Saving IPA when washing finished parts

I do a lot of prints, a lot. I’ve felt I needed to find a way to save on the IPA as I have had to change it out at least one a week because it has become weak from resin contamination.

One thing I did was make up a holder so I could position the finished prints, still on the build plate, at a 45/45 angle with one corner down which drains a lot of resin back into the resin tray. But not all of it.

After the build plate has set in the 45/45 holder for at least a half hour I now take the time to use the plastic scraper to get as much left resin off the build plate as I can. I scrape all clear area around the parts and especially the sides of the build plate. You’ll be surprised how much excess good resin you can get off of these areas. I scrape this off on the wiper so it goes back in the tray.

This has greatly extended the alcohol life in the Form Wash for at least another 2 to 3 days.

I just add another wash step with an old / used IPA. After i’m changing the IPA i’m saving the second bath for step #1. So now I have 3 bath’s, 1 used IPA and 2 more clean IPA. I first place it in the used IPA and then in the two bath’S. This is extending the life of the bath’s.

When I do need to change the bath, I’m disposing the first step IPA and place the used IPA from step 3.

In this way the massive resin residuals is getting off and keeping my two bath’s cleaner.

How do you dispose of the used IPA? It’s toxic and should not be poured down a drain, on the ground, in a public drain, etc. I distill my used IPA, harden the left over residue as that can be then be put in the general trash.

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Two options:

  1. left it over outside for a day in a wide container until it evaporate. Normaly a single use one and dispose it after there is no liquids left.

  2. dispose it to a chemical bin that is been treated properly.

We use 3 ultrasonic cleaners for our washing workflow.
The parts go from one to the other for 1 minute each. From the dirties to the cleanest.
We filter the IPA baths once per week, after the week-end, as lots particles settle at the bottom of the ultrasonic cleaners after a couple of days. We use 100 micron disposable paint strainers for this.
Once the dirty bath becomes really saturated, we discard its content to the chemical recycling unit and the empty ultrasonic device is filled with clean IPA and goes at the end of the line.
This gives us consistent result and really clean parts.
We burn through 5 liters of IPA per month.