How to fix accidental application of Ranex Rustbuster on galvanized steel?

[Cranswick]

Hi l applied some Ranex rustbuster on a few  galvanized silver color steel posts under my house that had a little bit of surface rust on them , but l later read the instructions that Ranex is not supposed to be applied to galvanized steel . l think l read it damages the galvanied coating, is that correct?  Is there nothing to worry about or could it have caused some damage, If so what damage could it have done, could the Ranex have stripped away the protective galvanized coating on the posts or even corroded the steel itself . l have noticed some white steaks where l applied the ranex and a slight change is color of the steel. How can l fix it , should l paint the posts with zinc rustguard or galvanized paint, what is the best paint to use. Photo of the silver steel post below below the black beam

[EricL]

Hello @Cranswick 

Welcome to the Bunnings Workshop community. It's marvellous to have you join us, and thanks for sharing your question about using rust converter on your galvanized house post.

The rust converter sometimes works too well, and it begins to affect the galvanized coating. But the repair is relatively straight forward. I suggest using a steel brush to remove all the converted rust and any galvanized coating that might have been affected. Wipe the surface clean and make sure that it is free of oil and grease.

I then suggest using a Cold Galv Spray of your choice. Spray the affected area to restore its primary line of defence.

If you need further assistance, please let me know.

Eric

[Cranswick]

thanks, l will follow your instructions . So the Ranex rustbuster can only harm the galvanized coating of the steel it cannot harm or corrode the steel itself , is that correct. Also regarding the paint do l use Primer glav spray first then topcoat

[MitchellMc]

That's correct, @Cranswick. The Ranex Rustbuster won't harm or corrode the steel. I also doubt getting it on the galvanised posts will pose any real issue. The galvanised coating is quite thick, and I don't believe the product would have got through it and exposed bare steel. Regardless, as @EricL has mentioned, I'd still recommend you re-spray the post with Coldgal if you're concerned.

No primer is required for Cold Gal spray paint as it goes directly onto the steel or previous Gal coating.

Mitchell

[Cranswick]

thankyou, so you think most likely it hasnt damaged the gal coating on the posts, but to be safe l will spray it with cold gal paint, would this be the best one, and l use topcoat not primer. 

[MitchellMc]

That one would be perfect, @Cranswick. Just spray directly over any areas of concern.

Mitchell