How to bond dry-cast rough-casting prior to painting?

[jsstevenson]

Hello...

Nearing completion of building a house and I asked the roughcaster to provide a wet cast render (west coast of Scotland). Using grey cement and 6mm granite chips he chose to apply a drycast (pebble-dash)! Putting aside my anger at this I now have a situation to somehow fix, unless I want a cement grey house!

How can I paint a drycast? If you are familiar with drycast you will know that a brush of your hand over drycast dislodges the chips, so it is clearly an awful base for painting. Also if it is painted as it is then it will very soon have grey 'dots' all over it as the chips fall off due to weathering and so forth. Does anyone know of a material/product that could be applied to the drycast to somehow help bond the granite prior to painting?

Obviously if I had wanted a drycast I would have used white cement and a decorative chip but as I say I instructed a wetcast finish!

Thanks for any suggestions.
Jamie.

 

[roughcaster]

Painting over dry cast/dash (roughcasting) "never looks good". It has a totally different texture/finish to the wet dash. Even though wet dash has a rough looking texture, it has a "closed up" surface finish, and will accept coats of paint without leaving holes, if you know what I mean.. "A painted wet dash wall looks nice"..... Painting over dry dash,,, because of it's "open" surface finish will show up any weathering that takes place, ie, loose chips falling off etc, plus,,,, as I said, the different surface finish. You will always be able to tell a painted wet dash wall, from a painted dry dash wall..... A dry dash/roughcasted surface is not meant to be painted over. The colour of the cement background and the coloured decorative chips are the features of dry roughcast. A well roughcasted wall with complimenting colours, against stonework/brickwork, looks superb. Sure you'll get some weathering early on,(loose chips falling off) but that normally settles down. It's self cleaning too,,,, unlike a painted surface.

Roughcaster.

 

[PT1967]

You could try using a stabalising primer though I think this would have to be sprayed as brushing will knock off chips. Why not try in a small area.