Water down masonry paint as primer? (Photo)

[brooky_agb]

Hi all!

I have channeled out some exterior render to hide TV cables which I cemented back over the top.

Before I paint over it with masonry paint do you think it's ok to prime it with watered down masonry paint?

If so what ratio of water to paint should I use? (I have Sandtex paint)

If not should I be using something else? You can actually see a repaired corner that wasn't primed and looks terrible some years later.

 

[JohnD]

I certainly do

Walls are often very hungry so I usually apply (at least) two well-thinned mist coats. Start with 50/50. You will know you have killed the suction when it no longer sucks the moisture off your brush.

If the thinned paint disappears into the surface, you know it needs misting again.

You could give your previous repair a stiff brushing to remove any flaky material and mist it again.

 

[brooky_agb]

Many thanks John!