Clean Up Your Resin-Printing Rinse With Dialysis

There’s a lot to like about resin 3D printing. There are many advantages to resin 3D printing, including the fine detail, smooth finish and mechanical simplicity compared to FDM. Resin printing has its downsides. Not least is the toxic waste it generates. What’s one to do with all that resin-tainted alcohol left over from curing prints?

What about putting it through a homebrew filtering device to get it ready for reuse. [Involute] likens this process to dialysis, and while we see the similarities, what’s going on here is a lot simpler than the process used to filter wastes from the blood in patients with failing kidneys — there are no semipermeable membranes used here. It’s not that this idea has been weakened by its simplicity. Instead, it simply removes non-polymerized acrylic resin using the same process as used for printing.

[Involute] I did some experiments in order to find out what happened to IPA that was exposed to ultraviolet light. The video below shows the results — the unreacted resin quickly clumps, making it easy to filter out of the IPA. The actual implementation of this process is a little more complicated. To achieve the desired cross-linking effect, the resin must be pumped through UV LEDs wrapped around a clear vinyl tube. From there the plastic-IPA mixture passes through two filters, 5 microns followed by 0.5 microns, after which it’s ready for reuse. [Involute] also added a timer to control the pump, making this a walk-away process — although since IPA is pretty flammable, we’d probably stay close by.

At more than seven times the price of gasoline, 99% IPA isn’t something you want to be throwing away. Resin-tainted liquor should not be flushed down the sink. Something like this will not only help resin printers save money but also make their process greener. Kudos to [Involute] This is what I’m saying.