Sweep! Sweep!

I know, I know, I wrote about curling during the Olympics. But with the Canadian Men’s Curling Championship (a.k.a. the Tim Hortons Brier) currently being decided right here in Regina, did you really think I could choose any other topic this week?

Besides, curling, despite having been around since the 16th century (the first identifiable curling stone, found in Dunblane, Scotland, dates to 1551), is full of scientific interest.

Take sweeping, for instance. Sweeping the ice just in front of a rock makes it travel faster and curl less, because the friction of the broom on the ice causes a thin layer of meltwater to form.

The effectiveness of sweeping is undoubted: it was proved scientifically around a century ago. In those experiments, rocks were slid down an inclined plane covered with ice (so they always slid at the same speed) while either being swept, or not. The experiments proved that judicious sweeping, even with the ordinary corn brooms of the day, could increase the distance a rock could travel by as much as 10 to 15 feet [3 to 4.5 m] over the length of a curling sheet, depending on the condition of the ice surface.

Brooms began their technological advance when, in 1958, Fern Marchessault of Montreal inverted the corn straw in the centre of an ordinary broom to form “the Blackjack,” which, among other things, made an impressively loud sound (and occasionally left an impressive amount of debris on the ice, making sweeping necessary for more than one reason!).

By the time I was covering curling for the Weyburn Review in the 1980s, corn brooms of any kind had mostly given way to “the rink rat,” a three-fingered broom made of a cotton covering over springy pieces of plastic invented by Calgary curling developer Ted Thonger. These made an even more impressively loud sound, and at least theoretically worked better because the cotton covering made more consistent contact with the ice, creating more friction and a more even layer of meltwater.

But the days of the rink rat were numbered even as they became popular. In the late 1960s a pair of Calgary curlers, John Mayer and Bruce Stewart, switched from a broom to a horsehair brush, already favoured by Scots curlers of the day. Today, you only see brushes—though most people still call them brooms (as I have, and will continue to do, in this column).

Brooms can be classified by head type (hair or synthetic), head construction (fixed or pivoting) and handle composition.

A good horsehair head can supposedly cut through frost better than a synthetic head, but frost isn’t usually a big issue in most curling clubs (although there has been some concern about it at the un-air-conditioned Brandt Centre, where the Brier is being played). Synthetic brushes, on the other hand, are cheaper, last longer, don’t shed hairs on the ice, and are easier to clean.

Broom heads can be made of wood, plastic or metal. Fixed heads are firmly mounted to the shaft of the broom. They get the job done and are stable if you’re balancing on them for delivery. However, pivoting heads allow the surface of the head to run flat to the ice for maximum contact regardless of the angle you are holding the handle at. Maximum contact means maximum friction and maximum melting. They also allow curlers to get closer to rocks, particularly in tight areas.

Entry to intermediate level brooms shafts are made out of wood or fiberglass, but wood isn’t recommended because it’s heavy and subject to cracking, splintering or breaking. Fiberglass is strong and can come in a variety of weights, depending on thickness, so it’s the most common.

Aluminum handles are strong, but they can be heavy and cold and are also usually more expensive.

Graphite or carbon fiber composite handles are strong and light. High-content graphite handles are slightly lighter than carbon fiber ones, but they’re also more flexible. Some curlers like that feel, but scientifically speaking, you should be able to transfer more power to the ice with a stiffer shaft, since less energy goes into bending the shaft. Flexibility may also make breakage more likely.

And then there’s the computerized broom Scottish Olympic curling coach Mike Hay had with him to Turin: it measures how hard a curler sweeps, the length of his stroke, and even the temperature of the ice. Hay thinks it may give him the edge in choosing and developing players.

Perhaps. But as you’ll recall, it wasn’t the Scottish men’s curling rink that won the gold medal.

Permanent link to this article: https://edwardwillett.com/2006/03/sweep-sweep/

2 comments

    • Eldon Obach on December 3, 2014 at 9:31 am
    • Reply

    Do you curl? We are having a bonspiel in Wawanesa,MB Feb27-March1 using corn brooms. The brooms are handmade at a small shop in Ontario, and competitors receive one to use in the event, and keep as a souvenir.

    1. I have curled, but not recently! That would be cool to see, though. When I first moved to Saskatchewan corn brooms were all you saw.

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