Cleaning isopropyl alcohol for reuse

3D Printing
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I’m wondering what’s the best way to clean isopropyl alcohol so that it can be reused to clean more prints?

Currently I have a pre-wash tub which I use to remove the worst of the uncured resin before I put models in to the wash station. This way, there is a small amount of IPA to dispose of frequently and a larger amount to dispose of infrequently.

I’d like to clean it for reuse though and wondered whether one of the cheap devices sold for making distilled water might be safe to use, probably outside to reduce the risk of an explosive atmosphere. They are heated by an element rather than a flame. Anyone used one of these?

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I’ve been following updates on this on hack-a-day for a few years, even though I don’t have a resin printer and am merely curious. :roll_eyes:

According to some of the comments, some jurisdiction don’t like distilling alcohol and don’t distinguish whether it’s ethanol :grimacing: but also " I (and others) have actually tried distillation…Even those who claim success are only able to recover, at most, half the IPA they put in. While I used a water distiller, it had an adjustable temperature, so I set it to the boiling point of IPA. Still wasn’t reliable."

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Thanks Michael, those are interesting - the filter one looks more likely to succeed I would guess. I’ll look in to it more.

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I reuse my IPA by using a Voss artesian water glass container. Because it is tall, over a
week or so the resin residue settles to the bottom of the container leave the upper IPA clear.

Voss Artesian Water

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Thanks Mark, I can’t get the link to work for some reason but are you just talking about a 500ml glass bottle? - I’ve got 15 to 20 litres to clean so I was assuming something larger. Do you expose the IPA to UV during that week - e.g. leave it in the sunshine?

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The best but also most annoying method I’ve found is to leave murky resin-filled IPA to rest untouched in a clear container for a month or two. A lot of the resin settles out. Then I pour off the clear part into a separate container. The remainder I leave out in the sun with no lid for a few days until it firms up and the IPA evaporates a bit. The remaining sludge is toxic waste but usually I recover more than half of the original murky IPA in a clean enough form to reuse.

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800ml bottle. I’m basically doing what @trevorflowers is doing - letting it sit so that the resin (heavy) goes to the bottom while IPA at top goes clear. Keep in mind this is just to store used resin - I’m continually using fresh IPA and adding it (when used) to the bottle.