I am looking to use some rattle can undercoating on the cab of my truck to help deaden road noise a little. Two things:

1) If I wash the underside and wipe it down with alcohol will this coating last?
2) Is it worth my time or does it not help with noise?

 

The undercoating in spray cans does a decent job of sound deadening the underside of floorpans. The negative side is that it may crack as time passes , allowing moisture to be trapped between the undercoating and metal, therefore promoting rust. A inspection now and again of the underside would catch the cracking , and then a person could just clean and recoat the cracks I guess. A two edge sword of sorts. jmo