I have some Form 2 LT vats, in which eventually the resin seeps under the FEP (I’m assuming it’s FEP) surface, rendering part of the vat unusable.
Has anyone else solved this problem? I’m considering pre-sealing the inside edges of the FEP sheet to the side of a brand-new tank with something like clear RTV silicone sealant. Not sure if that would even work.
FWIW the resin in question is Applylabwork Laser Modeling Gray. Similar consistency to FL Gray V4.
See photo.
Happened to me with formlabs resin as well. Sometimes it’s just bad luck for some reason.
Sealing with silicone can definitely help.
Out of interest - Which of the Formlabs resins showed the creep under the film like in the photograph? We have had issues with draft resin, both in a standard and LT vat
Rigid resin. The tank was heavily used and then not used for a while so I guess it already started to slightly wrinkle(standard failure mode of LT tanks) and this allowed resin to dissolve the glue.
Similar here - the draft resin seems the most aggressive at the wrinkling effect, which I guess is caused by absorption of the PDMS / FEP (like) material after a period of time and it swelling
UPDATE: I took one of my vats that had a small patch of seepage, cleaned it thoroughly, and put it out in the sun all day to cure any resin that got under the FEP sheet, as well as any in the nooks and crannies. Then I ran a bead of GE waterproof silicone around the edges. That has now cured and I’m about to try a test print with the modified vat.
ALW resin works best in the Orange tray and definitely better in “closed mode”. I assume you are using open mode. Some resins stick much harder to the LT tank layer than PDMS, especially if the wiper is not used.
Haven’t had an issue with ALW Gray resin sticking to the LT FEP surface. The last photo shows the silicone seal after it came unstuck. It is not a failed print. Printing worked fine. Seal failed completely. Why do you say ALW works better in closed mode? I have thought about using one of those aftermarket cartridge spoofers but have no problem with open mode other than the silly 100ml limit.
Ahh right, I though it was some of the part you were printing. Yeah, not looking good that the silicone released!
I’ve read somewhere on the ALW site that they recommended using the orange tank.
While testing I found dimensional accuracy differences printing in closed vs open mode. Also some large thin walled parts failed in open mode while it succeeded in closed mode.
I will have to experiment with one of those aftermarket cartridge spoofers. I have found that there are far fewer opportunities for resin to go where it isn’t supposed to go when using open mode. I run a farm of four Form 2 machines (say that five times fast 
with the under-vat glass removed for ease of cleaning the optics. I never worry about resin going down that hole when running in open mode.
ALWs document for Design Concept Modeling Gray Laser material references instructions for both the PDMS and LT trays. At least in that official document they don’t recommend against the LT tray but I have been dying to try one of the Z Vat glass bottomed PDMS vats so will add that to the experiment list.
If you’re using a lot of LT tanks, why not convert one to a glass PDMS version. It’s much easier to do yourself than with the orange tanks. 
Simply push out the acrylic window, remove the fep layer, glue in glass and fill it with PDMS. Works great.
I did not know that was even possible. I will add that to the experiment list as well. Where do you get glass for this purpose?
I seal my Green tanks with this, Loctite 5145 Tempflex Paste Silicone Adhesive, no breakdown, tray still in daily use after nearly 6 months! Not cheap, but if it saves one tray, you are ahead of the game!
