The World Bowls Stamp was introduced in 2002.A current stamp is a requirement for the bowls to be valid for use in major competitions under the control of World Bowls.
Law 8.2 states that for domestic play, Member National Authorities can decide the requirements for re-testing and re-stamping bowls. Bowls Canada Boulingrin is the Canadian National Authority. Conditions of Play for the various Canadian National Championships indicate bowls inspections will be performed. Examples include:
At the Canadian Junior Championships bowl and shoe inspections shall be conducted prior to each game.
At the Majors a bowl and shoe inspection shall be staged prior to the start of the competition.
World Bowls requires that licensed manufacturers and licensed testers put the registered 'World Bowls Stamp ' either on the small end or between the inner and outer rings of the bowl.
According to bowls tester Pershore Bowls Centre, there are only 9 standardized bowls testing tables in the world - five of them in Australia and four in the UK. World Bowls maintains a list of bowls manufacturers and testers
In the following video Mark Hensell, Production Manager for Henselite, is interviewed regarding the standards for the manufacture of lawn bowls. The procedure for testing bowls is covered.