How long will the resin be usable if I just leave it in the tray after a build?


How long will the resin be usable if I just leave it in the tray after a build?

That is if I'm too lazy to empty the tray and just leave it sitting there exposed to the air. Would I be able to just pour some more in, say after a day, week or month, and start a new build?



We haven't strictly quantified this, but yes, you can do this for many weeks, as long as the resin isn't exposed to the blue light (405 nm wavelength) that polymerizes it. You can protect the resin from exposure by keeping Ember's large amber window closed.

There's a related issue that you'll want to know about, when using the Standard Prototyping Resin (PR48): If it's left in the tray, over time, the UV blocker diffuses into the PDMS (resin tray window), decreasing its performance. Therefore, it's best practice to drain the resin from the tray, as this extends its operable life.

I'm happy to answer any follow-up questions, if you have any.


What is the time frame of the diffusion? Hours? Days? Weeks?


I've learned that best practice is to clean out your tray if it's going to sit for a whole day without use. It doesn't take long to do if you get a good tray cleaning setup going...

That said, I'm not so sure anymore about using IPA to clean the tray. I used to use this to clean mine, but I'm very unhappy with how quickly it ate away at the adhesive, ruining one of my PDSM windows (the Form Labs forum discusses this and some users stay away from IPA in the tray). My other tray/PDSM was ruined by my Ember crashing/freezing mid exposure! Cured everything in sight after a few hours...

So far, the tray and PDSM design have been my only disappointment with the Ember, but based on the Form Labs forum, there's similar issues and checking out that forum would be a good place to find some tips/tricks.


My experience with IPA to clean the tray was a disaster. Avoid at all cost!

That said, I still don't have a good method to completely clean out the resin tray. Just tipping it on its side does a fair job of removing the bulk, but there is always a light film left behind. I can only image that that film is doing as much damage as full tray - so I have not made it a practice to clean the tray every night. This may explain some of the minor issues I have.

What do you have in place for a tray cleaning setup? I was thinking of printing a jig to hold the tray upright while it drains - and maybe leave it overnight in a closed cabinet.

Any suggestions for removing the thin layer of residue?


Scott, I have a "jig" that's really just two blocks with a catch tray underneath. (It's in a dark corner of my lab on a shelf). My goal is really just to drain out the resin from the edge/crack between the PDSM and the window...sometimes I'll wipe that light film off afterwards with disposable glass cleaning clothes I got at Home Depot. I can't remember the exact brand, but its great stuff and absolutely no lint...

I'm disappointed that IPA is recommended as the go to cleaner in the manual when its clearly bad for the adhesive in the tray design...

I think the best thing would really be a mini squeegy...that's what I'm using to clear off my PDSM prior to buffing with the same glass cleaning cloth with a tiny tiny amount of acetone...if the IPA eats away at the adhesive, I'd hate to find out what acetone falling in the gap would do!

I don't know that denatured alcohol would be any better?

I'm going to have to order two new resin trays after learning my hard lesson with IPA and my printer crashing mid exposure and ruining my other tray (bad week for my ember).

One things for sure, I'm definitely going to try applying Rain X to one of them to see if this helps at all...


Thanks for the feedback.

The IPA works great for cleaning the prints, it just seems to have such a poor reaction with the tray. Let us all know how the rain-X works if you get to try it.


Will do! But give me a few weeks before I'm back up and running and can post some results. Cheers.


Thanks for sharing your experience about this. I'm working on providing better guidance about how to clean the resin trays in a way that doesn't damage the adhesive.

Leaving the resin tray in a tilted position, to allow it to fully drain, and using a squeegee to clean the PDMS are both very good ideas. Once we've come up with a better workflow to clean the trays, I'll post them in the user manual. Meanwhile, I've added a warning to the user manual about the use of IPA on the resin trays.


An update on my tray experiences:

A squeegee is a must for cleaning the PDMS! I just cut a piece off our the squeegee we use at home to clean'll want to snip two pieces off; one from each side of the squeegee so your significant other doesn't notice there's 2" missing from just one side ;)

I noticed there's trenches on the two longer edges of the PDMS, so it's best to squeegee along the shorter edge of the PDMS.

I like to put a few drops of acetone on the squeegee and then dragging it across. So far, acetone hasn't had the same peeling effect as Isopropyl on the PDSM adhesive. However, if you drag too much across the PDMS and it pools around the acrylic tray, you'll get some serious tray hazing. I haven't found this to be too detrimental to the print though!

I've also had great luck with Rain X! I treated one new tray with it by dumping about 25ml in the whole tray and creating a vibration effect with my hand. I then dumped the same Rain X into a heavily used tray. The Rain X did a great job of cleaning up the cloudy PDMS window in this tray! I repeatedly used a squeegee on the PDMS window while the layer of Rain X was sitting in the tray. Again, no issues so far with the Rain X eating away at the PDMS adhesive.

So, the following are definitely "must have tools" for caring for your trays:

- Acetone

- Squeegee

- Rain X

Overall, I've had very bad luck with any cloths on the PDMS. Even the most lint free / smoothest clothes seem to either stick or introduce some fibers which really get embedded on the PDMS. I find the squeegee really is best, followed by fogging with your breath...and repeating as required.

I'm still experimenting though, so any tips are appreciated!


Great share about your process. Thanks for posting! We use squeegees in our lab to clean trays, and they work great.

And it's good to hear about your experience with RainX. As I understand it, RainX is effectively liquid PDMS.


Thanks, all, for sharing your tips here.

Just a quick word to the wise: I would advise caution when heading out to buy "Rain-X." Depending upon which product one buys under this brand, the contents of the bottle vary greatly.

Rain-X Original Glass Treatment is composed of ethanol, acetone, isopropanol, and sulfuric acid, in proprietary amounts.

Rain-X Plastic Water Repellent is composed of water and propylene glycol, again in secret proportions.

@s.arthurkiss - can you specify which Rain-X product is working for you?



Oh! Good to know! I'll confirm tomorrow, my bottle is in my lab.


Sorry for the delay. The product is:

Rain-X Original Glass Water Repellent

It works great! I did a test where I let the resin sit in my tray for 2 weeks without printing. Every few days I would run the squeegee over the PDSM to wipe off any stuck on resin from ambient lights. I noticed right away that it just wipped off so much easier. After two weeks, I poured all the resin out and used the Rain X as my main resin tray and PDSM cleaning product. I sloshed a thin layer all around the tray and even wipped with my squeegee. It worked great! I then finished off my cleaning my PDSM with a bit of acetone, fogging, then wiping, then repeating. PDSM was clean as ever!


Great Tip!
Giving that a try tomorrow