Tough resin dispensing problem: separation in cartridge

This morning I put a cartridge of tough resin in my Form2 for the first time in a few months, and my print stalled trying to fill the tray before printing. I pulled the cartridge out and tried the bite valve by hand and sure enough, nothing. Cap was open, but no resin flowed. I had already shaken the cartridge for minutes, so as a last resort I poured the cartridge out into a cup. What came out was both liquid resin and huge clumps of goopy resin.

This tough cartridge is the same age as other durable resin I have (in fact I checked another tough cartridge of the same age, same problem). So this may be unique to tough. The cartridges are stored in a dark cool place. One of them was sealed (new).

Now it may be that these are beyond the recommended shelf life (they’re V3), but if you have any tough V3+ and having trouble dispensing, this may be something to check.

I was able to stir the resin back into liquid form and refill the cartridge. (The print is going now, and may fail…)

The resin definitely needs to be mixed very well if you haven’t used it for a while, but it also sounds like the resin could be expired