Cured residue in resin tank sticks to new prints

HI. I have been using the Form1+ for some time now and i have run into a problem that continues to haunt me. Small “strings” and other particles will cure in the resin tank and stick to my prints. Just changed the platform, and resin tank + resin, cleaned mirror and laser with pressured air. Worked for the first couple of prints, but now i am having the same problem. Anyone know how to fix this? The small “scabs” can be picked off by using the tweezers, but i would rather not mess with my prints right after washing since i might destroy the microstructures.

I don’t think these are cured parts from the resin tank. This is just by not washing them in IPA properly!. I’ve had the same finish with some of my prints, but I could wash them off. Sometimes you need to use your finger (wearing the black glove) to just wipe them of when they are dipped in the IPA.

I usually shake them in IPA for 2min then let them soak for 10min then i repeat the same procedure in the 2nd “washtub”. Have tried wiping them, but after the soak it seems that i am able to not only wipe off the residue but also part of the structure.

Wouldn’t that mean that the print hasn’t cured properly yet? When I take my print of the build platform, I cannot wipe of anything else than residu…

Hmm, so that might indicate a laser problem? I usually have to let my prints dry over night before handling them since i am able to smear the outer layer by touching it

Or possibly oversatured IPA?

well it’s kind of hard to tell. Can’t you do another tets print of the same object, but smaller, and see what happens if you rinse it properly and use your finger to wipe away extra resin?

I had a few similar issues a while back. I did consider using a windscreen washer pump or similar and make a flowing IPA tank to “force” the IPA through the prints.

Here’s a question, when did you last filter your IPA? Passing it through a 125 micron mesh helped me refresh it and get rid of a lot of these small pieces.

Hey. Thanks for the replies. Been a while since i replaced the IPA and havent filtered it so that might help. Had a problem finding paint strainers in DK, but i got my hands on some. I will try to filter both the IPA and the resin and do some new prints. Could it be a problem that i am using technical grade IPA (around 96%) instead of the 90% recommended? I imagine some problems could occur if the resin is soluble in IPA.

90% or 96% isn’t the issue. I use 99.9% IPA to wash my prints and haven’t noticed anything desolving. Not even over time. Filtering the IPA is a very good idea though. When I have washed several prints I can see cured resin floating in the IPA. Especially when washing any other print than black you notice immediately that the cured resin sticks to the prints. However it’s only a few flakes for me. Yours are covered. So yes. Filtering the IPA once every 10 washes is highly recommended! Perhaps that is the starting point of your issue.

Hi again. Thanks for the advice. I just took new prints off the printer and they are covered in flakes even before the IPA wash. So even if filtering the IPA could help the is an issue in the resin as well

Do you have a photo’s? Or are they just similar to your original post?

Very similar to the original photos. I also see them when printing from another tank using black resin

Silly question, but have you cleaned all the mirrors including Galvo with 99% IPA and PEC pads per Formlabs instructions? I had this to until I regularly clean all, filter my resin and air my tanks as procedure every time I change resin or run a good few prints.

I have cleaned the mirrors (not sure what you mean with Galvo) using compressed air with a long twisted hose and lint-free lab wipes. I just spotted the new “cleaning the mirror” post though. I will give it a shot. What do you mean with airing the tank?

These are the galvo mirrors:

They are the small mirrors on the unit with the laser.

These 2 tiny galvo mirrors must be cleaned with care! There is a square mirror on that block as well which is about 3x3cm and you should clean the inside of that mirror as well!

Be sure to open a ticket and ask for exact cleaning instructions to ensure that you don’t void your warranty!

Perfect. Thanks a lot. My printer is in a fumehood which means a lot of air circulation which leads to a good amount of dust everywhere. Ill open a ticket and get some guidance.

@Ruune_Larsen, the printer does not need to be ventilated, so you can remove it from the fume hood if you think that this is a source of dust.

Hope this helps!

Would love to, the problem is i am working for a big company and the guy who does the safety evaluations went a bit overboard. Put a request in for reviewing the safety, but it is not happening any time soon so im stuck in the fume hood for now.

maybe don’t turn on the hood?

I also noticed residue left on the large mirror when I used a can of compressed air on it that had to be cleaned off