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Problem with Rigid 10K Surface Cracking

I am printing with the Rigid 10K resin from Formlabs and have been experiencing some unfavorable surface quality issues. I am using the form wash and form cure devices for post processing. The skin cracking (as seen below) occurs during the recommended UV curing process.

The cracking only occurs on the white film that forms after air-drying and does not penetrate deeper. I have found that this issue is isolated to parts printed with faces parallel to the build plate. This can be mitigated by printing on an angle but I would prefer to find the root cause of the issue rather than limiting the options for part orientation.

Has anyone else experienced this with the Rigid 10K resin? It has happened with multiple lots of this resin and I am not sure of an easy fix. I look forward to reading the community response.

Printed hundred of parts with Rigid 10k both on a Form 3 and Form 3L and never saw that happening, not even after months after the parts have been printed. The white part does scratch easily but I never saw a single crack.

Some ideas:

  • Completely dry the parts. I usually do this with an electric air compressor which takes a minute or so.
  • Do the drying after the first 10 minutes wash AND after the second 10 minutes wash.
  • If the above is what you’re doing or it doesn’t help, try lowering the cure temperate by 10 degrees. At least on my case, back when I used the Form Cure, I had to do this to avoid warping (different issue, but still an issue) but now with the Form Cure L I don’t have to.
  • Another thing you can try is before each drying and even before the first wash, clean the surface with a nitrile glove (the ones you’re probably using so a finger can do the trick) to remove any excess. I would do this in steps (first before the first wash and see how that worked and only repeat that and add the next step if it didn’t work, and so on).

That’s all I can think of at the moment.
Cracking might suggest some air stuck between layers (that white coating is super fragile) that might crack when exposed to heating when curing but that’s just a theory.

were you putting the parts in the form cure immediately from a cold start or did you let it come up the temperature first?

I believe it’s recommended that you put them in cold and let them slowly warm up and cure

Thank you for the reply. I have been sure to fully dry the parts prior to UV curing but will put more emphasis on drying between wash cycles and will try removing as much of the coating as possible with the nitrile gloves. Lowering the cure temperature is worth looking trying but I don’t want to sacrifice the mechanical properties of the part to do so.

This is a good point, however I have already been starting the pre-heat with parts on the turn table so that can be ruled out.