Curing used IPA in form curer

Hello everybody,

I was trying to catch on the forum a way to recycle my used IPA after washing printed parts. I saw some interesting ideas and I thought I could do it in a simple way. Anyway I am afraid of possible risks, so I want to ask some advice. For the record, I asked one of my supervisors and he agreed with me :sweat_smile:
I just poured used IPA inside a glass container with a cap, then put it inside the form curer and set it on (with UVs-only for 15 minutes, heater off). One thing I am afraid of is that after using it, the glass container was a bit warm (again, heater was off all the time) and also the air in the curer was definitely warm.

I was able to “recycle” about 1L of IPA, but I cannot really see any visual difference between the “clean” and “dirty” solvent. Also, I’m using Flexible 80A resin which is quite transparent, so I don’t expect much change in IPA colour.

Having said that:

  • do you think it is a safe procedure? (IPA could become hot and ignite?)
  • do you have any suggestions/recommendations?

Thanks in advance

I forgot to say that after curing, I poured the resin into another tank and using a kitchen strainer. Then I checked the possible difference in colour.

Hi @pposabella,

Thanks for reaching out about ways to recycle the IPA! I will say to please be very careful with IPA near any sort of heat source, especially the Form Cure. Although the heat was turned off, putting any volatile/flammable liquid near a heat source is definitely not advised for safety reasons, and we are hesitant to even put parts wet with IPA directly into the Cure.

A safer alternative would be to sun-cure the container of IPA (which I have tried in the past which separates some, not all, of the resin in the IPA into a sort of blubber-like material) to cure the resin; this isn’t a great method however, and I found that my IPA also looked about the same after the process. I am not sure how effective straining through something like a coffee filter would be, but that might be worth a shot?

We don’t really have a method that we advise to recycle IPA, but I would love to hear more users’ experience with this!

If the resin is still mixed with the IPA, if you cure it you’ll end up with a big rubbery blob of partially cured resin and IPA. It is possible to extract most of the IPA from the rubbery blob, but it’s messy, slow, and not really worth the effort (you basically have to let the IPA leech out over time).

So before you try and cure your IPA, you need to give it a couple of days for the resin that’s mixed in (but denser than the IPA) to settle to the bottom of the wash tank. If you do this, and then sun cure the wash tank, you should end up with a rubbery blob of cured resin at the bottom of the tank and you can just pour off the “good” IPA and then dispose of what remains in the bottom of the bucket.

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Hey @Randy_Cohen,

Yeah that was my experience; I use the Finishing Kit buckets for my home set-up and let the bucket sit un-agitated for a couple of days before trying this method. I then fished out the blob with the strainer basket but didn’t think to try to squeeze any viable IPA out of it (mostly because I was horrified at the texture of the IPA blob that I had spawned :laughing: )

IPA is a highly flammable liquid and vapor. I suggest you search it out. Also, there might be a U-Tube on someone that didn’t realize the full meaning of the terms. Your question reminded me to get a chemical fire extinguisher standby. Thanks

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Thanks for all your comments. I was just concerned about the high amount of IPA basically wasted with no re-use. But safety first, I will try to cure it in the sunlight

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