Cracked bowls

Since I guarantee all my salad bowls for life I occasionally get to repair some of the bowls that develop cracks. These cracks are generally from bowls that were dropped and I will always give the owners the choice of replacing or repairing them. I replace very few bowls considering I have made on average 1200 a year since 1994. To my delight many people select to repair them. This gives me a chance to see how they wear and how and why they have cracked. Many of these bowls look better with all the wear. They show a patina of daily life. I have always used butterfly joints to secure the cracks. This would seem to be a natural way to fix these. However, lately I have been repairing them with a metal patch secured with rivets or nuts and bolts.