Painting Fresh Cement Plaster External Wall

8 Oct 2006
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United Kingdom
Hi all

Ive just had a small retaining wall built between us and neighbours (garden wall). Its block and flat and rendered in smooth cement.
Planning on painting sometime soon (have a shower quadrant to fit before the wall) anyway was gonna use very diluted wish wash coat of pliolite paint which I am a big fan of on our house anyway
Its not cheap but seems better and keeps its colour much better than sandtex for me (its white)

So was gonna dilute that paint???

Any other recommendations or thoughts
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I don't know pliolite in particular, but masonry paint and emulsion on plaster, concrete or render need to be well-thinned with water for one or two mist coats.

The mist coats soak in and give good adhesion for later coats. If you apply unthinned paint, the wall will suck the liquid content, and leave the pigments lying on the surface, which does not give good adhesion or long life.

The surface is very absorbent and the first mist coat will practically disappear. The second will soak in but leave the wall coloured. You will know when you have applied enough because the wall will no longer suck the moisture off your brush. Three mist coats may be needed. They are very quick and easy to apply. Try 25% water and mix it in very thoroughly.

If you are using an expensive colour, you can use white paint (which is cheaper) for the mist and first coat.

Once you have killed the suction you can apply unthinned paint.
Although I am a decorator, I have never used pliolite on a retaining wall. I would be concerned about it possibly failing as it won't allow the moisture in the wall to escape. If the builders used waterproof render you may be OK.

Given the extra cost of buying it, I'd recommend calling tech support, eg Johnstones 01924 354354 with regards to suitability for new retaining walls. They recommend using their own Stabilising Solution as a primer but other brands say thin the first coat with white spirit.

Personally, if I were using it, I would use a standard waterbased masonry paint, diluted to 10(?)% as the primer. Any grit pulled out of the render will be easier to sand off before applying the pliolite.
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surely the question is what’s behind the wall.
moisture passing through the wall is going to make a mess of any paint you put on it.
Last cement render I painted in May I used coverstain to prime. Let that cure for 2 full days and painted 2 coats of sandtex. I'd phone technical as advised though

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