Form 3 print looks like it has cake icing on it

We have had our Form 3 for about a month now, and are generally happy with it. I pulled a print this morning that was basically an elongated cube. It came out with a texture on one side that looked kind of like it was cake icing! Does anyone know what would cause this to happen on a print?
[Image Here](IMG-4320)

How big is that model? Have you printed it before, without the unwanted artifacts? Are they present only on that side of the print?

You could try increasing the size and density of supports, play with the orientation, make sure the optical path is clean, and that the resin is fresh and mixed.

Or it could potentially be a case of the known “ripple” effect suffered by the Form 3 (perusing the Form 3 section will pull up other examples, like here and here). Either way, I’d open a ticket with Formlabs Support.

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I find this type of thing happens most frequently because of one or more of these things:

  1. Old resin
  2. Print was started before resin was up to temperature
  3. Resin has lots of air bubbles in the tank.

that defect looks very similar to what some of us have seen with the Form3.What resolution were you printing at.have you had successful prints of this model on the form3 before?

I have the same issues. I am brand new to resin printing so I could be making a lot of mistakes. Up to this point I used the “autoprint” feature on the software since I don’t really know what I am doing yet.

BUT, all my parts printed with the white resin (FLGPWH04) have ~ 0.25 mm extra layer…just like icing. I am following the suggestions for both the wash settings as well as the curing settings.

Is this just something I have to live with and design around?

This was printed at 50um. I didn’t reprint it because that particular face was not important. I was just wondering why it would happen so I could maybe prevent it in the future.

You mentioned old resin. This was printed after replacing the resin cartridge for the first time. Should I be dumping out the resin from the tank and cleaning it periodically?

Hi rkagerer,
The part was about 76mm in length. I did not reprint it, but it does look like a similar artifact that appears in parts that have the “ripple” effect. Thanks for the links!

I think it had to do with the age of the resin that was in the cartridge as it was expired and had not been used in a long time.

As long as I keep the tank covered then I do not worry about the age of the resin in it. And even when I change to a new tank because an old tank is worn out then I pour the resin from the old tank into the new one.

Thank you Matt!
How often do you replace the tank on the Form 3? We have only had ours for just over a month.

I am not sure exactly how often but not too many times.

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I’m printing mainly thin flat shells on my Form3 and I have seen many times exactly the same effect. I can tell you that it’s not old resin, not bubbles and not low temperature. What I found is a process I call “parasitic curing of residual resin” - it occurs when I do printing of flat surfaces oriented close to horizontal, which are facing to the build plate (the side not facing to the build plate is not affected by this effect). It’s parasitic resin curing - when the resin stays for longer on detail surface and when printing is in progress, the diffused UV light from the laser spot cures partially the residual resin in vicinity. Having supports in the area worsen the effect as supports have capilar effects and slow down the resin flowing out (resin is trapped for longer).

The scenario of the effect is like this:

  1. During the printing, if the resin can’t flow out from the area and stays longer “unwashed” from new resin from the tank, it becomes “sensibilised” and with the time cured by the parasitic UV light. Once the resin is semi-cured its viscosity decreases and becomes more difficult to flow out from the area and the process accelerates

  2. Large horizontal areas facing to build plate can form structures similar to “vane” and hold for longer the resin. I noticed that if the area has supports in it, or ends with a row of supports - the effect increases (capilar effects hold for longer the resin trapped in the area and extend the parasitic UV light exposure time).

  3. You may noticed that the artefacts have orientation which follows the path of rein flow out, areas that prevent flow out get covered with thicker layer of parasitically cured resin (parasitic cured resin layer is thicker behind the supports, in “resin flow out” direction).

Fortunately there is a simple solution for the effect - changing the detail orientation and trying to minimise the supports in the area can completely remove it. For example if you print the same detail and the affected surface has 60-70 deg angle to the build plate (detail is closer to vertical position) you may not see any problems on the surface. Well, as Form3 print time depends significantly on the height of the detail, changing the detail orientation will make the printing much longer (maybe 2 - 3x longer).

It would be good if the software can detect these “vane” conditions just like “caps” and unsupported areas and warn the user. Users are tempted to speed up the printing and they try to orient big flat areas parallel to build plate to decrease the total time, unfortunately this is affecting dramatically the print quality in some places because of the described effect.


Would this be less of a problem with resins with a higher pigment content like black or white?

Hi billb,
Good point!
I think there are two factors affecting directly the effect:

  1. Definitely the resin matters. If you asked yourself why the white resin can be printed only to 50um resolution where transparent and black to 25um - maybe one of the reasons is that parasitic curing of white resin is worse compared to others. Instead of curing single spots of 25um in size the light cures also partially the resin around and the effective resolution becomes 50um. . As the effect is not officially described and confirmed - nobody did experiments in this area. Any changes in the viscosity, UV absorption and light diffusing have impact on this effect. I’m using white resin so the effect is definitely existing for white resin, can’t say anything about other resins as I don’t use them.

  2. Print resolution - having higher resolution means the printer will spend more time to cure the layers and hence more time to parasitically cure the residual resin. I didn’t try this (the resin is pretty expensive to do such experiments on my own without any financing) but I guess that the effect will be less visible for low resolution prints and more visible for highest resolution prints. Ironically you can get worse results and appearance by increasing the resolution if you don’t take in account this effect.

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