Hi all,
I'm fabricating some bumper brackets for the truck out of hot rolled
steel.
Do I need to sand ( using those flap disks on the hand grinder) that
hard oxide off before I plaster it with Tremclad, or is it OK just to
paint it as is (just wiped down with laquer thinner)?
It doesn't have to look pretty, as it's just under the truck anyway.
Thanks in advance!

bart wrote:

Hi all,
I'm fabricating some bumper brackets for the truck out of hot rolled
steel.
Do I need to sand ( using those flap disks on the hand grinder) that
hard oxide off before I plaster it with Tremclad, or is it OK just to
paint it as is (just wiped down with laquer thinner)?
It doesn't have to look pretty, as it's just under the truck anyway.
Thanks in advance!

I've painted quite a bit of hot rolled mild steel with scale still on it. It is
better to remove it, but if it's tight and even just prime it and paint it. If
you do decide to remove it, I suggest soaking the parts in (diluted) muriatic
acid, followed by a baking soda rinse, followed by a hot water rinse, followed
by baking at 300°F for an hour if brittleness could even conceivably be an
issue. Then immediately prime (while still warm to the touch if possible) and
let the primer dry and check over the coat for coverage, and recoat if
necessary, then your topcoat. Another good idea is hot-dip galvanizing. Around
here there's a $75US minimum, which will galvanize about 200 pounds of steel,
but it sure does a great job of long-term rust protection. It is possible to use
an etching primer to paint over galvanizing, which may make that the best
possible solution.

But for bumper brackets? Paint it, forget it. :-)

GWE