Alternate Wash Solution

What kind of use are you getting out of it? The issue we’re having in the Form Wash with IPA is we are seeing residual resin pooling near holes after as little as 5-10 part washes. If the DPM/TPM lasts 5 times as long, it may be worth it. I’ve also started looking at ultrasonic use instead, but haven’t come up with a viable work flow.

And just to add, resin contaminated IPA is treated as hazardous waste and disposed accordingly. If someone has a better disposal method I’d love to hear about it.

I’m not sure exactly how many times but I’m sure DPM lasts at least 5 times IPA(another company claims 10x), i think TPM lasts a little bit less longer than DPM, Formlabs has data about it.

We had a problem with evaporation of IPA so we constantly had to fill the wash. Also we weren’t able to use all the resins in the same wash because as soon as you did rigid and ceramic prints, other prints would become contaminated with white residue.

We don’t have these issues anymore. We print once or twice a day and it takes several weeks before I have to replace the DPM(or at least filter it).

You will still have a bit of residual resin pools with TPM/DPM. It evaporates slowly so you have to rinse the part with water and then blow it with shop air. If you don’t do this then it can drop to corners and if you then cure it… your corners will be filled with cured resin.

Not having to bother with constant IPA replacement and being able to just put all the resins together is the biggest plus for us.


My personal experience has shown that TPM can last about 3x as long as IPA. The fact that it evaporates negligibly also reduces solvent usage.

There’s some learning curve to switching from IPA to TPM. My first week or so was pretty frustrating, but as soon as I learned the differences in the wash process it was good. Now I almost exclusively use TPM.

I haven’t used DPM myself, but I have heard of some compatibility issues with the material finish on the Form Wash fork.


Definitely true. The powder coating over the steel of the fork of the form wash will release.
There was hardly any info when we started using DPM so we learned it the hard way. We’re using DPM for quite a few month already and the coating was completely released in the first month or so. It doesn’t really affect the function of the Form wash, but it doesn’t look very pretty too.

We also found out that you should never put a part directly from the form wash into the form cure after using shop air. It seems to fog the reflective mirror and some of the DPM/resin mix will drop slowly into the metal grill and start to cure. Something you don’t have to worry about with IPA as the IPA would have been evaporated already.

Reading though the article, I see many of these things are mentioned and it almost perfectly matches our experience. With DPM, my parts feel dry(not waxy) within 10 hours after a water rinse and no cure. Washing for 15 minutes. But it could be an environment difference you guys tested it in compared to us.

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Hey Craig! You can’t just say you sorted out a wash process and not fill in the details!

I actually use a Prusa SL1 but I’m confident the TPM approach is going to be better than IPA (so long as it works with castable resins).

I’ve got some on order, my plan is to ultrasonic the parts in the TPM for 10 mins or so, then water bath (spinning magnetic stir bar of sorts), then dry with air and cure. How does that sound to you?

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The only price I found for TPM in the USA was ~$46/liter. I’ll stick with IPA.

If you’re doing ultrasonic and not the form wash, try DPM. It costs us around 12.50 euro per liter and lasts longer.

The article explains very well how to use it.

If it’s any consolation, I can’t find it at all here in New Zealand. It doesn’t seem to be listed as a restricted/hazardous material as far as I can tell, just generally unavailable.

A lot of things on the market sold as paint thinners have a mix including DPM, but zero hits even for straight DPM I did find monopropylene glycol methyl ether which one might have been tempted to try, but its flash point is 31°C/88°F, oof.

99.9% IPA at $38 (including sales tax) for 5 litres is starting to seem like not a terrible deal.

Thanks; but I can get IPA for about $2.50 - $3 per liter,

The CAS number for the DPM we use is 34590-94-8.

Yes it is 5 times more expensive than IPA, but it also lasts much longer, doesn’t evaporate as quickly and gives our parts a better finish.

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Where do you buy it? I’d like to find someone in EU that would deliver to Croatia. I got a quote from a local dealer here in Croatia - for 700 EUR / 5L which is ridiculous. .

potopi model u slanu vodu :smiley:

Yes, but @fantasy2 specifically said “If you’re doing ultrasonic…”. and that is where a product like DPM pays for itself. IPA, like other highly flammable liquids has a low flash point and can catch on fire in an ultrasonic cleaner.

So unless you plan carefully watching it during the whole cleaning process with a fire extinguisher at the ready, I wouldn’t try it.

DPM on the other hand, has a much higher flash point than IPA is is saf(er) to use in a an ultrasonic cleaner.


Thanks. I found that, and 25498-49-1 for TPM. Remarkably few Google hits for those on .nz sites, or for the common abbreviations (DPM, TPM, TPGME), or the full name (with or without calling it “monomethyl ether” rather than “methyl ether”). Quite a few SDS PDFs for blended products (usually <10% one or the other), but that’s about it. I’ve been busy searching, but it hasn’t been helping :frowning:

A product like this paint thinner (10-20% w/w DPM) is the closest I’ve found to actually being able to purchase either (and hey, maybe this stuff would work as a resin solvent, but I wouldn’t bet the farm on it). I just don’t seem to be able to find any supplier for either straight DPM or TPM in this country.

I’m gonna sic my friend in procurement at work on it today and see if he can find anything, undoubtedly we have a contract with a chemical supply outfit. I also saw when I arrived people from the company that manages the water quality for our datacentre’s liquid cooling, probably have an in there too. Also need to call up the NZ Formlabs reseller (their shipment is due right about now and I’m clamouring to get my pre-ordered Form3) and see if they have a line on it.

The hunt continues. I’ll report back if I find anything, in case anyone else from NZ is searching. In the meantime this is the best NZ source for Isopropyl alcohol I’ve found:

Good point.

hah fair enough. For me, the main difference was making sure the parts were fully dry before going into the Form Cure. Because water and TPM evaporate much more slowly than IPA, it can be less obvious.

Crazy expensive stuff.

Try tap water with a jigger of household dishwashing liquid (we use AJAX) in a heated ultrasonic cleaner (60C) for 30 min. Bonus is that the supports pull off effortlessly, like wet spaghetti noodles. Follow with a quick cold water dunk, IPA dunk, then into the form wash w/IPA for 10 min. Works for FL grey and black resins, we haven’t tried others.

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  1. hot soap water
  2. cold water
  3. IPA
  4. formwash with IPA

I don’t know about your time, but it sounds way too complex compared to DPM/TPM+rinse -> done

@Multiscale: What do you do with the rinse water contaminated with resin?

With the detergent water, the resin does not go into solution to the extent it would with IPA (and maybe not at all, I’m an engineer not a chemist). It settles out to the bottom of the ultrasonic cleaner tank and is left behind after the machine has been drained (assuming you have a unit with a drain). Just wipe out the excess resin with a paper towel and dispose of that as usual. The remaining rinse water goes in open aluminum foil trays set outside in the sun. Allow the sun to cure any remaining resin out and evaporate the water over time. This leaves behind a crust of cured resin which can be then disposed of in trash. Similar to the way you treat resin-contaminated IPA.

May sound more complex than just tossing parts into IPA or TPM but it’s not. Once you experience the joy of removing wet sphagetti supports, you will not go back to cold processing and having to clip off hardened supports.

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