Here's a spoon I coal burned. I used the instruments pictured: A couple straws, one of Cow Parsnip the other bamboo, a mussel shell scraper, and sandstone and Equisetum to polish and olive-oiled.
This one is about four years old. I like coal burning as a method, esp. while the fire's already going!
A few tricks with coal-burning: as Doc stated, the straw is your guide. A smaller straw is best. Another point is that I burn the bowl
prior to carving out the rough shape of the spoon, as you will find it harder to control after the shape is started. Wiping water will be a good way to establish boundary lines on the width of the burn.
It may be better to carve this one out with a knife, but it is up to you! I don't own a crooked knife, and do most of my carving with knives. To form a bowl with only a knife, I either carve a 'V' down the middle of the bowl area and continue to widen, shaving the walls of the 'V.'
You can also tip drill in the center of the bowl area with a knife and then work it, shaving the walls.....
Good luck!:thumbup: