I have been turning bowls for over 30 years. In the beginning, I used a slide rule to calculate the length of each segment. Now, I have a computer program, much like a C.A.D. program used by engineers to build buildings. Each bowl is one of a kind and completely hand turned. Four coats of food safe salad bowl finish are applied as per FDA recommendations. I have had salad bowls in use for 25 years. Wash with soap and warm water and towel dry. Not for use in microwave, dishwasher, or oven.