Form 2 Optical Window

Hi Guys,

Have some questions about what I’m seeing on my Form 2 optical window. Just recently (last 3 prints) we’ve been getting bad results & the last print ended in a failure. Please see the pictures below.

As you can see there’s a gasket coming loose & some “discoloration” on the window itself. If you look closely on the 2nd picture, you can see some “sparkles” that only show up under light. We tried following the steps to clean the window, but the discolorations remained. I am wondering if they are internal/permanent at this point. I’m not sure if the gasket coming loose would cause an issue either. If it doesn’t get in the way of the laser, I could see it being OK, but I’m not an expert hence this post.

Any advice? Is this a replacement unit?


I run a farm of 4 Form 2 machines, and have had great results running with that window removed entirely. Makes it trivial to clean the galvos and mirror as well.

First, I’m not a pro, but this is my learning experience:

You can buy a new window. 2-3 years ago when I was new to Form2 we had issues with bad prints and a bad laser. Form Labs blamed the window and tried to suggest I may have spilt resin (which wasn’t true) and told me to clean it. The trouble is that gasket bulges out with time (even from new) and has gluey gunge that slowly seeps onto the window. It dissolves in the IPA and you just smear it around when following their cleaning instructions and the window never gets so you feel like it’s really clean. HOWEVER, when they send me new ones (I’ve had maybe 3) they arrive REALLY dirty. You can carefully blow them off with air. But it turned out that (other than a bad laser) the problem really had nothing to do with the window at all, it was just the BLACK resin didn’t perform well. For the longest time I thought BLACK just didn’t perform to spec (all the other’s I tried were great) but once we started cleaning with TPM instead of IPA we soon found that BLACK was working much better than previously thought, the TPM was clearing out trapped resin far better than IPA. (We print very detailed small parts with lots of nooks and crannies).

The windows seem to become discolored with use, I don’t think that’s affected the print quality.


I have only seen the discoloration on the back side of this glass, and it can be cleaned off. Its just tedious. The last time I took mine out it looked like someone had sneezed on it. After cleaning it my print quality improved a lot. The way the FormLabs guides tells you to do it works pretty well but i have run into issues using my fingers and keeping constant pressure. Creating smear marks. I threw together this tool to use with the PEC pads a while ago and it makes life much easier.Glass Tool Print File.form (948.8 KB)

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