Red shading on a model in the Preform software: Guide line or Definite print fail?

Hi all,

I have found the red shading of problem areas on models in the Preform software extremely valuable for detecting areas with issues, that I had overlooked during the modeling process.

I have also found times while examining the objects, I have not been able to track down what seems to be triggering the problem.

I would love to get more information reported back for these red shaded areas, but I will post that in the suggestions sub-forum.

I am curious if anyone has printed objects that have lightly shaded red areas, but appear to be following the rules. Any success?

What’s your feeling on how closely to follow the red shading guides when determining if you will print or not?



I have a similar doubt. Taking the model of Eiffel tower as example which I suppose it should be “OK” to print as formlabs has demonstrate the printout without any support or tilting. If I add support to it, different slope factors will have different red zone outcome (see attached file).  If I just look as the large red zone, I would say it cannot be printed (which is not true). So my question is: what is the typical slope factor I can use to reflect a more realistic situation of a successful print. Thanks.


hi Jimmy,

is that STL available online or can you share otherwise? i ask because i’ve seen other multi-part Eiffel towers but not the single one that Formlabs uses. maybe i’ve just missed it?



I’m actually using the Eiffel Tower model they pointed to in a different support message (it’s on Thingiverse) but it still shows up with red areas when I generate it. I’ve additionally had problems printing other models which printed fine on the Makerbot Replicator and don’t seem to have any errors in meshlab or netfabb, but will not print correctly (several have had large gaps, one did not print at all). Admittedly I’m just a newbie with Form1, but I have about a year’s experience with the Replicator and a whole folderful of models that printed fine with it, only a couple of them have printed without defects on the Form1 and/or do not show any red danger areas in PreForm.

I should add, I’m not complaining, I fully expected there to be a long learning curve just like was with the Replicator and before that the Cupcake, I just want to be educated.

OK great. can you point me to that message or the STL on Thingiverse? i’ve wanted to print that for a while but wasn’t sure which one it was.



In the videos I have seen the Eiffel Tower was always shown as a 2 part print model??

They may have printed more than one model type naturally . . . .

You know what would be nice is a few snaps of preform screen of the actual prints that formlabs produced.  Appreciate it may not be possible to share the .form file.

Would posting photo examples of failed prints help in the trouble shooting of these issues?

Corresponding with the red shading screen grabs?

It has to be an excellent idea Christopher.  Nothing less.  Please share away :slight_smile:

OK - this is what I have found - the “Slope Factor” in the Advanced Settings pull down has quite an effect on the “RED” zonesAlthough I did get a perfect 3DP part out of the default setting - the 0.23 was optimal  - go figure - someone a FormLabs needs to write up a definitive manual on ALL the Preform functionalities…

Best regards,


John (jay) H. Morewood
Owner / CTO / Rapid Prototyping Engineer
+1 408.839.4252

John, looking around at the prints from other users it does seem that there is a certain amount of alchemy involved in getting the settings right.  I have never done anything with a 3D printer (I only started drawing in 3D in April) so I have a bit of a bumpy ride ahead.  Still it’s

I take it the base is hollow for these support values to have an affect on the upper reaches of the design??


Thanks Jay. It gives an indication of slope factor setting on similar shape print out.

Other than just giving the red zone prediction, Does the slope factor has something to do on the curing algorithm such that I can save-print an object with smaller slope factor (maybe a drawback of longer print time)?



We are working on getting a bunch of articles posted to our support section. Here is a new one with summaries on all the Advanced Settings that might be useful:


Hi everyone,

we just posted a new article on “supportedness” coloring. In response to the original post, I would view this heat map as a guideline rather than a definite fail. It should be used in conjunction with manual orientation to give your part the greatest chance of printing successfully.


Thanks Jennifer and everyone, that’s really helpful!

I tested out this dino-in-egg model:

As you can see, the top was quite red but it came out fine.  I think this is due to the naturally strong geometry of a dinosaur egg.

I’d like to add a suggestion for the user-interface on shading the red areas in Preform. I missed a problem area on a print. It was an undercut step that turned into a tiny wisp of unsupported material when I tilted the part (I’ll try to get pics up later). The unattached, cured material made a mess of the rest of the print and left numerous thin sheets of cured resin in the tank.

It would be really cool to have a way to highlight the red areas (maybe an auto-rotate,pan,zoom function) so that users can spot them before printing. Adding a filter to the slice function to highlight areas that are poorly supported would be helpful too. Maybe if you could show the previous layer in a second color so that it’s more obvious how far a layer is hanging out in space, we could sort some of this stuff out more readily.

Like John Morewood posted, I’ve found “slope factor” to be the key parameter to change to get less areas to show up red. Not sure how it’s affecting the print necessarily… but it seems to be doing the job as my prints are coming out fine when I reduce that variable :slight_smile:

+1 to Andy!

The red is not necessarily a problem area.  It only means the area is not supported.

I recently ran several prints of the same figure.  In the first few, I used the ‘auto-orient’ which ended up causing really bad prints.  The pieces that were supported were great but there was a lot left unsupported.  I hand oriented the figure - doing my best to decide where the figure needed supports - and the end result was super, even though there was a lot of “red” in the drawing in Preform.

If you look at pictures from John Morewood’s spiral tower, forgetting about the red for a minute, you can tell that the top, though showing in red, should be pretty well supported by the base as it’s printed.

As someone mentioned, there is some magic to it.  I think the “auto-orient” function may not be ideal for complicated structures with a lot of arms and dangly parts.  You may be better off orienting it by hand and thinking about the way it’s printing and what needs support.  Then confirming that the generated support structures are in the right spots.