Distilling and cleaning with TPM safer option than IPA?

General Discussion
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Hello, I’ve been looking into improving my workflow regarding the cleaning of resin prints. I have always used IPA but now since I print more my IPA gets saturated fast and on top of that it’s expensive as well.

I looked into distilling and filtration. But distillation methods seem unsafe to be able to do in an appartment. And filtration seems like a hassle to properly setup and I doubt its effectiveness in recycling. I finnaly stumbled upon this post on formlabs here where an alternative of IPA is mentioned its called Tripropylene glycol monomethyl ether (TPM) Article link: customer_v2

Since it’s not flammable I believe this could be a good alternative to be used in a distiller. I want to know if anyone has tried this? And wether there are other safety concerns or impracticalities that would result from this method of recycling vs IPA.

I also hear TPM is relatively safe to dispose of (when its not contaminated with uncured-resin) so that would be another advantage.

I would think that by distilling the TPM / resin mix you would be left with a goo like substance just like you would with IPA, chatgpt says you could mix that with Clay-based cat litter Sand or sawdust and then UV cure it. I believe it’s something worth trying since the moisture would be absorbed and therefore the UV light would be able to cure and solidify the resin right? And you’ll still have TPM mixed in there but likely not harmfull enough for it to be considered hazardous waste.

I’m really curious if people have tried it and if not is there a reason for it?
Because I believe if it could be recycled than it would be way safer and cheaper than IPA, even though TPM is more expensive if you recieve a good return in volume from the distillation procces you could end up saving more money in the long run.

For me this would offer a great solution and make 3d printing safer, cheaper and easier!

Let me know your thoughts!

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The main issue that I can see with attempting to distil TPM is its boiling point of 242.8°C. By comparison: IPA boils at 82.5°C. You’d need to put a lot more energy into boiling TPM than you would IPA. IPA’s boiling point being below that of water means that you can indirectly heat the vessel by using a water bath/jacket. This provides a degree of isolation between the heat source and the vessel containing the solvent, which offers an added degree of safety. You could always use a silicone oil bath/jacket instead of water to distil the TPM but this wouldn’t offer quite the same degree of safety due to liquid water’s naturally limiting max temp of 100°C.

Something else to consider is the autoignition temperatures of the two solvents. IPA has an autoignition temp of 399°C and TPM is 277°C. What would concern me would be as the TPM boiled away the mass being distilled would gradually increase in concentration. My hunch is that as this happens the temperature will rise (I don’t know this for a fact so it would need verifying). If this is the case then there’s a distinct possibility that the mixture could rise above the autoignition temperature!

You might be able to use vacuum distillation to get over these issues but that adds another level of complexity. TPM might also form an azeotrope with water so this might be something to investigate.

I hope this helps.

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I see I did not consider the boiling point of TPM, I guess there isnt really a safe option for comercial use when it comes to cleaning resin prints. Do you have a preffered method yourself when it comes to cleaning your prints? I looked into distilling IPA (https://www.youtube.com/watch?v=OJICX2-907I) but this video mentioned enough safety concerns for me to steer away from that idea.
Would you say by adding a water jacket this procces would be way safer and could be viable to do in an appartment? And are distillers with water jackets affordable?

Right now I’m using 3 containers which share rougly 5 L of IPA. But since I started selling my prints my volume has gone up, and my IPA gets dirty fast. This is a pain in the ass because it increases material cost, and makes it a hassle, filtering, curing, cleaning, and disposing of the IPA.
On top of that letting the IPA evaporate takes too much time, and I don’t llike the risk factor of leaving containers with flammable liquids out in the open air… I really wish there was a better option regarding this.

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I don’t really have a fixed print cleaning workflow. I tend to use variously TPM, DPM, Butyl Glycol and IPA as well as an aqueous solution of my own recipe which contains Butyl Glycol and UN90 surfactant in water. It depends on what I feel like at the time. I also sometimes use an ultrasonic bath to help clean inside holes etc. that can be hard to access manually (with a brush for example).

Industrial water jacketed distillers are certainly available but I’m not sure about small scale versions suitable for domestic use. I would definitely say that these would be inherently safer than directly heating the IPA. I don’t really do enough printing for it to have become an issue for me so I’ve not looked into it. I’m not sure about affordability - I expect that’s down to how much it saves you in IPA.

Yes, leaving it outside for the IPA to evaporate can take ages. It eventually turns into a gel and the evaporation rate from this is very slow. You could try adding a lot of water to it. I would expect this to make the dissolved resin fall out of solution. If you then expose it to sunlight or UV. I would expect the resin to harden into a solid mass, or at least into a dispersed solid that could be separated from the IPA/water phase. You still have the issue of disposing of the IPA/water mixture though so it might not be a viable solution for you. I’m just throwing ideas out there!

Hope this helps.

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Thanks a lot I appreciate all the info! I’m reading more and more through others posts regarding washing. And I never even heard of DPM until today. I think I will give it a shot for a couple of reasons: (vs IPA)

  • Lower Flammability:

    • Flash point of 75°C, much higher than IPA’s flash point, reducing fire risk.

  • Slower Evaporation Rate:

    • Lasts longer in cleaning applications, meaning less frequent replacement.

  • Lower Toxicity:

    • Fewer harmful fumes compared to IPA, making it safer to use in poorly ventilated areas.

  • Less Skin Irritation:

    • Gentler on the skin, less likely to cause dryness or irritation compared to IPA.

  • Effective Cleaning Power:

    • Works similarly to IPA in dissolving resin and cleaning 3D prints.

  • Less Residue on Prints:

    • Leaves fewer streaks or white marks on prints compared to IPA, making it ideal for post-processing.

  • Better for Extended Use:

    • Due to its slower evaporation, it is more economical over time because it requires less frequent refilling.

  • Improved Safety in Enclosed Spaces:

    • Safer in confined spaces (less risk of flash fires compared to IPA), making it better for home or laboratory use.

  • Better Resin Separation During Recycling:

    • Because it evaporates slowly, resin is easier to separate from the solvent, making recycling DPM more efficient.

  • Lower Autoignition Temperature:

    • Autoignition point of 287°C, making it less likely to ignite accidentally during distillation or exposure to heat.

Cons:
**It’s more expensive than IPA, cheapest I found in Europe is 50 euros for 5 Liters, Which is not that bad considering all the pro’s it offers.

** Slower drying times on the prints after washing.

I plan to add a ultrasonic cleaner to use with the DPM to get better results.

I will see how long the DPM stays effective and maybe in the future I will look for a way to safely distill the DPM as to properly recycle it.

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One thing I’ve found is to use a can of compressed air to blow off extra resin before you put it into the wash. My parts are small so a can of air is not expensive. For larger prints you may want to get an air compressor. You don’t need much PSI.

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Yeah I was thinking about adding a pre wash stage before I would put it in the ultrasonic cleaner, don’t know if compressed air is the best way for me, a bath of IPA or DPM might be easier. Although yes it does increase the chemical waste vs using compressed air. I just wonder if you don’t have problems with the resin splashing back at you when it’s being blown off the print in crevices and stuff. Thanks for the idea though it’s something to consider!

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With my can of air, it will just make the resin flow. It is very little pressure. I hold the build plate over the resin tank at an angle so resin drips back into the tank. I then wipe the build plate with paper towels just to remove the most resin I can before wash.

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Hi @bvoz,

This is a great discussion on alternative washing solvents and recycling methods for 3D printing! IPA can be expensive and challenging to manage, especially at higher print volumes. We use an IPA distiller at Formlabs to reduce the amount of bulk IPA we have to purchase to replenish our washes.

Regarding TPM, while it’s nonflammable and lasts longer than IPA, has a high boiling point of 242.8°C and makes distillation impractical for most users. As @mrwakefield mentioned, distilling TPM would require a lot more energy, and there are concerns about the temps rising past its autoignition point as the concentration increases. Vacuum distillation could help, but it adds complexity and cost, and not something I have firsthand experience/advice about.

If you’re looking for a safer, nonflammable alternative that’s easier to work with, you might want to check out Formlabs Resin Washing Solution. It’s designed to provide IPA-like cleaning performance while being nonflammable and having a higher saturation limit (20% vs. IPA’s 10%), meaning it lasts longer before needing to be replaced. Unlike IPA, it doesn’t evaporate, so a secondary water rinse is required to remove it from parts. You can find our recommended workflow here.

Where Resin Washing solution differs from TPM is in washing performance. TPM tends to leave parts with an oily surface. Our internal testing and beta users found Resin Washing Solution to provide much better wash quality, on par with IPA. The last time I checked, we were evaluating the recyclability of Resin Washing Solution. I will update here if I hear any news about that, I would also be curious of whether it can be distilled—though I can imagine it would pose similar challenges to TPM and the others mentioned in this thread.

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@henryqiu can the new wash solution be distilled and recycled? I may have asked this a long time ago but can’t remember what the answer was.

I’m assuming it might be a no like your explanation above for TPM.

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Hello, thank you for your suggestion!
Has formlabs done tests with their washing solution vs DPM?

I find it rather expensive, I see the argument that it lasts longer and is safer than IPA.
But 75 euro’s for 5 liters is a lot in my opinion.

IPA is 22 euro for 5L
And DPM is 32 euro for 5L

For 10 liters of DPM I would spend 63,94 euro (includes tax and shipping) Still cheaper than formlabs washing solution.

I must say I have not yet used DPM myself but from what I understand it is effective and provides the same advantages as the resin detergents we see on the market. Maybe it is not as thorough as them but with that big of a price difference I would choose DPM over any commercially available resin detergent that prices itself in the same range. Especially if we use a ultrasonic cleaner and add a quick final IPA wash/dip.

This method would probably deliver the same results but would be cheaper in the long run.

I read more through the forum and found a post which I will quote here:

You may find this of assistance - this is the workflow that we use:

1: Remove print from build platform
2: Put print (complete with supports) into the “rough” clean up container, which has two aquarium air bricks in the bottom and bubble air through for approximately 1 min. We now use DPM for this but did use IPA for a long time, we would only change the IPA in that bucket after approximately 4 Litres of print resin had been used. The latest batch of DPM has cleaned up parts created from approximately 10 litres of resin and its still going strong.

The air bubbles certainly help remove resin quickly.

3: Ultrasound clean using DPM, the time will depend on complexity but is never more that 6 min

4: Clean any residual DPM from surface by putting in final bucket of IPA, again bubbling air through it for approx 30seconds. IPA in this bucket lasts ages!!

5: Gently dry with airline

6: Postcure.

Very quick, and very easy.

DPM is a better solvent in our opinion than TPM (Greater solvent action of DPM, thats why TPM does not attack the powder coating on the Formwash, yet DPM does)

Both TPM and DPM are much better than IPA if used properly as part of the cleanup. We now only use IPA to wash any residual DPM from the surface (not uncured resin) as it evaporates much quicker than water being used to clean up any residual DPM, or just simply DPM being left to evaporate on its own. Both DPM and TPM outlast IPA by many times

The additional extra expenditure on DPM or TPM as against the price of IPA, will repay itself very quickly after any batch of printing, as it last much longer than IPA,

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The issue with bubbling air with IPA is that IPA is extremely hygroscopic…you are basically introducing moisture into the IPA and diluting its concentration by doing so meaning it will saturate earlier…although you are trading that off for mechanical agitation which is also an important part is removing uncured resin.

Not super relevant to what you posted, but just thought I would share that knowledge.

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Hi, I just wanted to update and say that KH7 is also effective in cleaning the resin prints. If you’re in europe this might be a good alternative to mean green or IPA. I have not tested how long the KH7 stays effective and it’s only a few euros cheaper than IPA where I live. I will also try DPM, I expect it to last longer and therefore be cheaper in the long run.

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So whats the reasoning for distilling IPA we just pour over saturated or dirty IPA into a waste barrel and get fresh from a new 55 gallon drum is it really saving that much money when you are taking the time to distill it.

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Depends on the cost of IPA where you’re at how easy it is to dispose of and how much you print/how quickly it becomes unusable

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It makes sense for me given the quantities I use and the space I have. IPA is expensive in Canada unless I buy huge barrels of it, which I don’t have space for.

It’s also better for the environment because waste facilities just burn your spent IPA.

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We spend I believe between 300-500 dollars per barrel of IPA and Acetone. We keep a empty one for the waste. Weve changed the IPA in the Form WashL twice since July but we have a big IPA wash tank as well for our SLA 5000 parts.so we go through a full barrel around 6 to 8 months and i know we dont have the time to distill the IPA. I believe its a couple hundred bucks for a company to pick up the full waste barrel. Im currently working on figuring a way to use our MjF waste powder stuff we dont put back into the machine but thats all personal projects for me.

Thank you for you input.

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It takes little to no effort to distill, you just need a distiller that’s big enough to handle your volume. You literally dump it in, hit a button and fresh IPA comes out.

The only time consuming part is cleaning out the wash tanks/buckets, but in my opinion, you should really be doing that anyway regardless of whether you’re tossing out or recycling the IPA.

For me, recycling is financially a win and responsibly/environmentally a win.

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If I recall, @leonhart88 even shared a video of his IPA distilling process

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Yeah I made a YouTube video a while back :slightly_smiling_face:: https://youtu.be/txSbP4tcukU

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