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Zinnser Cover Stain - Help!

Discussion in 'Decorating and Painting' started by RichD1, 28 May 2020.

  1. RichD1

    RichD1

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    I’ve stripped back the paint off my 1930’s bay windows and wanted to use an oil based primer as the old wood was in remarkable good condition and still had an oily/resinous texture.

    Zinnser Cover Stain gets good reviews so I thought I would try it. I knotted with Rustins shellac and then started to brush apply the Zinnser.

    Initial impressions was that it was a lot thicker than the reviews led my to believe and when I start to brush it on it felt like it was drying out almost immediately off the brush. You could feel the brush dragging. It was impossible to spread the paint out as this produced lumps which I assume must be paint rolling up. This is now left in the finish and I will have to sand down. The paint was even skinning over in my paint kettle. It seemed to me that it needed thinning by 10% or 20%

    I was not painting in full sun and the window had not been in full sun prior to applying. The air temp was about 16C.

    Is what I experienced to be expected?

    Richard
     
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  3. RichD1

    RichD1

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    Surprised there are no responses. Surely I can’t be the only Zinnser user in the UK!

    Anyway, I rubBed the first coat down and then decided to thinned down my next attempt. So I put a small quantity of Zinnser in my paint kettle and added about 5 to 10% of white spirit. First few brush fulls were encouraging but if you tried to spread the paint out with more than a couple of strokes Backward and forward it still dragged up. Gradually the paint got stiffer and a skin started to form in the kettle again. Put some more thinners in and the same thing happened. I resigned myself to having to sand down after every coat.

    I now have more paint in the tin than when I started!!

    My advice, don’t buy the 2.5L tin but go for the 1L and thin it down by about 50%!

    Let’s hope the final finish will be worth the effort.

    Richard
     
  4. opps

    opps

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    I use a few of their products but have never used that one.

    I only use super fast drying products for things like spot priming, eg water stains on walls where I can roll the finish or where brush marks won't be an issue. I have never come across a rapid drying product that levels off nicely.

    When using oil based paints I normally add Owatrol to help them flow but I am not sure if it will be compatible with Coverstain. You could always email Zinsser (Tor Coatings) and ask
    them.

    Thanks for the heads up though, I shall be avoiding that paint.
     
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  5. RichD1

    RichD1

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    Thanks for your response. I've now flattened the second coat down and now ready for undercoating. On exterior wood do you still use oil-based products? Or do you use an acrylic quick dry for undercoating then oil for the gloss?

    Richard
     
  6. opps

    opps

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    The webpage says "May be used under any solvent-based or water-based topcoat."

    https://www.zinsseruk.com/product/cover-stain/

    I read that as saying that you don't need undercoat. That said, I personally would use oil based undercoat, especially given that gloss paints are particularly good at colour obliteration.

    Oil paints also flow much better than waterbased paints. If you add a little terebene to the paint it will cure faster. It won't affect flow though (which can be improved further with the Owatrol).

    My paint recommendation would be the Dulux TRADE (oil based) Weathershield range. Not cheap but good stuff.
     
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  8. RichD1

    RichD1

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    Thanks, that confirms my thoughts about using oil-based. Just checked the tin of Weathershield Flexible undercoat and it says 2 hour dry time which is good enough for me. Dulux prices have just gone up 5% today. The cost of a litre of Weathershield undercoat is now £30ish. Ouch!!
     
  9. opps

    opps

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  10. RichD1

    RichD1

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    Those are the standard undercoat prices I think. I’ve gone for the Flexible undercoat.

    Just followed your link and it shows a price of just over £25 for the grey which I want to go under a dark colour, unfortunately I needed it today before the rain comes in on Wednesday.

    Richard
     
  11. opps

    opps

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