If I have something that is rusted, I take it apart, and wire brush it
to take off anything loose. Then I use something called Metal Prep by
3M. It is an acid that takes the red rust that is remaining on the
surface and does a chemical conversion of the FeO2 to Fe03. (I think
that is the right chemistry.) The FeO3 is a tightly adhering stable form
of black oxide. It basically kills the rust so it won't keep working
under the paint or cold galvanizing. Then after it all dries for a a day
or so, I paint or cold galvanize as required.
On new stuff that I weld up and don't bother getting hot dip galvanized,
I use the same treatment.
I have a welded up gable bracket mast for the weather radar antenna on
the end of my white house for 5 years now and I don't have any rust
streaks yet.
A word of caution, if you are starting with galvanized material, it will
strip it off, and the resulting mess is a toxic waste due to the heavy
metal contact.
Another IMPORTANT caution: THIS STUFF IS FAIRLY CONCENTRATED ACID. YOU
MUST WEAR GOGGLES AND GLOVES AND SPLASH APRON.
I started using the stuff working in my father's body shop as a kid.
When we would fix a rust spot, (in Iowa we get lots of rusting cars) we
would torch out the old rusted area back to solid metal. Then gas weld
in a piece of new metal (or old hood beat to fit). The weld had to be
completely solid with no gaps or holes. Then we would take a special
spray gun and spray Metal Prep on both the inside and outside till it
dripped on the floor. (Remember, we were doing all of this before OSHA!)
The Metal Prep would neutralize any remaining rust. (It also did a
number on the concrete floor!) We would then bondo fill and paint the
outside and spray tar on the inside.
Before we went to the Metal Prep we had lots of stuff that would show
rust in a year or so. After we went to the metal prep we never had a
complaint.
de n0yvy steve
Rod Fitz-Randolph wrote:
>
> >As I'm usually too cheap to buy stainless, I've recently started
> >on a campain to spray all non-stainless U-bolts with Rustoleum.
> >I try to time the spraying so that the paint is still a bit soft when
> >installed with SS nuts. The nust tend to accumulate a bit of paint in
> >the threads, hopefully seaing the threads in the area of the nut.
>
> Tony, I heartily recommend COLD GALVANIZE by LPS. It comes in a 16 oz.
> spray can, is 95% zinc, conforms to MIL P-46105, MIL P-21035,
> MIL P-26915A, MIL T-26433 Part No. 00516. For identification purposes,
> it comes in a aqua blue can. The Letters "LPS" are bold and in red.
> "Cold Galvanize" is in black letters. It can be sprayed directly on
> a rusted surface and will stop the rust, although common sense says to
> brush the loose, flaky rust off before spraying. It virtually bonds
> with the metal and prevents any rust from starting for years and years.
> It stops active rust dead. I know of no better product to use. It can
> be used as a primer (if you feel the need to paint the object, but it
> sure isn't necessary after "Cold Galv"ing it) It is relatively
> expensive: about $7.00 per can... but one can goes a long way. I have
> seen the results of rusty items sprayed with Rustoleum and I am not
> impressed.
>
> I do not have any stock of LPS or any connection therewith. I am just
> a very, very satisfied user of the product. I purchased it at an ACE
> Hardware store here in Jackson, TN. Good luck with your endeavor.
>
> Rod
>
> Roderick M. Fitz-Randolph
> w5hvv@aeneas.net
> 79 Highland Hills Cove,
> Jackson, TN 38305
> (901) 661-9278 (Phone - after 10 AM and prior to 9 PM)
> (901) 664-7539 (FAX - any time of day or night)
>
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