I’m not quite getting the full year of shelf life out of my resin. I use my printer sporadically (typically a LOT when I’m in the middle of a project, then months go by while it patiently waits for another print).
I store my resin in a dark place at room temperature. I live on the west coast (near Vancouver) so the humidity is a touch on the high side.
I’m looking for any advice you might have on preserving my resin to extend the shelf life. I was thinking of trying to store a few bottles in the fridge to see if that helps. Any thoughts? Any idea what the perfect temperature would be to maximize effective lifetime?
If it works, I’d be game to buy a dedicated mini-fridge - sadly, I’ve already had to throw away hundreds of dollars of resin due to it going bad (i.e. not producing successful prints).
If anyone from Formlabs reads this, I’d be happy to send back some bottles that have not reached their expiration date but are producing failed prints, if you care to investigate.
If anyone near Vancouver reads this and wants to “time-share” resin inventory with me, reach out!
99% of chemical reactions go slower if they are cold, and as a guide, for artificial age testing of polymers, the rule of thumb is 10degrees C = doubling of the time (you can look up the exact formulas if you want). This is used all the time in product lifespan validation. This means that if you drop it 10degreesC, you should double its life.
There is of course a limit. There will be a point where you start to separate the individual components of the resin due to their different behaviours at low temperatures, i.e. any light solvents/oils in the mix will come to the top, and heavy particles such as the UV absorbing additives will fall to the bottom. Basically, don’t go too cold, and do shake/stir it thoroughly before use. If you do go too cold, they might never re-mix successfully.
Having said all that, I keep my resins at room temperature, and some of the more rarely used ones are well over a year old and I haven’t had any issues with them.
Great question about the ideal way to store resin. Section 7 of any of our Safety Data Sheets will be the best reference for storing resins. For storage temperature, we advise between 10 and 35°C.
Since we also advise always shaking or mixing resin before use - especially important after being in storage - it might be helpful and perhaps optimize the lifetime to shake the resin bottles (maybe once or twice a month) if you’re storing them for many months.
For anyone curious about more general tips to maintain resin, we also have a Resin Care article with an overview.
I’ve considered making a ready use resin cabinet with a PID heater control to maintain the temperature at 80F and bottle rollers to automatically roll the bottles at 1 -5 RPM while in storage. Thoughts?
If cold temps typically increase shelf life, then keeping the bottles heated might reduce it.
A 12" long 1/4" steel rod with 1/2" length of one end threaded, you can then double-nut a fender washer (small enough to fit into the bottle opening) cut on a bandsaw into fan blades, twisted to have slight pitch. This can be put down into the bottle as a mixer. You’d want to smooth the edges, obviously, so you don’t hack into the bottle. Kinda like a mini-version of a drywall mud mixer
For general use, I don’t think refrigerating material is a good idea. Each time you pull the material out of the refrigerator it will need to warm up to room temp before use. Continued temperature cycling is probably not very good for the material.
That said, if you know you’re going to go months between prints it’s probably a good idea to refrigerate and agitate the resin regularly.
I’ve gone for months without printing and the Formlabs resins seem to be fine just out in the open. I don’t even empty the build trays. Just mixing and printing without issues. No issues for the Vorex resin either but I prefer the actual Formlabs resins.
I do sometimes go months between resin uses, so perhaps there’s an opportunity here. I don’t think my normal fridge will do, since the ideal fridge temperature is < 4°C which is a little colder than the storage temperature Stephen mentioned from the datasheets (10 - 35 °C). When I get more space I’ll revisit the idea of getting a dedicated refrigeration unit kept around 15°C and building in some kind of autonomous mixing feature, and report back if it impacts my shelf life.
