Trouble Shooting – Part cured resin (jello) after every print

@Steve_Johnstone what I meant was that you’re possibly conflating two separate issues - cold resin causing bubbling/hollows, and flare causing bad surfacing and flaking.

I don’t see that you can conclude cold resin makes flare issues worse is my point. My contention is that cold resin is likely sufficient to cause bubbling/hollows on its own - even in a machine that had a perfect spot without any flare at all.

@KevinHolmes I fully understand where you are coming from, but that doesn’t explain why the major faults never once appeared on the hinge or peal sides surfaces of any print I’ve done to date. For your argument to be true I would have at some point seen bubbling / hollows throughout the prints, not just concentrated on the back surfaces, facing the hinge.

@Steve_Johnstone but how can bubbling/hollows have a “side” or “surface”? - those parts are only 2mm thick - the bubbles must be in the middle of the part.

If your point is that the bubbles appeared only in the y-axis (or x? not clear from your pics above) oriented slab-features and not the in the x-axis oriented slabs, then that’s an interesting point - which I hadn’t picked up on before…

But I would argue that it’s still not connected to flare, and is most likely caused by the direction of the peel - and that if the F1 peeled in the y-axis instead, the bubbles would switch axis - independantly of your flare orientation.

I guess I could experiment - since I’ve seen that kind of bubbling in the past and didn’t understand why. At some point though I switched to keeping the lab heated, so given your results I strongly suspect that my bubbling was also due to cold resin. I could turn off the lab heating again - see if I got bubbles, then print again with flare oriented in the Y axis instead - and see if the bubbling changed. Lots to do at the moment though - not sure if I’ll have time.

@Steve_Johnstone Can you please post pictures of those same prints after washing.

For clarification. The prints I did of the same file on our now defunct thread were done at 20.9C. The fume hood I run the printer in and that room have good temp control because of the other stuff done in that space.

The solid parts e.g. the rook have the major bubble flaws on the rear facing surface. The last print I tried before bringing the printer in doors was a solid version of the cockpit canopy that failed at about 50%. Again the the major bubble defects were on the rearward face.

Solid Canopy, 0.1mm LH, clear v1 resin

Rear / Hinge Side

Rear Face

Front Face

@EvanFoss, I have now printed the test cross at the other two layer heights 0.05mm & 0.025mm. It’s my opinion that the rear facing surfaces get progressively worse the as the layer height is reduced. To me this make perfect sense as at 0.05mm the laser flare covers the same patch of resin twice a many time as it does at 0.1mm. At 0.025mm, this increase too 4 time… I hope that makes sense :smile:

I agree with reported comments from Formlabs support that orientating the print at 45 degrees will improve the surface quality as the laser flare path won’t cover the same patch of resin as many time. But from my experience with other parts printed since, you are still get part cured resin in your tank that can only be filtered out. The test piece however, was design and orientated to purposely to test @KevinHolmes theory, which I think it does very well.

Grey resin is probably a better colour for these tests as its quite hard to photograph clear parts.

Test Prints

Printed at 0.1mm Layer height, clear v1 resin

Printed at 0.05mm Layer height, clear v1 resin

Printed at 0.025mm Layer height, clear v1 resin

@Steve_Johnstone ok - that rook bubbling is interesting. So what’s the theory; that flaking on the flare side can act as traps for air bubbles?

I think it’s obvious now why cold resin can cause bubbles/hollow parts - cold resin is more viscous, and once past printing the base and into printing the part proper when we have fast peel cycles - if the resin is viscous enough (eg when cold) then air will be sucked under the part during the peel cycle creating bubbles than can get trapped under the in-progress part - preventing any resin cure at those points.

The open question for me is whether flare and cold resin interact to cause a greater problem - and going by your rook print, perhaps it does. I’m going to run some experiments myself now.

Note - I suspect the resin level in the tank can also contribute to bubbling/hollow problems - ie a half full vat will be more likely to generate bubbles than a full one.

Well I couldn’t reproduce the bubbled parts problem by reducing the temp - although I did only try a couple of times. I turned off the heating left the window open over night. It was 12degC in the morning - which produced one complete failure. Then after shutting window and warming to 14deg - I managed to get a complete print - but no bubbles in the parts.

I still believe that cold resin causes bubbling though. I did see a lot of it in the past when I wasn’t heating the lab. Also presumably it’s made worse by bad flare - as shown in @Steve_Johnstone’s rook print above, but I don’t have time to look into it further.

I did notice however that air bubbles were being created during the peel - and also that my bases were flaky - showing layers of uncured resin in the base.

So it seems cold resin is the cause there too - not the platform height as I thought previously - which makes sense. Because the resin was so viscous I could hear and see the “thunk” of separation when peeling the base layers - and it seems that suctions forces are so great on the peel cycle with cold viscous resin, that base layers can be partially separated.

@Steve_Johnstone, @KevinHolmes,

Unfortunately i have encountered similar problems with my latest prints and I don’t have a solution for it either. Hopefully we’ll be able to fix this together because it’s affecting my prints in a bad way as well.

Like Steve’s print. I have rough surfaces at the front and back side of the print. Hinge and other side are perfect.

As far as I can conclude it has nothing to do with the laser as this is my laser:

I have printed the same part over and over again, using the same angle and spot to print with no good results as of now.

My printer operates in a 21 degrees Celcius room, and my cabin with all the resins in it is actually placed against the heating so the cabin is a few degrees warmer. Therefore, temperature does not seem to be the issue. A cold environment might make the print worse, but it’s not the cause.

I’ve tried printing the print with 0.2mm layers and 0.1mm layers with no difference in finish. Both were rough.
Cleaned the mirror with IPA and pec pads and printed again. No difference.
Strained the resin and printed again. No difference.

I have no idea what I can do next to find out why the print has such a rough finish.

Thing I noticed is when washing the part with warm/hot water between the 2 IPA baths, the rough spots seem to be highlighted in white… No idea how that helps. Hopefully we’ll find a solution :frowning:

@Alex_Vermeer if you have rough surfaces on one side of your parts near the hinge side - then that sounds very much like laser flare. I don’t think that laser spot photo is really any evidence that your laser spot is fine.

It is very difficult to take photos of the spot through the cover - and there are so many factors that can mean you miss detail; the camera exposure, the thickness of the paper, etc, etc,…

Moreoever - for there to be a completely separate issue that causes those same specific symptoms; ie rough surfaces on one side that are worse near the hinge, seems unlikely to me - that is, if you really do have exactly those symptoms.

Do you have a lot of flaking on the rough surface side as well?

Have you tried my test cross pieces? Form1+ laser flare issues illustrated - pics and video they illustrate the symptoms really well.

@Alex_Vermeer, I agree.

To get a good picture of your laser spot I put together a paper template and some video instructions you may want to try -LINK

I would defiantly print @KevinHolmes cross test pieces as well. The lower the layer heights are, the more evident the problem should be. If possible take some photos of the printed parts still on the build plate, before washing, then after once they have dried etc.

@Steve_Johnstone, Thanks for the PDF. I’ve taken another photo without the cover and it seems you are both right (unfortunately)…

@KevinHolmes, I do have small flakes on the rough surface sides of the part. I shall print your cross pieces in .1mm to see how they come out.

Thanks for the help and I will get back to you soon!

@Alex_Vermeer a better test is 50 micron - the smaller the layer height the more obvious the symptoms.

Also if you can, don’t use clear - since it’s hard to see which side defects on are on.

Glad you replied so quickly! I canceled my clear print and will print in Grey with .05mm


I think the calibration sheet for the laser should have marks like on a reticle so that you can more easily measure from photos.

  1. Print the calibration sheet.
  2. Measure the width or height of the box on the sheet you printed.
  3. Display any photo of a laser test that uses the same sheet.
  4. Measure the same dimension on the box as seen in the photo, that you measured on the printed sheet.
  5. Compute the ratio of the chosen box dimension as measured on your printout to the same dimension seen in the photo.
  6. This is a scaling factor.

Measure any aspect of the laser flare as seen in the photo and multiply by the scaling factor and that’s the actual size of the feature you’re looking at! (well, with some provisos on accuracy which will be a function of camera lens induced image distortion, which depends a lot on the camera used).

Well, here’s my result of the cross test print. Unfortunately the cross on the PEEL SIDE failed after a couple hundred layers. But I let the print finish because that might be caused by an issue related to the laser flare??

Here we go:


(this is the front side of the broken part (on the peel side)


My apologies for the many photo’s. Normally I would have captured both in one single picture, however, since on part failed I decided to take seperate photo’s as this might help.

Looking forward to your comments!


P.s. This seems to be a common issue lately…

@Alex_Vermeer hmmm - certainly not obviously drastic flaking that I can see - but you do have peeling bases and I think I see bubbles in those parts? and the one that failed - it looks bad - a bit swiss-cheezy?

I used to get those same issues - but I’ve changed two things (edit - actually 3) that I can think of since then - lowered the build platform, and heated my lab. Previously I thought it was due to the build platform height, but with @Steve_Johnstone results I’m thinking those are typical symptoms of resin that’s too viscous - it makes sense, the extra suction of more viscous resin causes layer separation in the bases, and sucks bubbles under the part during peel.

You say your resin is kept against the heating - and the room is 21degC - if you’re certain, perhaps its still viscous resin, but not because it’s cold.

How old is it your resin? I had to wait 6 months for my F1+ upgrade (even though I ordered it on the first day!) and when I tried to use my remaining resin - parts pretty much all came out swiss cheezy or total failures. New resin improved things a lot, and then things improved again when I put the heating on. I still get heavy flaking and solid corrugations on flare oriented faces near the hinge - but no bubbling.

I totally agree will everything @KevinHolmes says above & your results look very similar to mine.

I would be really interested in how fresh you resin is and if you filter between prints.

@KevinHolmes and @Steve_Johnstone,

I wouldn’t say it’s the temperature as that is regulated and it shouldn’t drop below 20 degrees Celcius. However, my grey resin was purchased on 30 September and delivered on 20 October. This means the resin is between 3-4 months old (not taking into account the amount of time it’s sitting in the Formlabs warehouse. Therefore, this could be an issue.

Unfortanately I don’t think it can be proved that this is the proper reason for these kind of bubbles/scars as I have the same issue with my Clear resin V2 which I purchased on 19 November and was shipped to me a week later (+/- 2 months old). If this would already be “old” resin, then I have a problem as I still have two unopened clear resin bottles as I ordered three together.

I can print the crosses in clear resin as well to show resemblances/differences to ensure that it’s not the age of the resin that is the case.

I shall not lower the build platform as of yet, to check one difference at a time. Otherwise we’ll never be able to pinpoint different symptoms.

I do not filter my resin often (enough). I do use a comb to find small cured parts, however, most of the times I cannot find any cured parts in my resin. I have filtered my clear resin a few days ago when these problems started to occur, but that didn’t have any noticable effect.