Cleaning vat , stuff stuck to bottom


Hey all. So yesterday was my first handful of prints. Id say im off to a decent start, though I’ve already made a few mistakes, and im hoping not to make another major blunder when cleaning my vat. First i accidentally printed the 4 moai instead of the 4 clyinder test, and wondered why it was taking so long. Then, when reading the leveling guide, i failed to realize the build layout in cura is flipped to how I look at it when it comes out of the machine, so all my #s i wrote down were backwards, and my adjustments were all wrong. Finally, since my adjustments WERE wrong, i eventally had C and D failing to print and didnt remember to try and clean them off the bottom of the vat before printing again. SO i had 2 failed prints go thru C and D and stick to the bottom.

So, now i have quite a stuck-on blob on the bottom of the vat. Finger pressure (with nitrile glove) wasnt enough to unstick it, and since i WAS aware of how delicate i keep reading the PDMS layer is, i just put the vat in a zipbag, with the resin, and left it overnight.

I did a bit more reading last night and this morning, so this is my plan based on what I’ve read…

-use a squeege to get most of the resin out.
-Filter it with something to get out any small bits.
-Use a paper business card or a “plastic razor” to gently try and remove the resin blob at the bottom of the vat.
-Clean the vat with denatured ethanol (is this stuff ok? it was all i could find as far as ethanol goes), and some baby wipes. Im thinking baby wipes because they have a much softer texture than paper towel. I was unable to find any large containers of IPA. All i have is the bottom of the bottle in my medicine cabinet we use for cuts and scrapes… and its only 70%.
-air dry, refill, adjust my backwards tightening from earlier, and reprint

any potential bad ideas there that i should avoid?



You can also GENTLY pry the cured resin off the vat with the scraper. However, use a shallow angle and NO down pressure, the edge of the scraper will engage the bonded resin and break the suction.

I wouldn’t use baby wipes as they have deodorant oils and soaps in them (I am assuming these are the pre-moistened variety). Shop paper towels (i.e. lint free) work well, as do household paper towels, if you dab rather than wipe.

As for denatured ethanol, depending on where you live the denaturant can be an essential oil, which may adhere to the PDMS. If you are in the United States, look for EverKleer (EverClear) in your local liquor store. It is 95% grain alcohol and (IMHO) only suited for solvent use. I clean my prints and vats with it without issue. It is not cheap (~$20) for 750mls, but…

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thanks for the quick reply PC.

good call on the baby wipes. these ones state ’ frangrance, alcohol and paraden free’… but whatever. i dont have shop towels, but i do have microfiber.

as for the the ethanol, im in canada. the ingredients on the ethanol bottle dont say anything about essential oils. it just says ‘denatured ehtanol’. but i suppose there is no way to know if the oil was the method they used to denature it. but, i had it around, and since i always thought it was just ethanol, it was going to be the cleaner i used. is there a safe test i can do somehow to determine if it will affect the PDMS? is the 70% IPA not a good substitute? IPA is pretty easy to come by in small bottles at the pharmacy.

i did think about using something from the liquor store, but figured id would be too expensive. i dont drink, so i dont realy know what alcohol costs, and wouldnt know what to look for. A quick search on the LCBO site doesnt show anything for Everclear, and google tells me we dont have it in canada. Seems there are lots of threads of people trying to get it, or other high proof alcohols in canada, so my options my be limited. Maybe someone else from Canada (Ontario) has some ideas?



What kind of “squeege” are you folks using? Interested in size, material, etc. The PDMS in one of my vats has accumulated some stubborn dust particulate that has resisted cleaning so far.



this was the one recommended in another thread.

… no idea if its any good, but if its been recommended i guess it cant be that bad. iv personally not tried it yet, but i was planning on ordering one. for now i will be using another soft rubber pad i have from my vinyl application days.



The denaturant is set by regulation, so you should be able to find out what it is online. If you are lucky, it may just be IPA. If, however, the denaturant is t-butyl alcohol, pyridine, or methanol, I would avoid it. I am not certain about pyridine, but methanol and t-BA can fog plastics.

IPA will work, but is harsher on the acrylic. Some people swear by it, but I have had issues with IPA and plastics in the past and won’t risk it. 70% IPA may be fine, it may not dissolve the unpolymerized resin as readily. Because I don’t use it, I cannnot share any experiences.



i did find this data sheet, but it seems to only deal with safety. i quickly scanned earlier today and didnt see anything about ingredients. i could email them and see what they can tell me.

i went ahead and did a wipe down with it either way. it seemed to be fine. i got some foggy smears, but that was more just from the water on the paper towel and the little bits of resin i couldnt quite get out of the corners. i wiped it down again with the questionable ethanol and that cleared up the smears 90%.

so ya, i was able to get the blobs off the vat, used my calipers on the build plate assembly corners itself (the part that tips… not sure whats its real name is) to get the screws back into close tolerances, then printed another few test prints and im now at 10.7 in all corners.

regarding the IPA, if 70% is too strong, could it not just be watered down? or does it not work like that? im no chemist. Iv read Mark say in a couple threads that IPA is safe.



I wouldn’t call 70% IPA “too strong”, it is a matter of the two polymers. The liquid resin is solubilized better by higher-concentration alcohol. On the flip side, the acrylic (depending on formulation) can be damaged by certain alcohols.

IPA has been used by others, apparently without issue. If it works for you or is the only thing you can get, then use it. However, just be aware that it may cause crazing of the acrylic.



I used IPA 70% and I wasn’t happy at all with the result. It cleans well but the PDMS layer became sticky (!). After that I tried a second print using the cleaned vat and the build plate kept sticking/sucking on it until it tore apart a slice of the PDMS layer… and the vat is now garbage. Maybe I used too much IPA to clean it but I’m looking now to find another product that may not interact with the PDMS.



IPA 70% is that not strong, however IPA is more corrosive (and toxic) than ethanol and that is why we always recommended Ethanol for clean prints and vats. Wiping IPA on average grade acrylic will cause hairline fractures and even for our vats, extended exposure IPA on the acrylic can cause small cracks.[]=cleaning



yesterday, before my original post, i read this…

Acrylic are not all made the same. The vat uses a type of acrylic that is optically clear and can withstand ipa/alcohol.

…from Peopoly. Im pretty sure I read it in another thread as well. Its a bit frustrating when there seems to be 2 answers to every question. Maybe that was old thinking from last year, but still, its out there as info directly from Peopoly



I use that squeegee. It is the right amount of soft and stiff to clean a vat without damage. Get a smaller one for recovering resin off the build plate at the end of a print. My one quibble: if resin gets under the “handle”, then you’ll never get it clean. However, you should be wearing gloves anyway.



The issue is perseverity of postings. Unfortunately, much has been learned since the Moai was released into the wild. The vat is, as I understand it, is made of two types of acrylic: the window acrylic being of the variety described in that quote, and the frame of a different variety. Since the frame acrylic is less critical in terms of optical quality, it may be more variable amongst suppliers. Again, YMMV. Some users only have IPA available and use it without issue.



what is means is that the vat acrylic is of higher quality than the panel acrylics. Try wipe that IPA on your panel and see it get hairline cracks very quickly. The vats can withstand ipa much better and is also optically clearer (not just because of the color). But if you submerge vat like some user did and leave it in for 30 mins then it may start to get some cracks. This information has been consistent from the beginning of Moai project.



@peopoly, when you say vat, i assume you mean the entire vat, walls and all, with PDMS layer, and when you say panel, im not sure what you mean… im guessing the black acrylic on the sides of the frame? why would anyone be submerging the side panels in IPA?

so again, here you’ve said the vat acrylic is of higher quality. so to me, this means i can wipe it with IPA. but 3 posts above you said wiping it on average acrylic and on the vats, may cause small cracks. sorry to be a pain on this, but again, conflicting information. so maybe the logic here should be that IPA is safe to WIPE OFF the vat with, but not for long exposure like submerging for any duration of time?

@Paradoxical_Cat, i heard back from recochem…

Thanks for your interest in Recochem Bio-Flame. The product is based on Ethanol denatured with 2-propanol that is not in your denaturant list.

so… where does this leave us? is propanol 2 safe for the PDMS layer? that would certainly free us (me) from all this IPA confusion.



2-propanol is isopropyl alcohol. Whoever responded wasn’t a chemist. It should be fine.



The take away is that IPA is fine for quickly clean the vats. Just don’t leave IPA in vat over extended time.



It is essential to bring some clarifications. IPA may be used, but just to wipe the vat and not to submerge the PDMS in it, as I did the first time when I cleaned the vat and had the awful result you see in the photo… There was most probably my error because I heard the suction noise for a while and didn’t stop the printer as I didn’t know all the consequences that this may have. This is part of my learning curve… Maybe there was also a small leveling problem too. Hard to say as this was a first try with a FTD resin that doesn’t come from Peopoly. More than that, the resin is white… and it is known to be harder to be printed. Anyways, IPA, if used in large quantities will make the PDMS layer become stickier to the build plate. At list this is my experience with it. Where I live, pure ethanol is hard to find as it is highly taxed. The next cleaning that I will make I will use a different alcohol. I found denatured alcohol that has 90% Ethanol, 4% Butylic and 2.5% IPA and hope the result will be different.

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yes, hopefully this thread will be useful for other people new to this. IPA for wipedowns, not for prolonged soaking. Ethanol is best.



(I’m purposely going to add various forms of these product names etc to hopefully help others searching. I didn’t find this thread/realize it was the same product due to a misplaced “-” ;-))

Ethanol heater fuel maybe a reasonable source of ethanol. Some product names are bioflame, bio-flame, bio ethanol, eco ethanol.

Some info from another thread I started about (what turned out to be) the same product.

“It should be okay as long as it does not contain thickeners or other evaporation control agents. However, that is for resin cleaning only. If it contains methanol, it can etch acrylic. Also, no guarantees or predictions on the effects on PDMS.”

In Canada, the list of allowed denaturants is here:

Methanol sounds to be the biggest “no-no” because it is an aggressive solvent of acrylic.

My summary of this thread and others is that:

  • IPA is safe for rinsing the acrylic and PDMS but not soaking(!)
  • ethanol is the safest for acrylic & PDMS, but is hard to source in many places
  • denaturants (stuff added to ethanol to stop people drinking it) can include methanol
  • methanol goes by many names. From wikipedia: Carbinol, Columbian spirits, Hydroxymethane, Methyl alcohol, Methyl hydrate, Methyl hydroxide, Methylic alcohol, Methylol, Pyroligneous spirit, Wood alcohol, Wood naphtha, Wood spirit
  • “bioethanol fuel” can be used to clean prints - but there’s a risk the denaturant could affect it
  • “bioethanol fuel” could be used to clean vats - but the denaturant might dissolve/damage the acrylic (methanol), or be an organic oil or something that messes up the PDMS layer
    • and the denaturant may be swapped from production run to production run, be mislabeled, etc, etc depending on local laws

So user beware: IPA is harsher, but easily available in pure form. Bio-ethanol/bio-fuel may be cheaper and the ethanol is less harsh, but the denaturant may have a big effect, and may not be clearly listed (or have a clear concentration marked.) You have to decide the risk, and stay on top of the product labelling.

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