Fine splatter/droplets on inside of cover (and optical window?)


Hi all. We’ve noticed some fine speckling/splatter on the inside of both of our Form2 machines covers. We notice these mostly on the left and front inside surfaces (when facing the front of the machine), and very little on the right inside surface. See pics. I found a couple others posts about this that were mostly concerned with how to clean it. My question is that we recently had to replace the optical windows on our machines due to similar speckling/splatter so I’m wondering if the same source is causing both (cover and window) splatter. FWIW the machine is only open long enough to remove or replace the build plate, change the resin tray, etc.

One theory I read was that these might be caused by the popping of air bubbles in the resin (pushed over by the wiper arm). That seems like a feasible explanation. I’m not overly concerned about the splatter on the cover itself, but splatter on the optical window is definitely cause for concern because it will effect print quality.

Has anyone else seen or experienced this? And, any ideas on how to prevent it or at the very least prevent the optical window from getting fouled? Thanks for any ideas.


Hey there @humangear!

Thanks so much for taking the time to post! I’m sorry you’re having a little trouble with resin speckles! Definitely not what we want to see.

Can you tell me if this seemed to occur after 1 specific print, or whether it’s accumulating more slowly over time? Typically we’ll see results like this if the wiper has something to run into in the tank.

I think your theory of the bubbles is a really interesting one, but stuff popping in that manner wouldn’t be able to get on the Optical Window like that as far as I know.

I agree with you though, we don’t want you printing on an optical window that looks like that! Please reach out to our support team at the link below and we’d be more than happy to help you get that all taken care of.


Dkirch - thanks for your response.
It’s hard to know when the speckling started and how quickly it appeared. We just noticed it recently so I’m not sure if it happened just after one print or after a longer period. I can’t fathom how all of that would happen in one print so I’m guessing it’s a more gradual process. It does seem interesting that the speckling is only on the left hand side and front, but not the right.
But, I hear you that it would be really hard to get the splatter on the optical window itself. I’m not sure how that can happen if the tray is directly overhead 99.9% of the time (only exposed on rare tray changes). I might think it was a build gone bad or something, but we have seen this on both of our machines so it’s hard to write it off as a one-off event.
Regardless, I did contact support some weeks ago and they were prompt in responding. They asked me to try some cleaning but no amount of rubbing would get the speckling off the window (I sent some microscope pics of the droplets to her). Support sent me two replacement windows, and we ordered two additional ones to have as backup.
I’m a little surprised no one else has responded to this message - I would’ve thought if we experienced it others would have, too. Anyway, if you ever learn more about what might be causing this issue please let me know. Thanks.


Do you always remove the build platform every time you remove a tank?


Billb - No, we leave the build platform in place when we remove a tank. But we clean the build platform after every build so even though it’s over the tank/optical window when we remove the tank there wouldn’t be any resin on the platform to drip down. Is that what you were thinking might be happening, or was there a different notion with your question? Thanks.


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