How to prepare old interiror brick walls for painting

[GrendelsMum]

Hoping that someone on here can offer the usual excellent advice!

As some on here will know, we have an old (listed) house. Some of the walls are old brick. The previous owner had painted them all with modern paint in an unsuccessful attempt to deal with damp. I have stripped as much of the modern paint off the walls as I can manage, and we now have rather tatty bricks with what I guess is flaking distemper on them in a fetching shade of pink.

What's the best way to get the distemper off to a point where it makes a solid base for a new coat of paint?

I'm thinking about sugar soap, hot water and a scrubbing brush.

if it is distemper, hot water will take it off, cold won't. I have taken it off plastered and rendered walls but never off bare brick. No paint will adhere well to distemper.

But I would start with a stiff brush to remove all the loose and flaking stuff. Some of the mortar may come out.

You may have to use a stabilising solution before repainting. Don't put PVA glue on any surface that you hope one day to paint.

I don't know what sort of paint you need to apply, but it will need to be a porous or breathing coating.

Thanks very much, PJ!