What kind of paint to use on concrete blocks (Exterior)?

It sounds like you are talking about cinder blocks.





If they are new you want to let them dry out for about 10 good drying days,this is so the mortar joints dry.





For a good appearance you then want to use a block filler-that's a thick paint especially made to fill in all the pores and pin holes in the block.Block filler is best applied with a thick(1 inch +)roller cover and worked in to make sure all the holes are filled.It can also be sprayed using a very high quality airless sprayer with a large tip-a small airless simply wont push that thick paint.





For a finish coat you have two choices-Regular exterior LATEX house paint,any shine you want or an Elastomaric coating-the house paint being the more cost effective way as Elastomaric is costly-you can roll or spray either,just like the block filler-Be care full spraying or you could wind up trashing cars,etc....





If there is already paint on the block simply scrape it,watch out for any powdery areas-get that off real good.Prime all the bare spots with a good acrylic primer and paint with acrylic(latex) house paint.What kind of paint to use on concrete blocks (Exterior)?
On our external windowsills we have used weathershield smooth exterior masonry paint. Dulux. It still looks good and May hasn't been the sunniest month here in Hampshire UK! (Rain and wind actually)! ):