I'm curious what kind of real-world shelf life folks have been getting out of their resin, and what sort of luck you've had extending the working life past the expiry date.
This is sort of a successor to @Dudemeister's thread over here. After getting mushy/failed results from grey resin 15 months past its due date, he managed to regain nearly perfect prints by bumping up the laser exposure and printing under Clear V2, which is 20 points higher on JoshK's handy laser exposure chart for different resins. Dudemeister if you're reading this, I noticed you're now shopping for nearly expired resin to play with, and I'd love to hear your latest findings.
I myself had a couple bottles of White F100W purchased in March 2014, Lot #20140211-01 . One stayed sealed in it's original lightproof bag most of the time I owned it, the other was used from time to time. They both spent most of their life sitting in a cupboard shelf.
In February 2015 (approaching 1 year from purchase date) I remember printing from the partially-used bottle on my Form 1+ and and having problems with pitting on the finished surfaces, and in some areas, layers not adhering to those below. The tank PDMS was clear, and fresher resins printed fine, leading me to suspect degraded resin as the culprit.
Today (rather, 4 weeks ago when I began writing this) for kicks I cracked the stuff open and poured it into the Form 2 in Open Mode, under settings for Clear V2 (+11 laser exposure compared to White V1). My prints directly on the base came out stunningly:
Note beforehand I shook the bejeebers out of the bottle for about 5-10 minutes, then let it settle for about 20 minutes prior to printing. Later experimenting led me to suspect thoroughly mixing the resin is a vital step.
In the past I noticed Black resin seems to last longer than white or grey. This jives with a comment from Formlabs about the pigments for that color being formulated a bit differently. Surprisingly I haven't had as good luck with Clear, but I think in that case the resin might have been much older.
I'm not endorsing use of expired Resin - I'm sure Formlabs would have a thing or two to say about that. I'm just curious to hear how far folks have managed to stretch things before having to send their precious resin to the dump.
Would also love to hear gory scientific details from anyone in the know about what actually causes the resin to loose its effectiveness (e.g. pigment clumping, slow chemical reaction, etc).