I am finally deep into my shower plastering project on the renovation we are doing. 3 showers came out fine with 2 coats of plaster so far. But the 4th shower is driving me mad. There is about a 3 foot circle section of durarock that the lime plaster will not adhere to. We've made 4 attempts at patching it and each time, the next day, the plaster is all cracked and comes right off the wall. The last attempt I used concrete bonding glue on the durarock, but it still did not adhere to it. The lower part of this wall and the adjacent wall is fine.
Any thoughts as to why this is happening and better still, any solutions?

Harvey:-(

sounds like you got some sort of oil stain there...

can you replace the whole section of durarock with a new one?

even if using glue and stuff would "make it stick" what is the guarantee that it wont separate a couple of month from now...

my lime plaster stuff is almost impossible to chisel off the back of the ceramic tile and literally impossible to get off the basecoat...

i would replace the whole section with the stain without thinking twice.

If that is impossible try to soak/wash it with vinegar, but dont blame me if anything goes wrong...

(vinegar breaks fat (look at those skinny english dudes eating all that chips/fish stuff and mcd/burgerking potato eaters... and also vinegar hardens the plaster)