Mark, The foam I was looking at, is called Great Stuff and is sold by Dow Chemical. The part below is the info off their website describing the difference between "open cell" and "closed cell" foams. Although they don't say water proof, I sprayed this stuff into a piece of frame rail, let it dry, weighed it and then dumped it into water over night. The next day, after blowing off the outside, the part weighed the same as before, indicating that it did not pick up any water. I think there are some cautions. If the foam oozes out of areas, it should be wiped off before it dries, so that you get that tough skin that forms. After it dries, you can cut it off with a knife, but I think it opens up the "pores" and might allow water penetration. I'm not advocating that anyone else do this but I feel comfortable enough with what I've seen to use it on my car. I'm going to put it in the frame rails, behind the rear wheel cavity (between the outer fender and inner fender) and the door sills. If I'm still around in 10 years I'll update what happened. Be advised that this is NOT a daily driver (more a sunny day in the summer driver) and so no matter what I do, I don't think it will radically affect the outcome. Also, for those asking about bedliner for the interior of their cars, I used it on my car and was quite pleased with the result. That stuff is tough as nails and sticks hard. I then used 2 layers of roofing membrane for sound deadener. That's a product that they use to seal a leaky roof and comes in sheets about 1/8 in thick. Two layers gave me about 1/4 in of sound relief. The only thing with that is, I wouldn't want to have to remove it to do work on the car. Cheers, Don 1970 AMX "The older I get, the better I was." There are two key differences between latex foam and GREAT STUFFT, which is a polyurethane foam: 1.. Latex foams are typically "open cell" and, as a result, can take on water. In fact, the same properties that allow you to wash latex foam off your hands with water also mean that the cured foam can absorb water. This can cause wood rot or deterioration in areas where wet latex foam is next to wood, such as a window frame. In contrast, GREAT STUFFT is a closed-cell foam. It forms a water-resistant outer coating when cured. ----- Original Message ----- From: <Wrambler242@xxxxxxxxxxx> To: "Don" <don_nsx@xxxxxxxxxxxx>; "AMC/Rambler owners, drivers and fans." <amc-list@xxxxxxxxxxxx> Sent: Thursday, December 20, 2007 11:13 AM Subject: Re: [Amc-list] Bedliner/foam in rails > I'll bite. > Exactly which foam are you looking at? > Even marine purposed stuff I have seen says that if the outside surface is > penetrated it must be sealed with a sealer or it will absorb water! > The shiny outercoating is the water proof area. Internally it is not so > great. > A true waterpoof foam I would be interested in seeing a link too! > > -- > Mark Price > Morgantown, WV > 1969 AMC Rambler, 4.0L, EFI, T-5 > 2004 Grand Cherokee Laredo, 4.7L, Quadratrc II > " Chronic Pain Hurts" > > -------------- Original message ---------------------- > From: Don <don_nsx@xxxxxxxxxxxx> >> Frank, >> Okay, I hear you loud and clear on the foam, but is this something that >> we know >> instinctively or is there some research and history behind it. >> The foam I'm talking about is meant to seal moisture OUT. Moisture does >> not >> penetrate it. You can submerge it in water overnight and take it out and >> cut it >> in half and its dry as a bone. It also sticks to whatever material it is >> touching like baby @(*%#! to a blanket. >> My guess, is that, if your panel is dry, it shouldn't be a problem. >> I think I will try to talk to the people who make the stuff and see what >> their >> testing tells them. >> Don >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: >> http://www.amc-list.com/pipermail/amc-list/attachments/20071219/1784f58b/attachm >> ent.htm >> _______________________________________________ >> Amc-list mailing list >> Amc-list@xxxxxxxxxxxx >> http://www.amc-list.com/mailman/listinfo/amc-list > _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://www.amc-list.com/mailman/listinfo/amc-list