Reusing IPA

I was wondering if during IPA rinse there was a chemical reaction that changed the IPA - making it less effective, or, if the problem with used IPA was simply particulate (cure or uncured) resin contamination.

Guessing the latter, I pinged support. It seems that filtering IPA should allow you to get more use out of it.

I sit used resin in the sun to cure contaminant resign. It will tend to settle to the bottom.
I then filter it with coffee filters(which will catch particles down to 10 - 15 microns.

So far I’ve had not issues using filtered resin(I have not filtered resin over and over. I suspect efficacy will taper off, but this might be a way to get a little more use out of your IPA.


I’ve been putting my IPA wash tank inside my LED post-cure “jar”. I just strain the IPA through a paper towel after a few hours exposure. The results are excellent. I posted some pictures in this thread.

I’m not sure putting the IPA in the sun is a good idea. The heat might cause evaporation of the alcohol leaving more water in the tank. Even though the lid is on I would imagine the expansion of the alcohol would lift it enough to vent it off. The UV curing idea is better.

I’m building a UV curing box similar to Randy’s idea with the jar. I have adhesive 1/4" foam board that I added shiny prism aluminum coated paper to. This I have cut to make the sides, back, front, top and bottom of a 8"x8"x10" box. I have a roll of 16’ of UV LED lighting on the way in. The LED strip is adhesive backed so I will run that around the inside of the box on the sides, top and bottom. Should work just like Randy’s jar does. I’ll post photos when I get it built.

  • Walt

Yeah. Even in my Jar, the alcohol gets warm (It’s 24W of LEDs so it’s going to generate some decent heat). Not enough to blow the lid off the tank, but enough it makes an audible “gasp” when I open it up. If I’m going to leave it in the Jar for a while, I usually leave the lid loose so the tank can vent.

The one thing your box won’t do that the jar will do is allow you to cure under water, which is apparently recommended for the flexible resin. The jar is water tight… :stuck_out_tongue_winking_eye:

Still, when the IPA is open to air and especially heated it will evaporate the alcohol. So a 90% solution might end up being 85% and as it’s reused that will continue to go down some even with fresh IPA being added. I’m just saying after a number of curing it may eventually need to be disposed of.

On my UV curing, I don’t use my pieces like most do. Mine are strictly for casting masters. I may print six or eight of an item, depending on size, and use these to make a silicone master where I will cast quantity in two part resin. Masters then go in a drawer for when the silicone mold finally tears apart, after couple dozen uses, and a new mold will be made. Right now I’m curing in the sun which works ok as long as it’s a sunny day that is. :relaxed:

  • Walt

I put IPA back in its original container (translucent plastic bottle) and cap it before sitting it in the sun, so alcohol shouldn’t evaporate into the atmosphere too much.

Either way, i don’t think this allows for endless use of the same IPA, but it might allow a bit more use than I was getting.

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