How Curling Stones are Made – Video

Originally published in January 2015 for WindyCityCurling.com. Let’s talk about rocks. OK, not those rocks. Stones, curling stones. Here’s the wikipedia entry for curling stones. The curling stone (also sometimes called a rock in North America) is made of granite and is specified by the World Curling Federation, which requires a weight between 38 and 44 pounds (17 and 20 kg) a maximum circumference of 36 inches (910 mm) and a minimum height of 4.5 inches (110 mm).[15] The only part of the stone in contact with the ice is the running surface, a narrow, flat annulus or ring, 0.25 to 0.50 inches (6.4 to 12.7 mm) wide and about 5 inches (130 mm) in diameter; the sides of the stone bulge convex down to the ring and the inside of the ring is hollowed concave to clear the ice. This concave bottom was first proposed by J. S. Russell of Toronto, Canada sometime after 1870, and was subsequently adopted by Scottish stone manufacturer Andrew Kay.[9] The granite for the stones comes from two sources: Ailsa Craig, an island off the Ayrshire coast of Scotland, and the Trefor Granite Quarry in Wales. Ailsa Craig is the traditional source and produces two types of granite, Blue Hone and Ailsa Craig Common Green. Blue Hone has very low water absorption, which prevents the action of repeatedly freezing water from eroding the...

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