Well unless you mixed it in an aluminum container, he has his chemical references crossed (
link).
Just to give you more
fuel shared experience for the discussion with your
know-it-all misinformed partner, feel free to share this:
I have been making master-batch lye solution somewhere around 4 years now, and others here for longer than that. If any of us had had our stored lye solutions explode, you can bet we would have warned others about it and would not be touting it as a useful, time-saving and acceptable practice!
I keep my master batch lye solution (50% water to 50% NaOH as is quite common for master-batch lye) in a tightly-lidded PP (#5) container (once it has cooled, of course) for extended periods of time. When I first make the solution, I allow it to cool in the mixing vessel (also PP #5), with the lid in place. It is not an air-tight lid, but I definitely keep the lid on to prevent the escape of evaporate into the room; any evaporate falls back into the container from the inside surface of the lid. Once the outer side walls of the container are cool to the touch, I fill the lye storage bottle(s) with a bit of clearance from the top, and tightly screw the safety lids to ensure they will not leak if knocked over. The lid is one of those child-proof lids that you have to push down on while turning it in order to remove it. They are absolutely leak proof because I have tested them to make sure. They are then stored inside another larger HDPE container standing upright to ensure that if one of them ever develops a leak (and they never have as yet) it will be contained. Not once has any of them ever spontaneously erupted, nor have they ever even expanded. They are clearly labeled, weights recorded and all that good stuff.
Over time as I use portions of the 50% solution, the bottle becomes less full with solution and has more air with which to interact, and the solution can become slightly more viscous, which can also be influenced by lower temperatures. As the level of liquid diminishes with use, and seems to be thicker, I shake the bottle prior to opening to ensure it is well mixed. This has never caused any eruptions, explosions or even bottle expansions or tops popping off.
Maybe the partner would like to take a look at this table or the article from which it comes:
The above table is from this
site, which discusses safe storage of liquid sodium hydroxide. You can read more about how viscosity factors into the equation when storing lye solution long term in the sited article.
And just to let you know how non-explosive it is, I have transported master-batch lye in my car while driving from my home to elsewhere (for off-site soap making.) There has never been an issue with exploding lye solution in my car. If there had been, you can bet I would either not be here to talk about it, or I would have warned y'all about it.
They are not bottles of nitroglycerin, for heaven's sake and this is not some Hollywood Western where I'm riding around over a rocky road in a buckboard wagon with a wooden boxful of nitro bouncing around in the back.
Edited to correct error of type of plastic I use for storage.
