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Painting galvanised steel - paint compatibility

Discussion in 'Decorating and Painting' started by dogfonos, 9 Jul 2020.

  1. dogfonos

    dogfonos

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    Would appreciate guidance on an issue of paint compatibility...

    I'm refurbishing old Crittall windows (galvanised steel frames). I intend to paint the frames with Rustins 'quick dry' metal paint, white:

    https://www.rustins.ltd/rustins/our-products/speciality-paints/quick-dry-metal-paint-black

    The Rustin's paint is water-based and can be applied directly to the bare galvanised metal, according to the data sheet. I also have some Johnstone's smooth metal paint in a creamy colour:

    https://www.thepaintshed.com/johnstones-smooth-metal-tinted-colours-cp35192

    The Johnstone's paint is solvent based and doesn't appear to be suitable for painting directly onto a galvanised surface.

    Question is: Can I use the Rustin's paint for the first coat then, when thoroughly dry, apply a final coat (or maybe two) of the Johnstone's metal paint? Or will there be a compatibility problem between a water-based paint and a solvent-based paint? I can roughen the surface of the Rustin's paint to provide a key, if that helps.
     
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  3. opps

    opps

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    Oil based over water based will be fine. Roughing it up is a valid point but I have never experienced any issues when applying OB over WB paints without first providing a key.

    It has been a while since I last painted galvanised metal- the last time I painted a significant volume I used zinc plumbate primer. It is oil based though.options.

    I did paint some galvanised angle bead last year and ending up using what the client/contractor supplied. It was a waterbased product. From memory it was a Hammerite product. It was horrible to work with. I was painting shadow gaps around doors and where the floor tiles meet the wall. The paint didn't flow and attempts to move it over long areas resulted in the paint being dragged.

    Given a choice (and wanting to achieve a high quality finish) I would go for the oil based zinc plumbate primer rather than the waterbased paints. That said, I have used both previously but the WB stuff tends to rip when you try to sand it ,
     
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  4. dogfonos

    dogfonos

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    I should have consulted this forum before buying the Rustin's paint! I'll have to go with what I've got.

    I know what you mean about awkward-to-use paints. Earlier this summer, I painted an old, previously painted metal garage door (washed with sugar soap first) with the Johnstone's oil-based paint. Paint seemed reluctant to spread out and it took ages. The finish looks very good now and seems resistant to knocks. Swings and roundabouts, I guess.

    Thanks for the heads-up. I'll watch out for that.
     
  5. DIYnot Local

    DIYnot Local

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