What is the procedure for sharpening cold-chisels ?

Good answers. I emphasize the need to keep the tip cool. Use water, oil may flame up if you overheat. If you see a blackish colour develop on the tip while grinding, you have over heated it and caused a loss of "temper'". That means that your chisel will get dull very much quicker. The chisel can be re tempered but what a time consuming problem. Don't overheat.