Adding Water to Contaminated IPA Produces Precipitate


I’ve been using my company’s Form2 for quite some time now, and so far, I’ve been taking care of my used alchohol by allowing free floating resin to settle and reusing the cleaner alchohol I’ve poured off, then exposing the smaller amount of high concentrate IPA to sunlight.

When cleaning my wash tank, I notice when high concentrations of water come in contact with contaminated IPA, a precipitate of some kind is formed. I’m doing testing to see if this precipitate is the dissolved resin. If it is, I’m hoping it can be then filtered off and the aqueous ipa without resin can just be disposed of down the sink, as I don’t have a distilling solution.

Does anyone know for sure what this precipitate is? or know any other ways that don’t require chemical apparatus to recycle/dispose of IPA without using expensive hazardous waste disposal services.

Thanks in advance.

Almost certainly the precipitate is resin, but you shouldn’t be disposing of IPA down the sink. Collect your used IPA in a sealed 5-gallon bucket (you can pick one of these up easily at any home improvement store). Many municipalities offer disposal of household hazardous waste for free. Make the monthly trip - it’s worth it.

Is it purely the IPA that is bad for the sink, or the resin mixed with it?

Hey @wdavies92,

As far as I understand, Isopropyl Alcohol could be poured down a drain (although I am not a scientist so you should do some fact-checking to be safe). We do have a page on Safe Disposal of Contaminated Resin that I would advise looking at.

From our page: Do not pour liquid or partially cured resin into drains or dispose of it with household waste. Do not pour isopropyl alcohol (IPA) that contains dissolved resin into drains or dispose of it with household waste. Safe and appropriate disposal methods of used IPA vary by location.

Noted, thanks.

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Also, since Alcohol and water are fully miscible (they mix together entirely in any relative proportions), if you add water to your IPA, irrespective of what precipitates out the remaining IPA will be heavily contaminated with water and to be useful for subsequent print cleaning would need distillation to remove the water.

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Corey_M is correct about IPA being poured down the drain. For unused IPA the current EPA guidance for disposal is pour it down the drain a little at a time with plenty of water. That was changed just a few years ago from having to call a disposal company. Also as he mentioned, do not pour used IPA down the drain. I’m having to do the same thing as RvLAutoriv to dispose of my companies used IPA. What I’ve found is that if you pour off the cleaner IPA you can cure the left behind resin by leaving the open bottle out in the sun for a few weeks. The alcohol evaporates off and the remaining resin will then dry out and cure. The cured resin can then be disposed of. Realistically distilling the IPA would be the best option.