Repointing internal walls where mortar is turning to dust.

[Clm.forest]

Hi all, we are currently in the process of repointing some of our internal walls after removing gypsum and some lime plaster.

The house is thought to have been built around 1850-1900

I have made a start on one wall using lime putty mortar from lime stuff so far to test out. The original mortar is basically dust. I have started from the bottom of the wall because there are some loose bricks further up. Is this the best way? There are a fair few loose bricks in the walls around the house. When I am raking out I am being careful not to go too deep. It just seems like if I brush the wall with a brush the mortar just falls out! We have been on a course for re pointing but the walls we were shown one weren’t quite in this state. I am making sure to rake out deeper than the joint width but will it even set if the old mortar is dust behind it?

Unfortunately externally the house has been repointed with cement. We plan to tackle the external next year but we had focusing on the inside for now.

Any advice is much appreciated. Learning as we go.

 

[stuart45]

Rule of thumb for raking out the joints is double the joint width. Make sure the wall is well damped down. You don't want too much water being sucked out of the mix. Ideally, the surface should be reasonably dry or it will run down the facework, but below the surface should be damp.
What you've done so far is looking good. Normally you start at the top though.