Free: Contests & Raffles.
Uh.... gotta throw the proverbial BS out there....take no offense... How does this work better than forzen water? If the addition of salt to water lowers the freezing point of salt water versus plain ol' water, this would not affect the actual temperature of your frozen jug. A frozen jug of water next to a frozen jug of salt water are the same temperature, but have differing melting/freezing/boiling points is all. I would argue that there is no discernable difference.
you don't need a cooler to do the test, you'll see the results faster if you freeze one water bottle and one brine bottle for the same amount of time in the same freezer. Then just set them on the counter and see which one melts first...
So the question I had, does the salt make the expansion less significant or slower, so that the milk jug doesn't crack.
To keep your ice jugs from bursting while freezing, fill and freeze them in increments, say in thirds. Been doing this for many years and they don't seem to rupture this way. ( No geology degree needed... )"Latent heat of crystalization..." Baaah' your big words don't scare me!