> Grant KZ1W wrote:
> Another fix I use is spray zinc "cold" galvanizing as I had to machine
> some custom steel spacers under the base plate for leveling.
Something I have found that works better than "Cold-Galv" is ordinary aluminium
paint, Rustoleum or similar brands. I have found that after a couple of years
rust spots begin to appear through the Cold-Galv, but it takes many years for
aluminium paint to rust through, and it adheres to the metal rarely scaling.
I put my tower up in 1981, using a base insulator I inherited from a fallen
broadcast tower. The end castings were un-galvanised cast steel, covered with
a mixture of rust and red paint. I stripped off the paint and sanded off the
rust, then gave them a couple of coats of aluminium paint. I've had to
re-paint it once in the past 36 years the tower has been up. The hot-dipped
galvanising on the tower shows more rust spots than the aluminium-painted base
insulator castings.
I touched up the freshly cut ends of some galvanised steel straps I used in
another antenna construction project using aluminium paint, and still no rust
after several years. The paint blends in so well with the galvanising that
you would think the whole thing was hot-dipped after it was cut.
You don't have to remove all the surface rust, just the thick or loose scaly
stuff. A thin coat of rust that is still firmly adhered to the metal soaks up
the paint like a sponge soaks up water, and actually makes it adhere better. A
technique sometimes used for painting steel with any kind of paint, is to brush
or spray on a weak acid solution first. After the solution is thoroughly dry,
paint is applied. The thin layer of corrosion helps hold the paint on.
Don k4kyv
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