Stored tank melted into goo, then leaked Black V4 resin!

I had a tank, partially filled with black v4 resin that I’d swapped for my Grey, which I’m currently using.
I put the tank back into its box, with the lid on, and put it in a cool, dark and dry place.
A few weeks went by, and was doing a major cleaning of my work area, when I noticed that box was stuck to the floor!

The tank had failed, and leaked black resin all over the box, which then soaked through onto my hardwood floors! Thankfully, because it was dark where I’d stored it, nothing had cured.

Most curious to me, was that the “glass” portion of the tank was completely flexible goo now. More like melted cellophane or thin latex than glass or plastic. There was no heat, light or other forces besides gravity and the contained black resin acting on the tank. Why such an extreme failure?

Is this common? Is this something I have to worry about with my tank in the machine? Will FormLabs replace the tank & resin?

You can find several reports on this forum about this issue.

Don’t store resin for longer periods in a tank. Something in the resin causes the PDMS to swell and get separated from the tank and then the resin will attack the acrylic window and glue. It is common for tanks that sit for several weeks or months without stirring the resin.

It happened to several tanks of mine and yeah, creates a big mess. You could try to contact support but that never yielded any satisfying results. It’s just ‘bad luck’.

If I print constantly and the wiper wipes the resin I will not have this problem?
I have had my tank for about a month , a bout 1.2 liters have been through it already

So far I have only seen it happen with tanks that had resin in it for several weeks without being used. I’m sure these new LT tanks don’t suffer from it and can highly recommend those if you don’t use some resins a lot.

This was not an issue with the V1 and V2 resins. I started having issues with the V3 and V4.

Personally I don’t like the V3/4 resins. They seem to have less detail for me and are a bit harder to print with (more failures than in the past)

If I could get V2 resins that’s all I’d buy for normal prints.


I never had issues with that before, I’ve had trays with resins sitting for months with no problems, though that was the older resins.

I have a little bit of clear v2 left in one my tanks that is well over a year old that still works and hasn’t dissolved the tank.

Did you need to call the EPA to declare it a super fund spot or are they no longer doing that? Do we still have an EPA?

Same here. Black and Clear are rarely used and stored for months without issues yet.

@ScoobyDoofus : The fact that the (acrylic ?) window had “melted” is very strange, do you store any other chemical in the same enclosure as the tanks ? Like acetone, white gas, white spirit or something ?

I wonder if @ScoobyDoofus is possibly referring to the PDMS, which would fit the description well. I’ve only seen the acrylic crack.

It looks as if bubbles are slowly forming under the PDMS next to the acrylic window. These bubbles grow and grow until a point where they pop open through the side of the tank. That’s the moment where resin comes under the PDMS and starts attacking the glue and acrylic window. This could be an interaction between peeling force of large parts and outgassing.

Not sure what is in the formulation of the newer resins that react with either the acrylic or even worse the silicone pdms but I would be weary of using something that potent.

Not sure how much has changed in tank design in general with the F2’s but on the F1 tanks there are considerable design flaws whether it is material choice, wall thickness and general construction where the clear window is held by glue and forces push in direction of assembly which makes the glue line incredibly critical. Often after a couple of liters they have catastrophic failures. Understandably because acrylic sheets vary in thickness by batch and have horribly loose thickness tolerances it makes it difficult to design around and keep the pdms volume precise.

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