Does this look like a good bottle of Formlabs black resin?

Either i’m doing something wrong or this bottle of black resin is bizarrely off.
It foams during printing, even when completely devoid of bubbles before starting:

I can tie the supports in a knot (what?):

Prints have bizarre surfaces:

Top infill is full of pits and holes (DON’T tell me to tilt it, that’s not fixing the issue) ranging from tiny pockmarks:

… through missing chunks:

… to completely ruined surfaces:

Finally, bases have this film of cured resin hanging off their sides - here’s what a rinse of a few tiny parts resulted in:

The bottle was brand new, opened this week, received a few weeks ago from UK.
Lot number is: 20141106-01.
Vat was brand new.

Dear Formlabs, is this normal?

I would start with a mirror and galvo inspection and probably cleaning. If you haven’t done it yet there’s a good chance that’s all it is. Be sure to use pec-pads and IPA if you touch them. Resin issues is a possibility, but probably my second guess.

I agree with josh! My black resin has had similar issues as you are showing which didn’t result in any difference in the quality of the print. The only thing it didn’t do was flex that much. But honestly I didn’t really test that as my objects printed with black resin have mostly been more than 5mm thick so it wasn’t an issue.

Checked, nothing of consequence (beyond some tiny bits of dust i blew off).

Besides, it’s not like i’m getting holes through the whole print. Side faces are fine. Base topsides are fine. Anything at angles vertical enough not to expose the infill is fine. Infill is not fine. Consequently, horizontal faces and close to horizontal faces are not fine either. And by “not fine” i mean “completely uncured in spots”.

By way of proof, here’s a photo of the top surface of the base:

Here’s what large, purely vertical surfaces look like:

Here’s what large, oblique surfaces look like:

Now take a look at what the flat area (on the underside) looks like:

That botched area is right around the densest support cluster in that area. It was completely uncured.
In fact, even now, 10 hours later, it’s still uncured and not just tacky, but tar-like. I left it outside to see if it will finally harden.

By way of further proof this isn’t an issue with the optical path, here’s the area on the top side, immediately above it:

Quite clearly, any area that is mostly infill (surfaces close to horizontal) that are NOT cured in multiple passes (i.e. NOT base) are not getting cured enough. If there is enough perimeter to keep the integrity of the surface up, then there is no ill effects. If there isn’t, a tar-pit forms and surfaces are muddled.

The effect is not influenced by the area in which i print, BTW. It does change over time, though - it appears it’s the worst immediately after i agitate the resin (in the tank) with the spatula.

I’m now vaguely worried the tiny voids embedded under flat surfaces i’ve noticed in clear are the same issue, except at a weaker scale.

Note also that the layer striations are way more irregular and noticeable than what i’ve seen from most people’s photos (check the butterfly wing in the above photos, for example) as well as comparing directly to the sample rook from Formlabs (printed in black) i had lying around. My theory on why is - again, due to incompletely cured infill.

During a peel, a perimeter that’s well supported by the solidly cured infill will not move.
Conversely, a perimeter that’s not well supported, because the infill is soft, will slide slightly, making the layer-lines appear irregular and, thus, more noticeable.

I’m sure you’ve already done this, but if not it might be worth a try: tighten the camlock handle on the build platform. I did this about a quarter-turn, and my striations tightened up a loct.

Yup, the first thing i did, but thanks.
Haven’t tried the toothpick trick on the vat, though.

Anyhow, i did some comparison shots of the output i’m getting vs. the sample i got from Formlabs (before buying my Form1+). Firstly, let’s see them head-to head:

Doesn’t seem like much at a glance, right? Well, the devil is in the details (click to embiggen):

The real kicker is, that was the first sample i got from Formlabs (out of two). When i got this one, i complained about the surface quality and asked if that’s normal and they sent another one, in gray, that looked better - not just because gray is translucent, but because it truly was better (i tried lighting both at a very sharp angle and did some photos to check). In other words, Formlabs worst is better than what i’m getting.

Okay, now the final bit of insight. Take a look at the first few mm of my print up close:

What does that prove? Well, the double cured portion is the most regular and cleanest. The part that’s solid, and so has a bigger infill area, is a tiny bit worse. The thin, shell-like portions, with very little infill to keep the perimeters from sliding during a peel, are a total mess.

To me, that’s indicative of infill undercuring.
To test this hypothesis, i’m printing one Make Rook in black, but at the Castable setting. I know it will be overcured, but i want to test whether the finish (the regularity of layers in particular) will be better.

Update regarding this - the tacky area finally solidifed, leaving an even deeper pit:

Eyup, bumping up to castable fixes the infills.

It’s not 100% perfect (middle shot), but it’s better than on the black setting and closer to Formlabs sample. Note the letters are not the same size on the Formlabs rook and the Make rook - the difference in size is not an artifact of curing. Note, also, that the text on the castable setting is way more readable than on the black setting where some of the letters have chunks missing.

Focus on the “M” in “Make” to see the difference in layer striations between black and castable - i’d say that pretty much confirms the hypothesis undercuring of infill is causing perimeters sliding from layer to layer, creating rough banding.

Finally, here’s a head-to-head between my prints at black and castable settings:

Speaks for itself.

Would anyone from Formlabs care to comment?

Is my laser miscalibrated, does my bottle of black resin have too little photoactivator in it or is the software off with the exposure/speed settings for some reason?

@Ante_Vukorepa, it looks like there is something really weird going on here. Do that parts continue to ‘foam’ after printing?

Please submit a ticket to Formlabs support. They’ll work with you to figure out what happened and what we can do about it.

@Ante_Vukorepa even at castable the top blocks on the rook look really rough from some angles. As for overcuring resulting in better quality I’ve noticed this myself and wished I could control the portion of the print that is overcured, so on some prints I could do the whole print that way and others that might lose quality do non of it that way, but Fromlabs pretty much ignored the request. Ideally we would have full control of curing so we could tune our printers to get the best results and use the widest array of materials but that really isn’t likely to happen.

My guess is that castable doesn’t really increase curing/exposure on the perimeters, only on the infill, to ensure there are no voids / nastyness that might influence the burnout. At least that’s what the prints look like.

They don’t continue to foam - it only happens during a print. It’s like the agitation during the peel causes bubbling - you can even see some “soap bubble” membranes spanning between the supports here and there. The longer the resin sits in the vat, though, the less this seems to occur. I’ve purposefully left it sitting for a few days now and avoided stirring it and am now getting almost no bubbling (but other symptoms persist).

I’ll contact the support, i’m just wary of having to wade through the “did you clean the mirror”, “did you really clean the mirror”, “did you shake the bottle” stuff. Can i just point them to this thread?

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I’ve submitted a support request, but haven’t received any indication it was submitted.
It just redirected me to

Not sure if that’s normal or not.

Edit: Nevermind, scratch that. Fished a confirmation email out of the spam folder.

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