depends on the efficiency of the cooling, whether any vapour is escaping and just how dirty your alcohol was to begin with. In my tests I managed to get about 800ml of clean alcohol from 1 litre of dirty alcohol, so 80% retrieval.
Q: How long does it take?
A: It takes about 30 minutes to distill one litre. You can speed it up, but if your cooling isn't good enough you can lose alcohol that hasn't condensed and escapes out the end of the pipe as vapour.
Q: What is left in the saucepan after the distillation process?
A: That depends. If you catch it in time, there will be a horrible, goopy gunk that needs to be wiped up with paper towels and thrown away. If you let it go for too long, you end up with a crusty, bubbly, burned, toxic waste sediment that will become part of your pressure cooker for eternity. You'll have to scrape as much of it off as you can and throw it away. Definitely better than pouring it down the sink though.
Q: What will my wife think if I try this with her pressure cooker?
A: Please don't do that.
Q: Is it safe?
A: Not really. If you have your temperature too high, you could fill your kitchen with alcohol fumes, which aren't good. And alcohol is flammable, so be bloody careful.
Q: Any caveats?
A: DO NOT DO THIS WITH A GAS COOKER! Isopropyl alcohol is flammable, so you will probably burn your house down.
Q. Have you had any problems?
A. Not really, but now I seem to be able to smell colours. Not sure if that's a bad thing.
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