I am a plasterer but havnt done much rendering.I contacted celcon with regards to rendering their blocks and they told me to render 6:1 wich i know is weak but what they said made sense. "the mortar shouldnt be stronger than the material". This also applies to brick work. I wetted the wall applied the render and then wetted the render during drying process but after 4 days i can scratch the render off with my fingers. If i then went over this with a topcoat would it be ok or does it all need to come off and ignore what celcon have said and use a stronger scratch coat? any help would be appreciated