Resin shelf-life? Old resin?

Hello all,

I finally started using my Moai again after a really long time. Still happy with the purchase but I have some bottles of hi-temp grey and clear that I purchased about 14 months ago. I did a half-assed job of shaking up some grey and put it in an old PDMS vat that I had left resin in for at least 6-9 months that I cleaned up with some 99% ethanol.

Perhaps a bit surprisingly, I’m getting decent prints, been playing with the latest Asura and updated the firmware. I’ve been doing some simple test prints to get back into the workflow and the only thing I’ve noticed is that resin seems a bit undercured, and it seems more translucent than it should be.

It’s pretty cold where the printer is located, thought it’s probably above 20C but not much. I’m looking into ordering the heater add-on since I have the original Moai.

So my questions are:

  1. What are the changes in performance for older resins? Cure faster? cure slower?
  2. I see the names of the resins have changed a bit. Is hi-temp grey the same as Nex Resin Grey?
  3. Has my grey gone off or is it just translucent because I did a poor (deliberately) bad job of shaking up the bottle that’s been sitting on the shelf for 12 months.
  4. Any suggestions for getting best prints from older resin? Unfortunately I’ve got about 8KG of resin here I want to work through before buying more and/or upgrading to the Phenom.

Thanks in advance!

1 - you might get surface artifacts like salmon skin or ragging, you may need to increase laser power, but see point 3
2 - same same
3 - you really need to shake the shit out of the bottle before using for at least 1 min.
4 - it should be fine tbh, just shake it properly or store the unopened sealed bottles upside down.
5 - untill your heater arrives, just use a hair dryer to warm the resin before printing, either in the bottle or in the vat. stirring the stuff in the vat before each print is best.

Alright. Thanks for the feedback.

Any idea the maximum shelf-life of the resin if stored at a reasonable room temperature in the unopened original bottles?

After a few more tests I’m going to switch to a spare brand new PDMS vat I have with a well-shaken bottle of warm resin but I’m not having many flaws appear at 51 power with the 1.18 firmware.

(Perhaps I’ll take some pictures of the slight issue I’m having with a circular hole feature, maybe I’m having a brain fart but its as though there is partially cured resin dripping but it’s in the opposite direction of gravity. I’m starting to think it’s resin running off build plate and into the model since the model is resting directly on the build plate and the hole runs at about a 45 degree angle starting almost at the build plate.)

Cheers

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the resin should last for 1 year before it starts to go bad
you can try stirring up the resin well before use and change the settings a bit, maybe higher laser power, it would overcure the model a bit but it should give a more consistent success rate

Alright. I purchased some of this resin in Sept 2018 so I assume I still have a limited time to use it. Can the “going bad” be slowed by adding inhibitor or something else? How exactly does it go bad? It’s in the original opaque black bottles so I assume it’s natural degradation of inhibitors?

I haven’t yet had anything I would consider failures with this “old” resin, even though I didn’t really shake it very well before I started using it. After a few days some of the earlier prints have turned to the color I would have expected so I assume it’s due to a lack of curing under the small UV light or actual print process but all the features are as good as I would expect in this detailed model.

I haven’t found any failures that I can’t explain away with the old vat, low temperature and lack of mixing yet.

Any resin, after a long time, will starts to decay. It makes the chemicals loses its properties
I’m not a chemist to explain you all the details, but i know that it would results in improper curing, layer separation and it just makes your print either hard to success, or printed badly