I have used the Dupl-color spray cans of truck bedliner on a few trailers,a truck frame and now my mustang. I like it. It doesn't go on super thick, is durable, easy to apply, and not expensive. It is about $8 per can and I did the underside of my mustang from the firewall aft with 4 cans putting on2coats.

 

A mustang dont have a frame so how you gonna do a frame off.Truck bed lining works great as long as the metal is good and clean no rust por15 is ok but more of a band aid id use a spray on truck bed liner or a true undercoating.

 

All those coatings are thicker than water and will not flow into tiny crevices so you will not achieve a complete coating. If fact you will probably create places for water to collect by blocking drainage paths and small openings (like the corners of the lower shock towers.)

Coatings on bolts, screws, etc., will prevent their being easily removed. They would have to be scraped clean before a wrench would even fit. Personally I wouldn't spray the bottom with anything but paint.

 

Correct, these coatings don't flow into the crevices. But what coating does. Paint doesn't. Rubberized undercoating doesn't. The crevices are sealed as good as possible using seam sealer before any coating is applied.

 

a friend of mine ryno lined the inside and out side of his 76' CJ7 jeep, looks good.. i recmonned it

 

Line-x is sprayed on very hot. Its extremly high pressure system that will get in every little seam. It is actually two liquids mixed together at the sprayer, the material and hardener. If there was any moisture where you are spraying it will be more than gone due to the temp. You just have to be sure to tape off anything that you don't want it in, and you can get it as thick or thin as you want. It is many times better than rhino. It is also dangerous thats why only trained pros can spray it. My friend who sprays told me that the last thing you want to do is accidently spray yourself. Its so high pressure it will cut through your clothes and your skin. If it gets in your body there are ways to save yourself but its so toxic the way my friend explained it to me is, "you have about half a hour to make peace with your God." Its only dangerous during the spraying though, after it hardens its perfectly safe.

 

I was thinking of doing that to my trunk eventually, just to clean the look up, and make it easier to clean up. I agree with remicks about the line-x too, superior product by far

 

If I was going to coat the bottom with one of these materials, I wouldnt do it unless I had the entire floor, trunk floor, frame railings, etc etc replaced. No use coating the old metal which WILL have some rust. Id line the interior side too..

 

This is what I used on mine engine bay under inner floor and roof.
I thinned it a lil with acetone. Seems to be fine hard as a rock looks great to a bit smoother since I sprayed it thru a paint gun.
http://www.eastwoodco.com/shopping/p...iProductID=730http://www.eastwoodco.com/shopping/p...iProductID=730
You can see mine here
http://s208.photobucket.com/albums/bb35/cfzx10/http://s208.photobucket.com/albums/bb35/cfzx10/

 

tech specs also.
http://www.sem.ws/tech_sheet/PT%20TDS.pdfhttp://www.sem.ws/tech_sheet/PT%20TDS.pdf