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3D printing

Isopropyl alcohol (IPA)

An alcohol for cleaning. In resin printing it washes liquid resin off freshly printed parts, and in filament printing it degreases the print plate.

Explained in more detail

Isopropyl alcohol, chemically 2-propanol and IPA for short, is a solvent that dissolves uncured resin. For washing resin, Formlabs recommends at least 90 % purity, while Phrozen and Elegoo specify 95 %. Two baths work well: a pre-wash bath for most of the resin and a clean final-wash bath. The resin content rises with every wash. Used IPA with dissolved resin belongs in hazardous waste collection and never down the drain. IPA is highly flammable, and according to the safety data sheet its flash point is 12 °C, which is below room temperature.

Where does the term come from?

The name comes from the isopropyl group to which the alcohol group is attached. The chemically correct name for the substance is 2-propanol. IPA is the English abbreviation for isopropyl alcohol.

In practice

  • According to Phrozen, soaking for too long can make resin parts brittle: in the wash station, at least 30 seconds but under 3 minutes per pass.
  • The IPA must have evaporated completely before post-curing, and Formlabs specifies at least 30 minutes of drying time.
  • No open flames and no fan heaters nearby, and always keep containers closed. Phrozen warns against heating wash stations with IPA.
  • Do not wash resin off skin with IPA, but with soap and water, as Formlabs advises.
  • For the print plate in filament printing, IPA is enough in between, and warm water with washing-up liquid degreases more thoroughly.

Not to be confused

Isopropyl alcohol is not the same as methylated spirits, which consists of denatured ethanol. For washing resin, resin manufacturers specify isopropyl alcohol or their own washing solutions; water-washable resin needs only water.

Frequently asked questions

What purity of isopropyl alcohol does resin need?

Formlabs recommends at least 90%, Phrozen and Elegoo give 95%.

How do I dispose of used IPA?

IPA containing dissolved resin belongs in hazardous waste collection, never down the drain. Your local waste disposal service can tell you how your municipality accepts solvents.