I use a little alcohol on the pdms layer and carefully clean that with a microfiber cloth first. I wipe the sides with a clean microfiber cloth and moisten it slightly with alcohol if needed. Alcohol will attack acrylic with prolonged exposure. A quick damp wipe shouldn’t hurt. Damp being just a tiny bit.
They are right, never contaminate your new resin bottle. However resin from the tray was already poured into the bottles so I now have to filter the whole lot 
Also - this machine is rather high maintenance in terms of costs. If I start having significant issues I just change to a new tank. I see cleaning the inside bottom of the tank as trying to delay the inevitable of replacing the tank. Just do it! I usually have a bottle of goop order coming about once a month. Add a tank to it and be done.
I am not in this to go on the cheap. I just want my parts to turn out as best as possible with at little failures and annoyances as possible.
Bill
My tank was on its way out so for kicks I put it in my ultrasonic cleaner and was able to substantially clear the pdms. For kicks I tried rain x on the cleaned pdms but I applied it with the metal scraper rather than any cloth or paper towel. It left the tank hazy but that cleared up with my finger tips and some yellow magic. Tank works beautifully now. I’ll still have to replace it since the plastic frame is really falling apart.
At least I know yellow magic doesn’t hurt the pdms or the housing. Something to keep in mind in a pinch. Rain x can be risky to use on the pdms because it is so fragile. I think the haze people see is the pdms getting pitted from the peel.
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I was thinking I still have never seen a better print than what I get with clear resin. Pigmented resins settle on the silicone and create the fog haze. I have to scrape this with my metal scraper. Even though I rounded off the corners I still dont know if I am damaging the silicone. So pigment resin prints are still lesser quality than clear. With clear I never have to touch the silicone.
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Thanks, I was wondering about the pigments.
I have been able to remove the majority of the haze I was getting but noticed over time the PDMS doesn’t clear 100%. I am thinking the surface eventually gets chipped or torn, maybe that is accelerated from pigments and peel process or maybe it’s just wear and tear.
My big question was do the pigments just add color or do they have a functional purpose and increase details. Guess they just make the parts pretty.
Next resin is going to be the clear.
They just add color. Over time they separate which is normal. Just got mix it up real good for a few minutes or until the PMDS is clear before you print!
You made an interesting statement: “We have printed on some very foggy PDMS layers here at HQ with results that are not distinguishable from a fresh PDMS layer.” Could you post a photograph of what “very foggy” looks like?
What effect have you seen by using IPA for cleaning the tank? I do not do it as a practice, but recently some Ver3 Black completely adhered print to the tank bottom. It was the second tank this happened to and I damaged the PDMS layer scraping it off. The next tank, I drained/ emptied and then let Isopropanol- isopropyl alcohol 100% sit for about 10 minutes and then scraped out the material with a Delrin scrapper. It appears fine and I know from our coatings of HMDS and PDMS that our KMG Isopropanol does not affect the material. Any information on what I might see if I install this tank would be greatly appreciated.
IPA is fine for cleaning the silicone layer on the bottom, but the tray itself is made from acrylic which breaks down in IPA and will start to crack.
Thanks Zachary, but it should be noted that as plastics engineer with 30 years experience using Acrylic and Polycarbonate, Acrylic is a generic name for Polymethyl methacrylate and although there are various formulations they typically start to show cracking or crazing after long term exposure and wiping with isopropanol/ IPA would not have severe effects unless it is immersed, heated and or exposed for long periods of time. Additionally, products such as Acrylite UV like the amber coating to filter UV light inherently give it more chemical resistance from the UV coating. So I would say that care should be taken but users should know that wiping and then drying the surface would not cause immediate concern.
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Formlabs has highly recommended against using IPA on any of the acrylic parts
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In my case I have a version number issue. I have a tank with white in it and it was V2 and when I ordered another batch of resin its of course V4. The V2 came from a distributor and I was not savvy enough at the time to make sure I was checking everything. So now I’m told we can’t even mix versions. Given this tank only has 1 liter through it I want to clean it and change it to a V4 tank. Sounds like its a simple drain, wipe it clean, and start over?
Yup. Your printer will warn you upon starting the print that the tank is registered with V2 resin, you’ll be able to override this warning and the tank will change to V4.
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I have re-coated my tanks at least twice now, and there’s no substitute for a clean fog free PDMS surface. However, printing on a foggy PDMS doesn’t mean outright failure. Depending on how bad it is, you might get surface quality problems as the laser beam becomes “diffused” rather than sharp.
Regarding the cleaning of the the tak, I have had to clean the tanks on quite a few occasions, and found that Dawn blue dishwashing liquid does a great job of breaking up the resin and cleaning the PDMS. It can’t remove all the caked in and dried out resin on the sides of the the tanks, but it will certainly remove any of the liquid resin.
One of the nice things about it is that you can pour int into the tank, then using nitrile gloves, or bare hands you can rub the PDMS surface to remove any resin of it (just make sure you don’t scratch the surface with your nails). It works well because it lubricates the surface, and prevents your fingers from sticking to it when you rub the surface.
I’ve use IPA only once, and it did a number on my tanks and the PDMA, so never again.
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I still use YM here for the tank cleaning with no issues. You do need gloves for it because it is more potent than dish liquid.
As far as tank clouding you can still use the clouded areas but I find it is best to use the dying areas for courser printing such as 100 micron. For 25-50 it is best to use the clearest areas or change a tank.
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I still would love some people to make a video on How to properly clean after a print failure as well as resin changes and actually how to inspect these things visually without dumping the resin on the floor it seems Formlabs doesn’t wanna deal with anything remotely dealing with cleaning…since they want you to just buy a new tank …as it were