How to treat rust before painting zincalume shed?

dinkydiaussie

I have a zincalume garden shed that the previous owner had put mulch against resulting in rust and some holes at the bottom of one wall. I went to a Bunnings store and was recommended to use Penetrol Rust Treatment on the rust and Selleys 630 Sealant for the holes. The Selleys product was useless as I could not sand it down so I had to dig it all out and rub it down. I have since used Selleys Knead-It with success. I want to paint the shed (as I informed the Bunnings staff member) and was told I could just used Dulux Weathershield after the Penetrol. I have since realised that Penetrol advises using an enamel based primer over it and then I can use a water-based paint after that. I was under the impression that water-based paint such as Weathershield does adhere well to enamel.

Dulux technical staff are suggesting I remove the Penetrol (can't see how I can do that as it soaks into the rust as a rust converter) and use one if their products but this is not feasible.

I just seem to get conflicting advice. I know preparation ia key to a lasting job so before I go any further what should I do?

MitchellMc

Welcome to the Bunnings Workshop community @dinkydiaussie. It's wonderful to have you join us, and many thanks for your question about painting a shed.

Which Penetrol did you use? The Flood Company 300g Penetrol Spraycan, just to treat the rusted section, or Flood 500ml ESP Easy Surface Paint Preparation on the whole shed?

Provided you just spot-treated the rusted areas with the spray, you can overcoat the Penetrol with White Knight Rust Guard Medium Grey Metal Primer Paint, which will then allow you to topcoat with Dulux Weathershield or Taubmans All Weather.

If you primed the whole shed with the ESP, you would need to overcoat it with the White Knight Metal Primer to switch to a water-based product. 

Remember to follow the preparation steps for aged Zincalume for the rest of the shed. Typically, this involves scrubbing it down with a Scotch-Brite pad and Sugar Soap until any trace of a powdery surface is removed from the shed. Flush it down with fresh water after the process to remove any Sugar Soap and wait for it to dry before applying your paint.

Please let me know if you have any questions.

Mitchell