taikowaza

Hi guys, it's been a while and yotatech is looking great as ever!
I used to live on this site and learned so much. My 4runner runs perfect and I hardly have any issues anymore thanks to how much I learned from all the experts here. Thanks again.

My question is about slider rust. I paid $$$ to Demello Offroad for powdercoated sliders (really beefy, square metal).
Now, I am seeing very clear signs of rust showing through the entire slider (not just where something may have been scratched). I'm talking the whole thing is looking like rust is showing through the powdercoat.

I had thought that getting something powdercoated was solid protection against rust. I never thought rust would start taking over the sliders. Is this normal/expected?
Thanks for any advice and thoughts as to whether I should write Demello about this, or whether sander/rattlecan is my friend. Thanks greatly.

streetlancer

iTrader: (1)

Why?? Why would you powdercoat sliders? What's the purpose of sliders again? To PROTECT your rig! A coat of rustoleum would have sufficed....

RedBeard318

I'm curious as well. My powder coated step bars are extremely rusty and I thought this was supposed to be a durable coating.

Numbchux

Powder coating is definitely not rust-proof. It's tougher than paint, but it can be scratched, and once it does, rust will get under it and it'll come flaking off just like the cheapest paint you've ever seen.

Powder coating sliders is a waste of money. I'm very sorry you learned it the hard way. If they're being used as sliders, they will get scratched, no matter what you paint them with. Best thing you can do is a base coat of POR15, and then rattle can over it. That will help ensure that the scratches won't spread, and will be easy to touch up.

BMcEL

They probably didn't coat the inside of the tubing, causing it to rust from the inside out.

vital22re

iTrader: (2)

Sliders get a lot rock chips and debres that gets kicked up from the front tires. I just sand and apply paint every now and then.

stanz

iTrader: (1)

next time if you want tubes (steps, bumpers, etc) to last, coat the inside with por15 then fill with expandable foam. Seal off the ends with either epoxy or jb weld. I did that on an old ride and had no rusting from the inside out.

The most important thing, however, is maintenance -- touching up scratches, or even the end cap seals I describe above when they get compromised. Otherwise, as you heard above once bare, metal will rust no matter how it's been coated.

waskillywabbit

iTrader: (-1)

Powder coating sliders is about as dumb as giving a pig a bath.

Rustoleum spray paint and be done with it.

:wabbit2:

suncomb1

There are different types of powder coatings. The best and most durable is Epoxy powder coating (mostly industrial). Polyester is what most automotive Powder Coaters use. It has a higher sheen, more color choices but not as durable. Depending on what brand or type of powder coating gun is used will effect the end product. If a Powder Coater uses a Pulse type powder gun then the powder coating will go into corners, angles, etc. better thus supplying better coverage and more consistant coating thickness. Preparation and part temperature is critical to a good powder coating job.You could write a number of books on the ins and outs of powder coating. I would say you received a mass production economical powder coated finish.

After reading some of the comments about powder coating I would like to add that powder coating doesn't come off, it protects metal from rust period and when you drive across a bridge near the ocean feel confident because all of the steel, re-bar and mesh used in the bridge's construction is powder coated. Also you would go through a lot grinding wheels and time if you wanted to take the powder coating off of my trucks frame.

Dickweed

iTrader: (1)

I tried Rino Liner, except for about 4 inches where they weld to the frame. It gives good footing in the dry and holds up well to front wheel rocks. The downside is it peels like a bad sunburn first time you hit something. Regular spray can is your best bet.

4Crawler

iTrader: (3)

Agreed, powder coating is not a good thing for preventing rust. If you think about the process, you sand blast the steel to make it totally clean then you spray on plastic powder and melt it in place. There is no chemical bonding taking place, nothing to passivate the steel surface. So if there is any pin hole (even at the molecular size range) or scratch in the powder, O2 and H2O get in and cause the metal to rust. And it'll keep rusting under the surface as the iron oxide takes more space than the iron it came from, so that expanding rust layer bubbles up the plastic powder coating.

I prefer a good phosphoric acid etch (leaves an iron phosphide layer) then a rust primer and top coat, I use the POR-15 stuff. With that, I'll find that a deep scratch will rust in the exposed steel, but that rust will not spread or bubble up under the rest of the paint, since there is that phosphide layer over the steel and the primer bonds to that and protects the rest of the metal. That gives you time to touch up the rusty scratches, which I probably do once a year.

Now my original sliders that I bought, came powder coated and those had a very thick coating and it did hold up well for the few years I owned them. I did take care to couch up any scratches right away with some primer. But I have even had my t-case cross member, that came powder coated, have the coating flake off with rust underneath. And that part is not exposed to the elements nor to any scratching, might have had a stray piece of gravel fly up and chip it:

Hammerhead 7

Ill add my .02. Yes powdercoating is not bullet proof, Its just another type of coating. I do powdercoating for car and bike builders and one thing that must be done before coating is the surface must be sand/media blasted. A smooth finish will not grip the coating well and not perform well for medium to heavy duty use. And chances are high volume manufacturers dont media blast their parts before coating. Also ive found that the glossy finishes hold up better to corrosion. Ive done some matte finishes and seen them rust from just exposure to moisture. Has something to do with the "Flowing out" of the the glossier finish and results in better coverage. The flat and mattes must leave very small spots exposed which then corrode and lead to rust.

Someone mentioned that it cant be removed...Paint stripper melts it, something like Aircraft Stripper.. Much easier than grinding it off. And the bridges being powdercoated..I dont know about that but i did see that Bridges are being sprayed with Line X now. That was in the Line X brochure...

The best coating in my opinion for durability is a sandblasted surface which is then coated with multiple thinned coats of POR, which really soak into the surface and get embedded there. Then continue a few more coats of non thinned POR and finally a top coat of whatever. I did the frame of my truck this way and whenever i need to do some welding to it I can see the POR in all the pores of the steel as im grinding it off. Enjoy.