Dunno about OP, but the advent of Long COVID comes with a 5x increase in new diagnoses of POTS. Lotta new passengers on the electrolyte train. On high symptom days, I have a junkie-like relationship with calcium antacids and salt shakers.
Yeah, last time I bought one the powder captured enough moisture that the can corroded. I only drink it about once a week so there's powder sitting for a while
This is probably unnecessary. The powder itself should be very shelf stable so I would have just repackaged it in vacuumed sealed bags or get an attachment to vacuum seal the jars (vs heat canning).
Just got that vacuum sealer mason jar attachment and use it every day for coffee. Love it!
If for nothing else over OP's method of choice, with the sealer, you can take what you want and reseal without heating up a whole oven every time.
Credit to OP for using what tools they had available, but if this method improves your situation, they'll be spending more time hearing and sealing it than drinking it, plus repeated heat cycles may possibly degrade the product.
I have a core memory of chipping away at the brick of what had previously been powdered Gatorade that had since formed into a single solid mass after sitting in the pantry for several months.
It's called dry oven canning. The oven heats up the contents of the mason jar, so when I put the lids on and let them cool, the air inside comes to a lower pressure and we get a vacuum seal. Same notion as you see with jars of salsa, where the little circle on the lid pops up only once you crack the seal