Take it to the Galv Plant in Palmerston they would take a look for you and can advise what to do. I don't think they stick large Galv items in the Acid anymore so you would have to get it sand blasted which is better for the Zink to stick to anyway. I worked at HB Galv for a couple of years and the boss said the best thing to build boat trailers out of was C Channel and Angle.
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