Okay, so the coating is punctured, and then moisture gets trapped inside and causes rust because the skin doesn't fall off.

Ever heard of paint capping? Perhaps by another name to you, but what I'm referring to is when rust isn't completely cleaned from an area that's had some pitting, namely the pits themselves. Someone uses a wire brush instead of a sandblaster to clean the rust, and to the naked eye, it looks clean. But then, paint is applied, and instead of penetrating the pits, it "caps" or bridges them, hiding tiny pockets of rust underneath the paint. And guess what? That rust eats away at the metal, underneath the paint, and can cause a lot of damage before it's discovered.

I understand what you're all saying about the undercoat trapping moisture and how it happens. My point is still the same:

1) most likely the surface wasn't properly prepped to begin with, allowing the undercoat to pull from the frame and create the pocket which allows moisture to accumulate.

2) In my limited experience with undercoat, it needs to be applied thick. Or, more appropriately, the final finish will be a thick layer of undercoat, resulting from several thinner layers of application. I can't remember how thick, but more than 1 or 2 layers I'm sure.

3) Undercoat is supposed to "skin" like that for the reason of rejecting road debris. But again, it's performance depends on thickness.

I'm not saying undercoat didn't rot out the frames of your trucks. I'm not saying it didn't create a pocket for moisture to collect. What I'm questioning is, ultimately, why did it happen? What were the circumstances that led to the creation of the pocket? Was the surface improperly prepped? Was the undercoat improperly applied? Was it nice and thick like it should have been except for that one spot that you couldn't quite coat as well as the rest of it because there just wasn't enough room for the right spray angle?

You all say that the undercoat "skin" doesn't tear or flake off when it's damaged.... because it's not supposed to tear or flake off when it's damaged. That's not what it's designed to do. In many cases, the undercoating is "rubberized" and therefore designed to "bounce back" after an impact, which is why it may pull loose from the base before tearing or flaking. Think of dried rubber cement- it does the same thing.

 

well the only rust on the whole truck is the frame, leaf springs and the mounts around them and even then its not even rusted thru its all just chip ed paint and surface rust.. The body itself including the bed doesn't even have surface rust, not even around the wheel wells.. I'll be going to oriellys tomorrow and getting some of the por 15 stuff and the other yall mentioned.. But is there anything I can user this rustoleum undercoating on? Its good sound deadener isn't it? I could spray it on the floor in the interior under the carpet couldn't I?

 

I will give my advice on the situation. Do it. Despite a the risks involved, my dad did it to ours 20 years ago and the frame looks better than many modern trucks on the road today. It definitely paid off. Hell I still have paint in places underneath.

 

how about this idea guys.. I can do the POR-15 idea on the frame and other undercarriage but take the bed to get it Rhino-lined.. I already did the bed but and tailgate so why not do the underneath of the bed too, that wouldn't cause rust its actually good stuff and they would properly prep it too.. I mean my bed is rhino-lined and its tough stuff, real thick too..

 

Please, please, please do not use undercoating. You will regret it in the future. If you want a good durable coating that will look good and last for years, spray on some "Eastwood Rust Encapsulator".

http://www.ebay.com/itm/Eastwood-Rust-Encapsulator-Paint-Flat-Black-Quart-/231074939166?pt=Motors_Automotive_Tools&hash=item35cd23c11e&vxp=mtr
Just buy a cheap HVLP gun from harbor freight and spray it on. I did this over 7 years ago to my truck and everything I have sprayed looks new.



This was taken two weeks ago, over 7 years since I sprayed the frame.

 

Bed liner is a bad idea too. It is designed for BEDS

Use paint(a rust stoping/sealing type)

If the truck is not going to see any weather, then why even think of undercoating it?

 

well would it be okay to use the rustoleum undercoating inside the cab under the carpet as a sound deadener and disperse heat

 

I would do it. But if u are going the route of sound deadner. There is no replacement for it. Look up audio tecnix sound deadner. I used it in my jeep and it really cuts down on the road nosie

 

ive got some extra dynomat from when I did my doors.. So i'll use the rest of tht too

 

ONLY if you like the smell of it!!!!!!! It will take a LONG time for it to quit stinking!!!

 

it'll be sitting for awhile so I can leave the windows down to air out and then im putting new carpet over the top of it

 

Well, have at it..... I was just trying to let you know....... Have fun!!!!!


I'm just glad I will NEVER be riding in it..

I'm just wondering where you found that carpet/sealer.....................

 

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evan i'm reading that as we speak, but here is some pics of the bed and what I've got done so y'all can see what it looks like..

here you can see the half that's been wire brushed and cleaned
http://i1294.photobucket.com/albums/...psc697dc4d.jpg
http://i1294.photobucket.com/albums/...psb04ed169.jpg

 

Guess you didnt powerwash it?

As for undercoat INSIDE, that is abad idea. Any time it is hot(any day over 70) you will get the asphault smell inside.

I would go with a stick on sound deadener