Exterior

[bosquoy]

I'm about to paint the exterior of my house. The walls are rubble built (whinstone) and the original lime mortar has been repointed and repaired over the years with cement, so that it's now mostly cement. The house has been shotblasted so the surface is clean, dry and solid.

I've test painted a couple of areas to see what the finish is like but anything over the lime mortar starts to get a yellow tinge after a couple of weeks. I'm wondering what I should use to prime the lime mortar before slapping on the Sandtex? Cement wash or some sort of sealant?

Any advice would be appreciated.

 

[Munroast]

I had a similar problem on an internal wall where the finish did not really matter. I sorted the problem by painting the lime mortar joints with some diluted PVA. It seemed to work well.

Your doing the outside of a house where the finish and longevity is going to be very very important. Don't take my experience as a solution, and experimenting - do a small are then wait several years - is not at all practical.

 

[bosquoy]

I think I'm coming down in favour of a cement wash. But since it's not a huge area that's affected, I might use brush on some diluted PVA first - can't do any harm!

Thanks for the tip.