Further to the last posting regarding whether to sandblast a rear end or not, I decided not to blast it since I wasn't taking it completely apart. Instead, I thoroughly wirebrushed, scraped, and sanded it.

Then before painting it, I used Eastwood Paint Prep in an aerosol can. It supposedly should remove any remaining grease and improve adhesion. After that I put on a coat of Eastwood Rust Encapsulator. When I went out to the garage to put on a coat of Eastwood Chassis Black, I found that the Rust Encapsulator had bubbled and lost adhesion on many spots. Even where it looked good, it came off far too easily with a wire brush.

I also put the Rust Encapsulator on some sandblasted suspension parts and they seem fine. But they didn't get the Paint Prep treatment.

I'm wondering what happened? Is the Paint Prep the problem or did residual invisible grease and oil on the axle cause the problem?

Any experience with this or ideas? I've heard of this happening with POR 15 but not with Eastwood.

David

I'm not sure something was on the metal keeping it from setting up. I blasted mine and used por15 and it looks great and is bullet proof.

David, POR, "Rust encapsulator", Zero Rust and all the other products such as this is like using perfume to cover up body odors smile.gif

They are "Magic potions" and don't "fix" anything, just "encapsulate" that is a marketing term for "cover up" smile.gif How many cans of this stuff would they sell if they called it "Coverup"?

As I have said before, they have their place. Not every car, trailer, truck, tractor, wheelbarrel, lawn mower, bridge, swingset, etc. "Deserves" to be sand blasted, etch primed, urethane or epoxy primed and painted with a SS urethane top coat. So these products are great for some projects.

You just can't expect them to "work" everytime. You are spinning a roulette wheel when you use them.

If you sandblasted the metal clean, applied etch primer, and then epoxy or urethane, it WOULD work. If it didn't you screwed up. You are walking a tight rope trying to cover up rust with one of these products.

Any paint product will fail if the preparation is not adequate. I agree with Martin about not painting directly over rust, but I wouldn't be too quick to dismiss those products. My own experience has been with Por 15 and thus far, I've had few problems with it. But, as Martin said, I don't like to paint directly over corrosion, even though their directions say you can do so by simply removing loose scale and rust. I prefer to remove it completely by sanding, sandblasting, or with scotchbrite discs or a wire wheel in my die grinder. Then I use Por to prevent the rust from coming back. From my personal experience, Por does a great job of preventing recurrence of corrosion, especially when you take the extra step of removing the corrosion alltogether. When you follow the directions and prepare the surface properly, you should have no problems with the end results.

These products do have their place, but their use should be limited to frames, suspension components, interior sheetmetal such as floors and trunk pans, underhood, and the back side of exterior sheetmetal in corrosion prone areas. These products should not be used under exterior paints due to possible adhesion problems.

I have to agree with Randy. I've been using POR 15 to prevent rust on the El Camino so it'll last a few years when I'm done with it. Hopefully this summer. I've uncovered way too much bad bodywork and rust on the car to just fix and hope it won't happen again. I'm also using 3M undercoating on everything the POR doesn't get, like inside the doors, backsides of fenders, etc. Gives me some peace of mind. There's alot of salt air floating around this place, ya know... :D

As far as the original post, I'm unfamiliar with Eastwood's Paint Prep, but anytime I paint a rearend, I'll prep it first, then usually use 1 or 2 cans of brake cleaner to wash it down thoroughly, then follow with my primers and/or paint. I've never had any problems. You might be asking too much of a dual purpose product on gear oil, engine and tranny oils, grease, and brake fluid that are trapped in the paint. JMO, hope it helps.

I guess maybe I did something wrong to my rear-end then. I sandblasted after completely tearing it down. Then used Por-15 exactly the way they say, but I'm not pleased with it at all. It's suppose to be a "satin black" color, but what I ended up with was a powered look and if you just lightly sand it, it appears to be very very thin. :(
What's up with that? :confused:

Did you have problems on the cast iron housing or on the axle tubes?