I'm gearing up to paint my car, and there are a few key areas I intend to coat with truck bed liner for protection, my question is whether or not it would be best to apply the bed liner to bare metal or painted metal, I am stripping the car to bare metal except the non rusted areas of my interior, but I am uncertain whether the bed liner would adhere and protect better on bare metal, or painted. Appreciate any input.

i vote painted, i would be leary of coating bare metal

Bedliner, like any adhesive, adheres to rough texture over smoothe best.Leaving paint is an added barrior tho

That's more or less what I figured, I guess I'm just wondering which is the lesser of two evils, apply to paint that won't adhere as well, but will have better protection, or apply to scuffed bare metal, but have less protection, I'm kind of thinking meet in the middle with non sanded paint, or even primer since its more course I think? Or is it possible to scuff paint up without making it smooth or getting down to metal?

Honestly it wont make a difference, I have a '01 Ram 1500 with Rhyno liner in the bed, I have thrown everything from wood to scrap metal to engine blocks into the the bed and I have not had ANY liner come off yet. Even had river rock dumped in about 20 times in one summer and after a wash it looked like it did on day one. And all they did was rough up the paint in the bed and then spray over it. I would not worry about the stuff coming off, its pretty damn solid.

You're applying undercoat, for the most part. Why would you bother with worrying about how scratched you're making the surface ? The rougher/more coarse the surface is, the better for anything to bond to.

With paint, you're looking for the smoothest surface for paint to lay flat (no scratch marks) and still bond (if outside the chemical bonding window). Who cares how rough the surface is to apply undercoat. You're not applying paint. Grind the s--t with a 36 grit soft disc on a grinder. Bare steel or paint roughed with coarse grit, it's the rough surface to promote adhesion. 20 year old cured paint or bare metal isn't going to mean s--t , unless the paint is peeling from the car itself. Then, you'd want bare steel.

I'm not going to be doing the underbody at this time(doing that in a month or 2 when I put a new floorpan in) I am doing the pass side floor pan, trunk well, and the insides of the fenders(due to rocks kicking up paint isn't really sufficient protection from rust there). I am also painting the car, I am just uncertain as to whether I should paint AND put the truck bed liner on over it, or if I should just take it to bare metal, and scuff it up where I am putting the bed liner. And your post isn't exactly clear on whether I should paint+bed liner, or bed liner directly to bare metal, I want whichever will protect the metal from rust best.

there is no need to paint it and then put bedliner over it. However there isn't a need to pull the old paint off either, just rough it up and spray the bedliner. But remember that rust can start anywhere so if your going to do a piece remember the backside of it too

Alright, thanks for the info, and yeah I realize that, on the fenders its a non issue, since I will be painting the other side at pretty much the same time, the underbody is going to wait till I start automotive school though, so I can use their facilities and equipment to replace my floorpan, but I do indeed plan to coat the underbody with bed liner as well once that's in, not going to use rhino though, if they actually sold it directly instead of applying it themselves I might, but I pretty much do all work on my car myself if at all possible. Planning to use herculiner, looked into it and it got pretty favorable reviews.

Finished


Prepped


Zero rust

A shot of raptor liner in my wells. I grinded all the old unercoat off then painted with zero rust dtm (direct t metal) paint... it has a finish like paint but sticks like primer. The bedliner wasapplied over that. Although itcan be applid to bare metal, this 2 part bedliner works better over primer.

Raptor liner $110 for 4 bottles and hardener
Zero rust $24 per qt

I have seen the spray bedliner used on a dash it looks great,now they can make what ever color you want,his dash was cracked they put some type of tape over the cracks then sprayed it,it looks brand new and will last forever.cost was 200.00
They pulled the dash and installed it back.

After I patched up my floors I coated them first in chassis saver (as the primer) and then scuffed and covered in bedliner (top and bottom). The bedliner I used said it had to go on paint or primer (not on bare metal). Seems to be sticking very well.

5 years from now if they rot out again I am sure I will be cursing the bedliner as I try to weld.... (hopefully it will stop them from rotting...).