That's an incredible amount of salt that gets used. No wonder the underbodies rust.
Given the cost of the new exhaust systems on the new cars these days you'd be nuts not to undercoat it!
Interesting, never heard of the beet juice brine one before.
Don't see many undercoating places anymore.
Salt isn't feeding as much until temps break the freezing mark. That suggests washing it off when above freezing.
"Rustproofing" didn't ensure door drain holes ect. were in working condition after the tarry substance was sprayed in panels.
Trapping moisture did happen in areas.
Holes and plugs were used too.
Salt in a frame hole doesn't care if the outside of the frame is tarred.
But there were cars undercoated the owners of which didn't worry about washing salt off when temps broke freezing because they were "rust proofed".
Which of course resulted in severe rusting.
We have an area of the midwest called the rust belt for multiple reasons.
One of which is salt being dumped on the roads.
Salt too when temps are low enough ; help ice harden. Home made ice cream making employs salt. (Not for flavoring.)
So when temps are cold sand gets mixed with salt. Evidenced inside wheel wells where rustproofing can get stripped in a season if enough sand is driven on.
Better to sand and salt then pack snow into ice and create inches of ice.
We been doing that on my main road as the county seems apprehensive about scraping the repaired areas resurfaced last summer. Slot car two tracks worn into the ice.
Kinda like my dirt road I maintain. L.o.l.. But on our road you can see the salt being tracked onto it at it's end at the main road. Farther with time as winter season progresses.
A co-worker and I used to build pipes for wash systems on one worksite. 2 inch by several feet long with nozzles of types and location of our choosing.
Co-worker was considering making a set of pipes to drive over in winter to wash the underside of vehicles.
Some car washes have a single at the entrance.
One of which I use and drive slow over in the newer truck.
The 2008 plow truck you step carefully on the tree-bar on the driver side to get in ; and note the flex.
Don't look at the rest. And especially underneath.