New LT Tank question

I received my new LT tank, I know the standard tank it’s not recommended to leave the resin in tank for months as it cause leak, How about the new LT tank, Assume there is print every 2 weeks once how long is the maximum I can use it


I don’t know about the LT tank, but I never heard anything about not leaving resin in a tank.

Since I use different resins, I swap out tanks quite often and store them with resin still in them until I need to use them again. The only thing that happens is the resin pigment settles, so it needs to be stirred with a spatula before use.

You will be interested in this then :

I was as surprised as you probably will be after reading this. It is officially advised to not keep resin in standard tanks for more than 1 month, and 2 months for LT tanks. This seems like a sentence that has been placed there in order to avoid having to pay for catastrophic tank leaks in the printer.

Needless to say, my several standard tanks do last much more than 1 months and I certainly do not empty them when I do not plan on using one of them for more that that amount of time, it would completely destroy the workflow that makes the Form2 so easy to use.

If there is really a risk of damaging the PDMS or anything else, then what about a tank that is used once or twice a week for very small prints such that the tank lasts more than 2 months ? This use case would be pretty normal.

According to FL and my general understanding, the above is quite accurate and I have noticed with my last standard tank that the PDMS is slowly coming undone. I can see where the major headache would come in after a month of idle time. Mine doesn’t sit more than about a week between prints.

Becuase of this thread, I went and looked at some of my tanks that have been stored in a closet, stirred and mixed the resin and inspected the PDMS around the edges to see if it’s coming off or not, as well as the general transparency of it.

Tank #1: Clear, sitting for about 2 months. No signs of degradation
Tank #2 ALW Beige sitting for 3 months. No signs
Tank #3 Grey v2 Sitting for 8+ months. Resin expired a long time ago, dumped, PDMS still OK
Tank #4 Black V3 At least 1 year old. PDMS looks OK, I’m not sure about the resin. I’ll try a small print

Current Tank in printer: ALW Beige+Black grey mix, about 3 weeks since the last print. No issues.

I should also note that all these tanks have been recoated by me using Sylgard. None of them have the original PDMS. These are all Form 1+ tanks

I don’t see why using a tank to print is any different than keeping it stored. As long as there is resin inside the tank it should be degrading it (or more likely degrading the adhesive keeping things sealed). Is there something that settles to the bottom over time other than pigment that would degrade it faster?

I have had my High Temp material, and Dental SG eat through adhesive on resin tank and leak tons. I keep all my tanks in a larger plastic bin just in case this type of thing happens so it wasn’t a big problem. I have not seen degradation with standard resins though.

The LT tanks have a pretty different construction, I have not seen or heard of any official statement regarding this potential issue.

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You keep mentioning adhesive. There is no adhesive. When coating a new tank, the PDMS liquid is poured straight into the vat and then left to cure. It simply fills every nook and cranny, and as it cures it sticks to the tank walls.

I’ve had one instance where the PDMS peeled in one corner before, and that was because the tank wans’t cleaned properly in that area, so the PDMS didn’t stick there, leading to the resin to get underneath it. But that was my mistake, a “manufacturing flaw” if you will.

AS for the resin reacting with the PDMS, I’m sure there are resins that do, more so than others, but in general, it’s the curing process that does the damage. Most resins sitting in a tank, in their liquid form, and in a box, without any light to polymerize them, should not negatively impact the PDMS surface.

Moreover, the acrylic window at the bottom of the tank is glued in place, and there shouldn’t be any gaps through which ANY liquid should leak. So even if the PDMS layer was to lift or even completely disintegrate, the tanks should be able to hold the resin without leaking.

If it leaks, then the tank was either defective from manufacture, or it got physically damaged during use.

You mention there is no adhesive and then you mention that there is glue on the acrylic window. This is the adhesive that I am referring to.

Yes, but the only way for the resin to get to that is for the PDMS to be destroyed.

Nevertheless, I’m not sure what they use on the Form2 tanks, but the glue used on the Form 1+, is actually some form of acetone (I use something similar called Weld-on), it literally melts the surfaces together, that fused bond is as strong as the actual plastic, because it IS plastic.

Because the 2 parts are fused at a molecular level, there’s no substance that would “unfuse” it. If something leaked through the tank, then that was a manufacturing flaw or a cracked/damaged area.

This is exactly why I find the 1 & 2 months recommendations to be strange, and also why I think it’s a liability thing more than an actual rule that Formlabs would like us to follow… This is only my opinion though and I’m sure Formlabs will no be able to confirm this.

I certainly will continue to store my full tanks for more than a month…

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So i had a standard tank with clear in it that was less than 2 months old that stared to leak. FL replaces the tank without questions and also gave me a coupon for a discount on my next resin order. But they mentioned that you should not store resin in that tanks.

So here is how my failure went. The PDMS layer started to separate, it was undamaged but resin started to seep under the sides. This was evident by bubbles under the PDMS layer between it and the acrylic tank bottom. I ignored this thinking it was the “clouding” that is mentioned on used tanks. But you could push these bubbles around a bit with a spatula. About a week after i noticed the bubble i noticed resin on the top of the printer. It was slowly coming from the bottom of the tank. You could also see cracking in the area where the optics window is glued to the orange tank. It appears the resin attacks this joint and causes it to fail rather quickly.

Best practice is probably not to store tanks on the printer for more than a day or so. that way if you have a leak it will not end up in the printer.