If the old surface is much cracked .
If the old surface blistered no amount of rubbing with pumice will enable the workman to obtain a good ground for the new coats , and it will be necessary to remove the old paint entirely .
If the old surface is much cracked and blistered no amount of rubbing with pumice will enable the workman to obtain a good ground for the new coats , and it will be necessary to remove the old paint entirely .