The Damp-Pro is the aluminum foil covered stuff in my previous post. (# 23) Damp-Pro is a butyl rubber adhesive covered with aluminum foil.
I't's 80 mils thick (.08") and the foil is 4 mils thick. A sq. ft. weighs .5 lbs. It's a little stiff due to the thickness. Making it a little difficult to work with.
Putting it on a surface with compound curves, like a door or floor, can be challenging. I've found if you cut it into smaller pieces
(it comes in 18" X 32" sheets) of say 2" to 4" by 12" or so, it's not to bad to work with. You will need a sharp razor knife to cut it though.
You also need a wooden wallpaper roller to force it onto the surface you want it to stick to. It's a vibration insulation product.

The white stuff in post # 24 is called "Firewall." It's like a thick paint in substance. "Firewall" is a heat and sound barrier. Living in the southern Calif desert,
I wanted something that would insulate me from the 115 degree temperatures we routinely see in the summer time around here. It's like almost any other paint,
except it's much thicker. I tried spraying on the first coat, but it got very messy and was hard to control in the small confines of the cab.
So layers 2, 3 and 4 were put on with a 3" paint brush. Better control, not nearly as messy, but much more time consuming to apply.

I know "Firewall" works. I put it on my doors and on the ceiling in Feb. & March. Last month I parked my truck in the sun on a 100 degree day for 4-5 hours.
I had a shade in the windshield, and on the driver and passenger doors. Back doors and rear window had the standard factory tint, but no shades.
Normally under those conditions, the truck would have become an oven. I would usually open all the doors and wait a minute or so to let the hot air escape before getting in.
Even then the cab would still be hot for 5 minutes or so with the A/C running at full tilt. After 5 minutes, the in cab temperature would become bearable.
If the trip was less than 10-15 minutes or so, it was a waste of time to even turn the A/C on. This time I got in immediately, started the engine and turned on the A/C.
While the cab was on the warm side of comfortable, it was probably 30-40 degrees cooler than before "Firewall" was installed. Maybe more.
Within 5 minutes I was able to turn the fan down from MAX to the first setting.

When the final coat of "Firewall" is dry. I'll be installing something SecondSkin Audio calls "Overkill-Pro." It's an OEM style foam made of closed cell vinyl infused with rubber.
It's 3/8" thick and is the final layer in my 3 layer system to combat heat and noise. When it's all finished I'll have about 3/4" of insulation inside the cab,
PLUS about another 1/4" to 3/8" as an undercoating outside the cab. All together I figure I'm adding about 100 to 125 lbs to the weight of my truck in insulation.
A great deal of weight and expense. Not to mention all the man hours I've put in installing it. If my truck isn't as quiet as a Mercedes-Benz I'm going to be one PI**ED-OFF guy.