So every couple months I clean my resin contaminated alcohol using alum powder (link to a video about the process)
After cleaning it I let it sit in the settling containers until I need to clean my alcohol again. At which point I swap the alcohol that was cleaned into my main wash and cure station tub and then put the dirty alcohol into the other tub I use exclusively for cleaning the alcohol.
Edit: For those curious I can share an image of what the alcohol looks like after it’s had 24 hours to settle in the settling containers.
Can’t watch the video at work, but I suspect the video is about coagualtion & flocculation. The resin is coagulated from disolved resin particles into suspended resin-alum complex particles too heavy to remain suspended in solution, which is why a small-scale settling pond works.
It’d might be a bit quicker/easier to put it through a filter or series of paper filters. Nothing crazy. Even a coffee filter should get most of it. Micron scale filters aren’t terribly expensive but clog quickly, so it’s best to run a coarser filter to get most of the big chucks first. Granted, not sure how long the coagulation process takes versus the flocculation process. If the coagualtion process is slow but the flocculation process is fast, filters probably won’t save much time. Though they may make cleanup easier.
Eventually, the IPA will be diluted with water from the aqueous alum solution (I assume he’s using an aqueous solution as alum is barely to not alchohol soluable). There’s the salt trick to separate the azeotrope, but I haven’t personally tried it.
Lots of work, but still better than those guys who distill the dirty IPA with non-explosion proof apparatuses. shudders in OSHA
You’re right about what it talks about
Eventually it will dilute too much to be effective for resin but that will take awhile I think
Personally I use about 25ml (it’s more concentrated than in the video) per liter (I do 4L at a time) so it will take a long time to get too dilute as I started with 95% alcohol (I’ve heard of people going as low as 70% and still being fine for cleaning resin prints)
Those people I see distilling IPA with nowhere near a proper safety setup makes me sweat for sure. I’ve distilled a lot of alcohol (not for resin, for other reasons) and it can quickly go to shit without specific levels of control. And you need to have a lot of safety procedures in place just in case.
If I was to distill my resin contaminated alcohol I’d try to purify it as much as possible before distilling to bring it closer to known variables for me. But it will be awhile before I do that as the gear I’d use for it would be dedicated to that purpose specifically from that point onward.
Also I use just ethanol as I have an easier time getting my hands on it in large quantities, it works great for resin as well and it’s not as gnarly as IPA.