To create a stippled effect on ceilings, first paint the ceiling with a proprietary plastic compound. Then wrap a plastic bag tightly around a sponge and, while the compound is still wet, bounce the bag gently on the ceiling. On each bounce the bag pulls at the compound and leaves an attractive stippled effect.
Wards, make more chisel cuts every 3mm. Stop 3mm short of the end of the final cutting line. Reverse the chisel so that its bevelled edge is facing in towards the centre of the mortise and make similar cuts from the middle in the opposite direction, again stopping 3 mm short. Chop out the cuts with the bevelled edge of the chisel facing downwards, and continue as before with vertical cuts to the required depth. Finally, cut away the 3 mm of timber left at each end of the mortise.