On Thu, 25 Aug 2005 00:29:42 GMT, "R. Zimmerman"
wrote:

It is important to prepare the surface if you expect long life. Wire brush
all surfaces with a cup brush on a angle grinder. Wipe down the surfaces
with a clean rag and paint thinner. Brush on at least two coats following
the instructions on the can. Brushing will always ensure a better bond with
standard enamels because you are stirring the paint onto the surface. When
you spray the paint lands on top of the metal or dirt and you hope it bonds.
The thicker the paint film the better generally so multiple coats are better
than one thick coat. Slow drying oil base paints are better than fast
drying.
On metal parts break all sharp corners with a grinder. A sharp edge does
not hold the paint film so you end up with a very thin layer of paint.
Moisture gets under the paint at the edges and corrosion lifts the paint
film off.
That's is all I can think of. Most people like to blame the paint but any
good paint job is in the preparation. Rustoleum is a good brand but you
will not get as durable finish with a spray can as with a can of Rustoleum
brushed on.
Randy

Whut Randy said, augmented as follows:

The best prep for steel is sandblast, though wirebrush works pretty
well too.

After that, treat with a phosphoric acid based metal prep like Ditzler
579. You'll find that at a store that sells materials for autobody
work. It's about $10 for a quart. You dilute it 2:1 with water for
use, so a quart can treat a lot of metal.

It makes a huge difference. Slosh it on, wait a bit, hose it off.
Rust-Oleum then wets and flows out beautifully and adheres well.

I don't agree that brush is better than spray on properly prepped
metal, but I do agree that paint from a can intended for use with
brush is far better than paint from a rattlecan. I've had very
satisfactory results with Rust-Oleum sprayed on metal treated as
mentioned above and then shot (suitably thinned) with a spraygun.
Cheap import sprayguns work fine with Rust-Oleum.
Use Rust-Oleum thinner. That also seems to make a big difference.

Additional bonus: you can mix colors to get exactly what you want.

I have steel parts thus painted with Rust-Oleum that have been
outdoors for more than a decade with no rust.