Pouring resin out to extend tank lifetime?


Hoping that someone from Formlabs can chime in…maybe @DKirch or @JenniferMilne?

So we all know the lifetime specs touted by Formlabs listed here say that the tank needs to be replaced after either a set time, or a set volume of resin or number of layers have been printed - whichever comes first.

I had been pouring Tough 2000 , Elastic and Rigid resin out of the tanks after each use in hopes that would extend the lifetimes. I recently noticed a little spot under my Tough 2000 tank which had just marginally passed the “weeks exposed to resin” requirement. Support has told me to switch the tank (they have graciously given me a coupon code for a new tank free of charge).

Now, I have a couple of questions that I hope can be answered…I don’t think there has been much transparency on this topic:

  1. Has Formlabs been doing continued long term testing with tanks, and is there any further information on tank lifetime that can be shed? I presume what’s listed is a conservative number and it would be nice to know a) whether internal testing has shown this can be extended, or b) whether there is work being done to extend the lifetimes. I am admittedly running some tanks past their lifetime with no issues, but just carefully inspecting the film before each print.

  2. Does pouring resin out after use extend the lifetimes at all? Is this something Formlabs has even tested?

Hoping this thread may shed some more information on tank lifetime. I’m OK with the cost of replacing tanks as a consumable - that’s the cost of business, but I admit that I’m still dissapointed that the LT tanks on the Form 2 lasted longer.


This an excellent question, I too try to preserve the life of the tanks and am scared that at some point I’m going to have a leak and ultimately a disaster, look forward to some more precise recommendations on tank life and preserving that life


I, too, would really love to get more information on those points. Caring for the Form 3 tanks is more onerous than the Form 2 ones, and I find it particularly constraining given that my usage patterns tend to be intermittent. Any tips to prolong tank life when they’re not in use would be very welcome.

Also curious if the v2 tanks have better longevity than the v1 ones.


In my opinion this may even shorten the lifetime of the tank as it involves some manipulations with the tank which itself can damage the tank.

There are three major processes going on, which shorten the tank lifetime:

  1. Aging of the plastic - the plastic film just ages (oxidation, UV light, etc.) and makes it more brittle (co-polymerisation of organic molecules and chemical reactions). If we take in account that the shelf life of new, unopened tank is one year and after we put it into the printer Formlabs counts 6 months we can consider the “guaranteed” lifetime of tank (in case we have low usage) to be at least one and half year from the moment of production.
  2. Fatigue of the material - each time we print a new layer and the laser moved under the tank the film bends and in long term results in material fatigue (film breaks despite we don’t apply big forces). There is build in limit of ~5 liters resin before tank will show message for replacement. If the printer was not used intensively we can’t reach this limit and dominant factor becomes (1). I guess Formlab considered the worst case scenario (printing 25um layers) so using lower resolution printing can extend the lifetime of the tank (we can print more liters of resin safely)
  3. Mechanical wear out - despite that laser unit has smooth top surface, it still has some abrasive effect on the film which can be substantially increased if there is dust in the room where printer resides. Keeping the printer away from the dust can prolong the tank life

My point is - if the printer is away from dust and we don’t print intensively we could safely (but on our own risk) use the tank for an year.


I can’t see how the tank could ‘know’ that the resin had been emptied from the tank. I suspect the control is a day counter starting at the time the tank is first registered with the printer.


There is an miniature EEPROM embedded inside the tank (tank ID IC) which holds information for the date when inserted for first time. After that the printer counts how many days passed since this first usage, alert will rise after half year of usage or after some number of printed layers was exceeded.

The tank doesn’t know is it emptied or not


This is perhaps an educated assumption - but I’d like to know or see some actual emperical evidence from Formlabs if possible. It’s been a while since they’ve released the V1 and V2 tanks and I would expect that they are (and if aren’t, should be) doing some extending life time tests.


Whether the software “knows” the tank has been emptied is beyond the point here - that’s just a dumb software counter.

The tanks are given a lifetime because the resin eats away at the bond between the films. My main question is whether emptying resin will slow down that process and thus increase REAL world lifetime of the tank, not the software counter lifetime.

Form 2 sitting with resin for 2 years

I recently attended the Formlabs webinar on Factory Solutions. This is a platform developed by FL to assist and advise companies setting up production environments with Form3 printers. So that way you may have 10 or 20 units (and tanks) printing.

I asked specifically how they’d advise to manage tank decay in that scenario, since you can imagine someone planning to deploy such a system, might be a bit more serious in getting the best return on their inverstment. The answer was the usual “It’s just a consumable”.

I can imagine, it has been a huge effort to get the Form3L released during Corona. But I sincerely hope there is some work being done improve things here, either through a recycling program or by rethinking the tank assembly or SKU to have less waste (and cost), or some other out of the box innovative thinking.

It might be a consumable but I guess we should be getting advise from FL to safely extend the lifetime of the tanks, not just a counter to know when to buy another one.
Not only environmentally, but also as a way to increase the value proposition of the printers.


Hey All!

Just wanted to let everyone know this thread is on my radar, and I’m getting some answers from elsewhere in the company for you!

Should have a longer response ready in the next day or so.


Thanks @DKirch! :grinning:


I was recently in touch with the European support department about this. They did suggest emptying resin out to extend lifetime of a tank, but could not guarantee it. So this kind of raises the question of what happens if we follow the advice, and the tank leaks on week 11 (when using Engineering resins or Tough, for example).

As a hobbyist who does not run a business or company, having to replace a tank after only maybe having time/funds to print 1 cartridge becomes very expensive in the long run, and may turn out to not be a viable option.

What to do with left over resin in resin tank?

Hey everyone!

Haven’t forgotten about this! Just some unfortunate vacation timings from some folks here :smile:

Still on it, and apologies for the delay!


I had started a thread back in mid-July: Costs of maintaining a large resin library
It had to do with this, so I guess it lives on here…

As I try to grasp the economics of this for my case (independent designer, working alone), what I am seeing is, you might best settle on only 1 type of resin to do it all (such a pity!).

If you print about 35 prints with a 250-day tank, (or 1 print a week) you might add about 4,5 bucks of tank cost to each print, which is probably still less than the cost of the resin in an average print.
But if you divide that usage in 2 resins (ex: Draft and a second one for final parts) you are already paying more in tanks than in resin (or your prints need to be more than 50ml in average), which makes less sense.
If you want to have an “aggressive” resin too, for special cases (let’s say Elastic), and you use it less, obviously, it gets awkward: Given I have a project that needs rubber-like parts, I’d have a cost of 30 bucks per print on tank alone, if for example I need to print 5 times to fully develop a part.

I can translate the costs, but it’s a much harder sell!
We need a way to stop decay in-between prints…

Some might say the printer is not for me… But for who then? Only high-volume users? Isn’t this advertised as a prototyping machine too?

Or am I missing the point and this is the wrong approach to account for the cost of tanks?

PS: values are approximate to make for easier numbers (.ie tanks: 150usd)


So I just realized Dashboard has a lot of improved statistics - including nicely organizing tanks and showing lifetimes, etc.

I’ll go out there and admit that I’m running some tanks past their suggested lifetime. For example:

  • Black @ 107% - 30000/75000 layers, 269/250 days
  • Clear @ 114% - 10000/75000 layers, 286/250 days
  • Durable @ 103% - 11000/75000 layers, 258/250 days
  • Elastic @ 272% - 2156/25000 layers, 204/75 days
  • Flexible V2 @ 113% - 7405/75000 layers, 285/250 days
  • Tough 1500 @ 104% - 9700/75000 layers, 262/250 days
  • Tough 2000 @ 180% - 3945/25000 layers, 135/75 days

I check the undersides of the tanks before every print, as well as inspecting the inside of the tank by gently scraping the bottom with the provided plastic tool just to check the film. I don’t notice any signs of wear across all the tanks. This is probably because I actually am nowhere near the max # of layers printed per tank.

I’m somewhat taking a risk here to see how far we can stretch the tanks. It’s not clear whether the engineering team has actually tested “days with resin” independently from “layers printed”. For example, will a tank which has resin stored in it for >250 days and zero layers printed, fail on its first print? Or will it simply cause the “layers printed” lifetime to be less because of a prolonged chemical reaction between the resin and the bonding between the gasket & film?

Also, knowing what the failure mode is can be helpful because if it’s slow and visually detectable, then users can continue to use their expired tanks as long as they keep a very close eye on the tanks. This not only will extend consumable life for those of us who stock a lot of resin types, but don’t print all the time, but will also be somewhat of a “crowd sourcing” of information for Formlabs in case they don’t have the time or resources to do better lifetime testing on the tanks (something that I would like to see regardless).

How Long Can you Store Used Trays?

I can chime in with one more:

  • Clear @ 117% - 12848 / 75000 layers, 293 / 250 days

I always assumed the issue is primarily around degradation of some adhesive used in bonding the films, but haven’t seen anything specific to support that speculation. It’s easy enough to inspect for damage, but my concern is a seam failure when the film is placed under tension.

Unless Formlabs completely locks out end-of-life tanks (which would be a showstopper for me personally - I’d sell my Form 3 and cancel my 3L order), some users are always going to push the boundaries. Learning more about failure modes and the specific testing that informed their guidelines would be really helpful in appreciating the risk and knowing what to watch for. I’m also hoping a v3 tank is eventually released which solves the problem for good and adds a magnitude of order to shelf life (even with resin in the tank).


@DKirch Any word yet on @leonhart88’s original inquiry?


Hi all,

This topic needs reviving.

My tank with Elastic expired today.
Inspecting it I discovered something strange, but I cannot say that this comes from the resin exposure or it was already like that.

The other side looks fine:

I realised looking at the usage statistics of @leonhart88 that he has his at 272% (!!) :hushed:
Would you dare keep on using this?
Would you say this is because of resin exposure? I can’t recall how the tank looked like when new

I printed a couple of things the last couple of days. No problem…

Has someone actually had a catastrophic failure with an expired tank?


I’ve seen those squiggly lines before too…it might just be weld lines or something from injection molding. I don’t think that is the main area of concern regarding tank lifetime…it’s mostly the interface between the two films - ie. the black gasketed area. This is the area which bonds the two films together and the resin supposedly attacks the glue or weld at the interface.

My tanks are still working fine. I recently changed my Black and Elastic tanks, but there weren’t really any significant signs of wear other than scratches from the LPU rollers and some dust that eventually gets between the films…so I probably could have kept using them. Many of my other tanks are still over 100% and I’m using them constantly.

What’s important is that:

  • I inspect the tanks before each print

  • I pour out the aggressive resins (FL has told me this won’t make a difference but they have not given me any data to prove this and intuitively I would think that reducing the weight and stress on the interface layer would help)

  • I am still significantly under the liters of resin printed lifetime

Note that I’m not endorsing others to use the tanks past their lifetimes and I am not liable for any spills that may occur. I’m just not convinced that there has been extensive lifetime or HALT testing on the tanks - especially in situations like mine where I stock many different resin types, but don’t necessarily print a large volume per resin type. Lifetime characterization under different scenarios can be difficult and time consuming to do. The lifetimes are probably conservative values and likely more accurate for those who print much more often than I do. I also like pushing things to the limit :slightly_smiling_face:


I would be interested to hear what the failure mode was for over-used tanks. Or if that is not possible, maybe the criteria people are using to decide that the tank has come to the end of its useful life.

I’ve just realised that the dashboard and printer show different life expectancies.

For my present tank:
Dashboard 39% – Layers: 29925 / 75000 Days: 44 / 250
Printer 58% – Hours printing: 347 / 600 Days: 45 / 250

How far past "expired" will a resin tank still work?
How far past "expired" will a resin tank still work?