Hi annemolie ............. when you say "dashed", I guess you mean it's rendered and roughcast? .......... ie plastered with a chunky finish?
Yes, it it were bare granite, then sand-blasting (and re-pointing) would look great.
Assuming it's rendered, then it's quite normal to use masonry paint. They're generally non-porous, so no breathability. There's a lot of unecessary worry over this. It rather depends on the construction. Cob should breathe, but stone and rubble construction is really not so sensitive. It depends on how "purist" you want to be.
For "breathability" ............. try "Farrow & Ball" masonry paint (wonderful colours, but expensive,) or, paint made from lime (limewash) to be really "pukka".