I had a tub of IPA that was used with Tough Resin. Since I live in a predominantly ethanol-using culture, IPA is a bit scarce and costly, so I try to recycle where I can. Unlike the Clear and Gray resins that I used before, Tough doesn’t seem to come out of solution. I left the IPA out in the sun for four days (during a 42C heatwave, no less) and it remained a cloudy mess that dried very sticky on the fingers. Then the proverbial lightbulb went off. I had all the right equipment just laying around:
A simple distiller - two jugs, a hotplate and some tubing. Just look at the difference between the source and result! It produces about a liter per hour, nothing lost to the air, and the end product dries clean as it does from the store. I’m too chuffed with the process actually working (and the fact that it came out of my brain of all places) to analyze whether the hotplate use cost is more than just buying new IPA or lament that I only thought of this during the year’s worst heat, so make of this what you will!
Behold the very thick sludge left behind. I periodically laugh in its face and remind it how its plans to befoul my IPA have failed so utterly against my superior intellect.
This is amazing. I had the same issue with Flexible Resin and this just might be how I recover my IPA. One concern though, isn’t it dangerous to heat IPA? How much heat did you use?
That’s the beauty of it. While I generally have no problem with building-destroying chemical setups in my spare bedroom, recycling IPA is quite safe, relatively, especially on an electric hotplate rather than an open flame. But even then, IPA boils at 80 deg. C, even lower than water’s 100 deg. So you could even set it up in a bain marie (double boiler) if you want and it would still work, and keep the IPA from any direct heat source.
I must say I’ve had the sludge outside my window since my last entry (16 days?) in full summer sun UV and it’s still soft and icky. The surface is dry to the touch, but I suspect if I poke hard enough it’ll break a surface layer and it’s back to sticky city!
It has to be exposed to sunlight / UV light. Lots of things can block that and prolong the curing time, such as the walls of the bucket.
I had about 100 mL of tough resin that we were getting rid of (sadly the printer kept saying we were empty), so I threw it in a clear container and it was 50% solid within just 10 minutes, and 100% by the time I went home. Mind you, it was all in direct sunlight.
Would be nice if FORMLABS would make the IPA - Chambers transparent istead of black, this way even the light from the lamps the in the room would cure the resin in the IPA.
I’ve put old disgusting resin into food sealer bags before. I have a sealer that I don’t use for food and it works great.
You just seal it when most of the air is out of the bag and lay it in the sun. If it doesn’t fully cure you can move the material around to get a fresh layer exposed. Once it’s solid you can just throw it in the trash.
Also, as long as I’m here, I should clarify that the distilling/sludge remnants were a result of the TOUGH resin. The original gray/clear/etc. resins do indeed precipitate out of the IPA in UV light leaving it reusable. The TOUGH resin with it’s seemingly very different chemistry, not so much. It does not come out of solution no matter how much UV you feed it. If you’ve had different luck with the TOUGH resin, I’d love to know!
At Formlabs, we go through a very large quantity of IPA as you can imagine We use solvent distillers from this company to minimize our waste http://www.uniram.com/solvent_recycler-auto.html. Note that these solve the sludge problem by evaporating the input solvent in a one time use plastic bag.
I hadn’t seen these low cost distillers meant for moonshine before. If it works well for you, please let us know, as we may recommend it to our customers.
It works quite well, and the fact that the IPA can be sufficiently heated for distillation in a water-based double-boiler is a big plus for anyone extra-concerned about safety. Plus there’s no open flame or exotic apparatus at all, so it appeals to my sense of economy as well as safety. I’ve got so much random junk in the workshop that it’s just great to put some of it to unexpected use.
As far as sludge goes, I’m sure that if I had let it distill more, it would have solidified even more, but I noticed a diminishing curve of returns as the final liquid boiled off.
Finally, don’t say “moonshine” too loud around here, the government is always looking for new things to tax!
