Tripropylene glycol monomethyl ether (TPM) dissolves liquid resin, making it effective for washing parts printed on Formlabs SLA printers.

Depending on your use case and work environment, TPM may be a viable alternative to isopropyl alcohol (IPA) for washing parts using the Form Wash, the Form Wash L or the Finish Kit.

Tripropylene glycol monomethyl ether is a low-volatility, non-flammable, colorless, clear liquid with an ether odor and an oily feel. It can be washed off surfaces with water and soap.

TPM is typically supplied as a mixture of isomers. Tripropylene glycol monomethyl ether is known by different names depending on location and distributor:

• Methyltripropylene glycol
• Tripropylene glycol methyl ether

In the United States, TPM is considered non-hazardous under the criteria of the Federal OSHA Hazard Communication Standard 29CFR 1910.1200. TPM has a flash point of 111 °C (232 °F), meaning it is not considered a flammable liquid under the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) or EU Regulation EC 1272/2008 and does not need to be stored in a flammable liquid storage cabinet. As with any chemical, store TPM safely when not in use. Consult your supplier’s safety data sheet (SDS) and local regulations for appropriate storage and handling guidelines.

To handle TPM safely:

• Wear disposable non-reactive gloves (nitrile or neoprene) to handle TPM.
• Work in a well-ventilated area.
• Transfer TPM from larger containers with a siphon pump to avoid overfilling the wash bucket or other container.

Spilled TPM does not present an immediate fire or health hazard, but it does leave an oily residue that can be slippery. TPM evaporates very slowly, so the spill won’t dry by itself.

To clean a TPM spill:

1. Put on a pair of disposable nitrile gloves.
2. Absorb excess TPM with dry paper towels.
3. Clean up any remaining residue with wet paper towels.
4. Dispose of tools used to clean up a TPM spill (paper towels soaked with TPM, gloves coated in TPM) with hazardous waste according to local regulations.

Over time, TPM accumulates dissolved liquid resin, which reduces its efficacy. For best surface quality, replace TPM when it no longer fully cleans parts or its specific gravity rises above 1.000.

Disposal

To safely dispose of contaminated TPM:

1. Consult the safety data sheet (SDS) from the TPM supplier as the primary source of information.
2. Research your local regulations for hazardous waste disposal. This will most likely involve hiring a waste disposal service. For smaller amounts, check with your local waste disposal service to see if they have any suggestions for removal.
3. Inform your waste disposal service that your bottle contains TPM with small amounts of methacrylated monomers and oligomers (unpolymerized plastic resin) and trace amounts of photoinitiator. Have a copy of the Formlabs resin safety data sheet (SDS) on hand in case the disposal service attendant needs more information.

Recycling

For large volumes of TPM, consider using a solvent recycling system, which offers a cost-effective and more environmentally responsible alternative to paying for waste solvent disposal services. Solvent recycling systems use distillation and fractionation processes to remove solutes from waste solvents, making it possible to reuse the TPM to wash parts. The recycled TPM may still have small amounts of monomer in it. Recycling TPM reduces waste disposal costs, emissions that are required to produce solvents, and the cost of purchasing TPM.

• TPM Wash Solvent Safety Data Sheet
• European Parliament July 2015 Briefing - Understanding waste streams: Treatment of specific waste (only English)