this post was submitted on 26 Aug 2024
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TL;DR No.

What you should do:

  • buy fresh IPA. It is approx. $5/L. As such a 2L washing bin is approx. $10 + 10L waste disposal. In the broader picture of total costs and production value, this is manageable (resin cost, machine depreciation, PPE/gloves, ...)!
  • use two or three stages of washing
  • fill the washing containers with as little as necessary to get it done
  • periodically expose the liquid to sunlight and let the particles settle down. Separate the "clean" liquid from the sump (you might add special chemicals to speed up this process).
  • if the first stage needs replacement: 1.) responsible disposal of the liquid in compliance with local regulation 2.) move the liquids around: (the third stage is the new fresh liquid, the second is the prior third stage and the second washing station is now the first "dirty" stage).
  • check for alternative chemicals that can be used with your particular resin

If you use water-washable resin: IT IS A DANGEROUS LIQUID! Dispose of dirty water responsibly as chemical waste.

Long answer:

To answer that, let's first look at what isopropanol (IPA) is: Its formal name is propan-2-ol and its CAS number is 67-63-0.

As a starting point, check a database like GESTIS (German) and NOT wikipedia: https://gestis.dguv.de/data?name=011190

At the top of the page we see that it has GHS-02 and GHS-07 warning labels. Looking further, it is a colourless liquid with a flash point of 12°C and an ignition point of 425°C. The explosive range is 2-13.4% vol. The signal word is DANGER.

Scrolling down:

The substance forms explosive peroxides.

What does this mean?

There is no mechanism mentioned, but generally, if you expose these chemicals to sunlight they will react over time to form a peroxide, which is much more reactive and can explode at high concentrations (there are exceptions to this rule, but most of them go boom).

This means for distillation:

  • avoid "old" IPA if possible
  • check for peroxides (if necessary, treat the peroxides before distillation)
  • don't distill dry (leave some liquid in the sump to avoid high concentrations of peroxides)

As I believe this shouldn't be done at home I won't tell you how it can be safely done (if this isn't enough to deter you: read scientific literature/books describing how it shall be done).

Instead, focus further on what advice is out there on the internet/YouTube:

  • A water distiller is made for water and water isn't flammable and doesn't form explosive atmospheres. In other words they are unsafe for Isopropanol or Ethanol.
  • Do you think a 2kg fire extinguisher is enough? Are you truly capable of thinking rationally when there is a fire or would you panic like most people?
  • Don't even consider doing it indoors or in a garage.
  • Don't work with large volumes. In a laboratory with proper fumehoods and equipment, there might be limits like 500mL batch sizes.
  • If somebody isn't wearing eye protection or heating large amounts of liquid without stirring question his qualification to talk about this topic. Being an influencer or posting online, like this post, doesn't require any formal qualification as such even the big YouTubers/influencers post horrendous content that is dangerous or misleading.
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