History & Manufacture of Curling Stones

By Dave Johnston

Evidence that curling existed in Scotland in the early 16th century includes a curling stone inscribed with the date 1511 found (along with another bearing the date 1551) when an old pond was drained at Dunblane, Scotland and the first written evidence appeared in Latin, when in 1540, John McQuhin, a notary in Paisley Scotland, recorded in his protocol book a curling challenge between John Sclater, a monk in Paisley Abbey and Gavin Hamilton.

By the 1830s, curling had gained so much popularity that the demand for a governing body to regulate the game instilled the creation of the Grand Caledonian Curling Club, presently known as the Royal Caledonian Curling Club (RCCC). This also led to the standardization of the curling stones. Enter the company of T and A Kay begun by two brothers, Thomas Kay and Andrew Kay, who perfected the manufacture of curling stones.

Kays Scotland has been making curling stones since 1851 and is the only company in the world accredited to produce the stones used for Olympic and World Championships matches and has been providing curling stones since the Chamonix Games in 1924. The granite - thought to be some of the strongest and densest ever discovered - is harvested from the island of Ailsa Craig (from Scottish Gaelic fairy rock) roughly once every decade.

Ailsa Craig (from Scottish Gaelic fairy rock), Photo Credit: August Schwerdfeger.

The two materials used are Ailsa Craig Common Green granite and the Blue Hone granite which creates the distinctive characteristics of the curling stones. Ailsa Craig Blue Hone granite is the most reliable and proven to be the most effective material for the stone’s running edge or running band, which is the part of the stone that has contact with the ice. The Common Green Granite is used for the body of the stone because its unique structure is more resistant to heat transfer, it copes better with condensation and does not splinter after contact with another stone in play.

Ailsa Craig is a small island that is 3.2km in circumference and said to have been formed by volcanic eruptions stretching tens of millions of years. As the magma cooled quickly it formed a smooth granite that makes up the surface of the island today. In modern times the island, which sits between Ireland and Scotland, has been the site of a 16th-century castle stronghold, an 18th-19th century prison and, most recently, a bird sanctuary featuring a large array of species including gannets, puffins and kittiwakes.

However, it is the molecular makeup of Ailsa Craig that makes it so uniquely suited to the sport of curling. No other destination in the world produces granite with the blend of heat and moisture resistance and hardy resilience than this small Scottish island.

A second quarry is located in Trefor, North Wales has been a source of the granite used for curling stones due to the limited supply of stone in Ailsa Craig. This location provides the other two variations in colour known Blue Trefor and Red Trefor.

The Curling Stone itself is a combination of two different types of granite. The bottom of the stone is concave so that the outer ring, also known as the Running Band, is in contact with the ice. This minimizes the friction allowing the stone to slide farther. The dull grey band present around the greatest circumference of the stone is the Striking Band that is designed to absorb shock when one stone strikes the other. The entire production process from quarrying to finished stone can be seen here in this Youtube video from the show How it’s Made

Production Supervisor John Brown hand finishes a stone in the workshop.

This March 22nd the SSO will be holding our annual Kilt-up & Curl event. So as your in the hack waiting to make your throw, take a minute to admire the wonderful craftsmanship of the curling stone.