Experimenting with Expired Resin

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).

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Addendum: After some further experimenting… I think the simplicity of the shapes I was printing went a long way toward the degree of success. Basically they were just vertical walls extending away from the build platform.

A repeat of the more complex Feb 2015 print still came out flawed, even on the higher Clear V2 power setting, due to failure during the support structures:

However the tray was also getting low on resin toward the end of the print, which may have contributed (it wasn’t quite perfectly level and I think the resin pool may have been a bit thin in that area).

Regardless, it was still way better than at the lower White V1 setting:

A lot more methodical testing would be needed to draw firm conclusions, but the above indications may make it worthwhile for Formlabs to investigate letting us nudge up the laser power when working with older resin.

Again, without endorsing the use of expired resin, I’d love to hear from others who’ve pushed the envelope here.

I just wanted to share my positive experience with printing with flexible v2 resin that is 7 months past expiry date. First thing I want to mention is that I had bought the resin for a client project that never ended up materializing and so it was still in the sealed bag.

With that being said when I removed it from the bag and shook it a bit it was like molasses which didn’t seem promising at first. What I did to liquefy it was to use a hair dryer and heat up the cartridge for a few minutes shaking every so often to feel viscosity. once I had it feeling close to what it should feel like I shook the hell out of it by hand for almost 30 minutes straight making sure to shake it in every orientation. From there I popped it into the form2 and proceeded to print 3 thin gaskets that came out really nicely. I am currently printing a second batch of the same gaskets now and will post pictures once it is done. It seems as far as flexible resin is concerned as long as its in a sealed bag and kept in a cool dry place you can get away with using it well past expiry date. Just make sure to heat and shake it like crazy which worked for me.

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