right lads ive just built a retaining wall down the side of mi garden this week end. im gna finnish it in sto acrylic. i have only ever done it onto the baged render or onto insulation. but im gna render my wall in sand cement. is there any prep i need to do b4 hand to the render or just rub up with plastic float and sponge finish as i wuz gna paint it. cheers