painting new pre cast concrete window sills

ednwireland

got masonary paint peeling off the sills, the surrounds whcih are render are fine its just the pre cast sills, is there a primer or binder or something or do i just paint them every year ?

jack of all

You could try an alkali resisting primer (Dulux do one) or a stabilising primer, suitable for painting on cement based backgrounds.

builditwell

I prepared them by rubbing them up with very rough sand paper, then 2/3 good coats of polybond. I used oil based paint instead of masonry, 2 undercoat and 2 gloss. I think it waterproofs the cills much better. Originally on the back of the house they were masonry to match the reveals but found it flaked off in no time at all.

Regards
Buildtwell

Juwwi

Scrap as much of the old paint off as possible and then get some stabilising primer .

woodies sell a water based one in 2.5 litre tins..

its very watery so be carefull when using it it can be messy.

give it a coat of the stabilising primer then 2 coats of masonary paint.


( oil based undercoat and gloss isnt suitible for concrete it says on the tin for wood and metal )

leprecawn

HI. I have been painting my concrete precast windowsills every 2 yrs or so with masonary paint, and it eventually flakes off in patches . While visiting my friend, a tiler , I noticed that his was lovely and smooth and he said he uses undercoat and gloss. Tried it on one windowsill , and now i am removing masonary paint from the other 2 one year later and the one i did with gloss is still fine, so dont mind what it says on the tin, it works. Just remember you must fget all the old paint off down to the bare concrete. I use a paint scraper . its boring but it gets it all. Nitromors will also work but will leave a light coat that will need sanding. The only thing that i have notmanaged to solve so far is the tiny holes that are prevelant in precast windowsills. There must be a permanent way of filling these. If anybody knows , please post solution.(dublin diy guy)

robfin77

hi try iso pond