Repainting, flaky, paint, concrete windowsills?

[devs]

Hi guys, looking for tips on how to prep and repaint some flaking paint my external concrete windowsills?

I seem to recall using PVA to prime, however, they have failed.

I originally used an oil based Dulux all seasons, but plan to use a water base this time round.

Many thanks

 

[JohnD]

I seem to recall using PVA to prime, however, they have failed.

Never put water-soluble glue on anything that you hope one day to paint.

Scrub it off.

Use masonry paint. Apply one or two thinned mist coats, which will be absorbed and seal the surface

If you got all the glue off.

 

[opps]

As a professional decorator, I get really hacked off when I see people (not you) on the internet recommending PVA as a primer.

PVA, as @JohnD , says will emulsify when wet.

When repairing "sand stone" sills I use SBR as a primer, SBR is twice the cost of PVA but is still a very cheap product.

On new concrete sills, as above, a dilute coat of waterbased masonry paint will suffice as a primer, and no, do not take advice from someone on YouTube with regards to rates of dilution. Just read the back of the tin. If it says, thin by 20%, that is one part water to 4 parts paint.