Painting over Tyrolean render

[GinSoakedBoy]

Hopefully someone can advise the best course of action?

Garage rendered in Tyrolean, previously painted white by previous owners, looked shabby and the paint was flaking off.

I scrubbed this back with a stiff brush and repainted with allcoat. Again over the years this has also started to flake off and look shabby? In a fit of boredom I scrubbed the wall with a stiff brush and again the paint is just flaking away.

Can anyone advise on the best process for painting Tryolean to get a durable / non flakey finish? Is there a step I am missing, paint doesnt seem to want to adhere to the surface. Or what I can coat the walls in to seal whats there after knokcing back the loose stuff to take a fresh coat of paint?

Some images

Thanks in advance

 

[Wayners]

Quick dry stabilizing solution. Will bind and seal surface. Paint may stick better.
Then paint.

Give it a soft biocide wash as well before you prime..
Wall tracer is good or you can hire one.
Other way is hand wash