How they make curling stones

Now that the U.S. is the Olympic champion in curling, it behooves us to know how the curling stones are made. In fact, all curling stones used in the Olympics are made of granite mined on the uninhabited Scottish island of Ailsa Craig, which itself looks like a granite curling stone sitting in the Firth of Clyde:

The rights to make curling stones from Alisa Craig granite are held by the company Kays of Scotland, and their website (which has a shop where you can buy miniature curling stones, cufflinks, and even granite ice cubes) explains the materials used:

To create the best curling stones you require the finest materials and to this end we harvested 1500 tons from Ailsa Craig of the Common Green Granite and 270 tons of Ailsa Craig Blue Hone so as to satisfy our customers’ demands.

Our Kays Curling stones are made by matching the characteristics of these different granites and combining them enables us to produce the world class competition curling stones.

Over the years our craftsmen have researched the most suitable granites for the various parts of the curling stone.

This extensive research proved that Ailsa Craig Blue Hone granite is the most reliable and proven to be the only EFFECTIVE material for the stone’s running edge on todays modern ice.

The Ailsa Craig 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, all of which badly affect Blue trefor curling stones.

The Blue Hone insert is fitted to the Ailsa Craig Common Green stone body, a technique we have perfected and called “Ailserts”.

The stones weigh between 38 and 44 pounds (17.24-19.96 kg). The brooms are special, of course, and a the members of a pair of curling shoes are different: a “slider shoe” (front) and a “gripper shoe” (back). Who knew?

This video, which I find mesmerizing, shows how the giant granite slabs are transformed into the shiny, spiffy-looking stones you see in competition.

Finally, to show how clueless I am, I found out only this morning, from a comment on this site, that there is women’s curling too. The reason I didn’t know it is because I saw only men’s curling on television, and nobody mentioned women’s curling. Let’s rectify this omission with some footage from the last Olympic championship in Sochi, when Canada took the gold medal by beating Sweden 6-3.  This year  (and I can’t find embeddable video), Sweden took the gold by beating South Korea, the home team, by a score of 8-3 (whatever that means!).

59 Comments

  1. Posted February 26, 2018 at 12:21 pm | Permalink

    Question: since curling is not a sport in which bodily size and strength matters, why would there be separate women’s and men’s curling?

    • Derek Freyberg
      Posted February 26, 2018 at 12:29 pm | Permalink

      And do they use different size/weight stones?

    • Malcolm Morrison
      Posted February 26, 2018 at 12:40 pm | Permalink

      http://www.slate.com/blogs/five_ring_circus/2014/02/14/curling_2014_olympics_do_the_olympics_really_need_separate_men_s_and_women.html

      This explains some differences between the sexes at curling.

      • Posted February 26, 2018 at 1:38 pm | Permalink

        That suggests that physical strength is indeed significant — which surprises me, the women don’t seem anywhere their physical limit in delivering the stones.

      • Posted February 26, 2018 at 1:42 pm | Permalink

        I did not find much explanation in the article, though it describes some important differences. I too am perplexed why women can’t do curling as well, or chess or bowling or snooker, etc.

        One subtle difference might be sweeper to shooter transition. Maybe men are biologically capable of calming their heart rate to focus in shorter times. Could this be from more hunting or battle competitions? I do not know. I would have thought women have just as much if not more capable of recovering their focus after a short active period.

        • Posted February 26, 2018 at 2:34 pm | Permalink

          Chess? Really? If it’s true, maybe aggression has something to do with it. Perhaps same with Curling.

        • BJ
          Posted February 26, 2018 at 10:25 pm | Permalink

          There are a lot of possibilities, and any of the following can be argued in one way or another to have an effect, but I think it’s number five that would actually make a significant difference. Please remember that these are all on average.

          1. Men have more fast-twitch muscle.

          2. Men have faster reaction time.

          3. Men have greater grip strength.

          4. Men have greater endurance, though this difference isn’t as pronounced as most physical differences between the sexes.

          5. Men have better motor skills and spatial reasoning.

          6. Your instinct regarding transition from sweeper to shooter is correct. Men have a lower standing heart rate, their heart rate increases faster during exertion, and their heart rate returns to normal faster.

          With something like chess, better spatial reasoning is an enormous advantage, as chess at a high level requires imagining the board many steps ahead in many different formations. It’s also a matter of a greater number of men than women at the tail-ends of IQ distribution. To get anywhere significant in chess at the international level, one has to be an outlier. Men have greater variability of IQ: there are more men with extremely high intelligence than there are women, but there are also more men with extremely low intelligence. Since intelligence is correlated with success at chess, this is critical, but it should be noted that some of the greatest players ever likely did not have an IQ far above gifted. Bobby Fischer likely had an IQ in the 150’s, but Kasparov was likely in the high 130’s to low 140’s. Still, among the top crop of players, it’s very unlikely that a single person will be anywhere close to average.

          I hope this helps.

          • phoffman56
            Posted February 27, 2018 at 5:36 am | Permalink

            Simply asserting 1 to 6 with no indication at all of evidence, no references, etc. are you?

            For 1 and 3, there is plenty of fairly direct observation, maybe even scientific evidence.

            But I think 4 is probably exactly false, i.e. if any difference, likely women have more endurance. My suspicion relates to sports such as ultra-marathons, which I pay little attention to now. (I did run badly a couple of 50 kms, hardly ultra, so took an interest way back.) But Ann Trason from a decade or two back might have been 3rd in the world, beating all but a couple of men in races over 80 km with significant accumulated elevation gain, despite the men’s likely superior strength and stride length.

            Of course for endurance there might well be differences between 2-3 hour events like marathons, and 8-9 hour events like ironwoman triathlons.

            In my main sport, nordic ski racing, it is clear that strength plays a big role, e.g. in ability to double pole uphill, that being faster than standard striding and kick-double -poling if you can keep that going without ‘stalling at too low speed in too high a gear’. Of course here it’s more strength to weight ratio than just strength. You can rip down the downhills faster as well, if you weigh more and have decent technique.

            I think (strength/stride length) does the same in making men’s marathon records lower than women’s, not endurance.

            I doubt that terribly reliable scientific evidence has ever been produced. The ‘jock-strap’ faculties in universities seem to produce a lot of dubious research–especially on diet.

            Another source of ‘hearsay’ evidence of women’s endurance is accomplishments at Antarctic and major mountain expeditions in recent decades.

        • Posted February 27, 2018 at 12:05 pm | Permalink

          Who says women can’t do curling as well as men? The article specifically disclaims any evidence either way saying

          So while Internet commenters might claim that men’s superior strength means they’d always triumph in a curling battle of the sexes, there’s no entry in the record books that could confirm or deny that theory.

          And the one statistic presented

          As of Thursday evening, the men and the women had each played 23 games. An average of 12.56 points were scored in the men’s games, while the women’s average was 13.08 points.

          is inconclusive.

          • Posted February 27, 2018 at 2:21 pm | Permalink

            Are the layouts they play on the same? Same size targets, etc. By which I mean, all tennis courts are the same for men or women, are all curling matches on the same size ice?

          • Posted February 27, 2018 at 2:25 pm | Permalink

            And now I see that I missed the portion of the thread above with the article quotes. Sorry. They do indeed play on identical surfaces.

    • ladyatheist
      Posted February 26, 2018 at 5:18 pm | Permalink

      Because if a woman is on the team the men won’t pick up a broom!

  2. Mark Sturtevant
    Posted February 26, 2018 at 12:26 pm | Permalink

    How It’s Made is a totally engrossing series. I have often spent a short break from chores to watch an episode of how springs are made, or even drywall, or … whatever.
    The music just goes with it, somehow.

    • GBJames
      Posted February 26, 2018 at 12:41 pm | Permalink

      It is. I saw this particular one a while back and it almost caused me to watch curling on the Olympics this year. But I recovered.

      • mirandaga
        Posted February 26, 2018 at 2:07 pm | Permalink

        Yes, I recovered too–not that I was all that tempted. Maybe I’m missing something, but seems to me they could make the women’s event curling their hair and it would be just about as exciting.

    • Randall Schenck
      Posted February 26, 2018 at 1:03 pm | Permalink

      Yes, How it’s Made is a very interesting series, I think on the science channel. They cover just about everything.

  3. busterggi
    Posted February 26, 2018 at 12:46 pm | Permalink

    “The rights to make curling stones from Alisa Craig granite are held by the company Kays of Scotland”

    Sounds like the Scots Mafia runs the sport.

    • ladyatheist
      Posted February 26, 2018 at 5:18 pm | Permalink

      There’s a Monty Python sketch in there somewhere!

  4. glen1davidson
    Posted February 26, 2018 at 12:54 pm | Permalink

    Clearly a patriarchal process.

    Glen Davidson

  5. Posted February 26, 2018 at 1:01 pm | Permalink

    Ailsa Craig is a volcanic plug, dating back to the (re)opening of the North Atlantic some 60 million years ago. Its unusual microcrystalline structure makes it distinctive, hence its use in curling stones. Erratics from Ailsa Craig show the spread of the ice sheets westwards across Ireland. More at http://nora.nerc.ac.uk/id/eprint/505002/1/Ailsa%20Craig.pdf

    • Jonathan Wallace
      Posted February 27, 2018 at 4:03 am | Permalink

      Ailsa Craig is also notable as the home to around 70,000 gannets (Morus bassanus)as well as a variety of other sea-birds. Eradication of rats on the island has enabled Puffins (Fratercula arctica)and Manx Shearwaters (Puffinus puffinus)to return to Ailsa Craig as breeding birds.
      The island is located in the Firth of Clyde and when the Open Golf Championship is played at Troon it can be seen in the background to some of the tv coverage.

  6. Posted February 26, 2018 at 1:01 pm | Permalink

    Don’t forget about mixed-doubles curling! A new event at this year’s Olympics, games are twice the speed and action as traditional games (that’s not meant to be facetious).

    Congrats to the US men’s team for winning curling gold; they played great. It was a tough Olympics for most Canadian curlers, with both the men’s and women’s teams massively underwhelming. But we won the inaugural mixed-doubles medal via total domination! Watch highlights here: https://www.youtube.com/watch?v=qqXEvKF-lM8

    • nwalsh
      Posted February 26, 2018 at 2:30 pm | Permalink

      And we finished 6 medals ahead of the Americans.

  7. grasshopper
    Posted February 26, 2018 at 1:20 pm | Permalink

    This extensive research proved that Ailsa Craig Blue Hone granite is the most reliable and proven to be the only EFFECTIVE material for the stone’s running edge on todays modern ice.

    A sweeping statement ..
    But MODERN ICE??
    Where has all traditional ice gone?
    Gone to whisky glasses everywhere.

    • Posted February 27, 2018 at 2:27 pm | Permalink

      Perhaps it’s the Zambonis. That creates a very smooth ice. Before Zambonis, the ice was not as uniform perhaps, hence not “modern”? That is a theory which is mine.

  8. phoffman56
    Posted February 26, 2018 at 1:24 pm | Permalink

    “a “slider shoe” (front) and a “gripper shoe” (back). Who knew?”

    IIRC, in olden days, you just wore regular leather-bottomed shoes, but put a rubber (not that meaning!) on the gripper shoe.

    In such pre-historic times, I wore old Eaton’s catalogues under very long socks for hockey shin pads.

    And there was little or no difference between nordic and alpine skis.

    And the difference between nordic and cross-country skiing is that the former uses poles to produce more, sometimes all, speed; whereas the latter uses poles to keep the incompetent from falling on their posteriors.

    And the appearance and 8,000 calories daily of nordic male ski racers is obvious proof that claims of impossibility for avoiding obesity purely by exercise and without diet are bullshit claims.

    And the female nordic champion Margit Bjoergen is the best athlete that ever lived, male or female.

    I could bore you forever–been watching too much boob-tube.

    • busterggi
      Posted February 26, 2018 at 1:51 pm | Permalink

      Why, I remember back when skiers only jumped if someone spilled hot cocoa on them.

      • Mark Sturtevant
        Posted February 26, 2018 at 2:47 pm | Permalink

        Sort of on that note, why are ski jumpers so rail thin? Seems to me that powerful leg muscles would be helpful for the jumping part of ski jumping.

        • Posted February 26, 2018 at 3:41 pm | Permalink

          The lighter weight makes them stay in the air longer as air resistance helps keeps them aloft and I think the timing the jump is more important than power. In fact, some of the rules of jumping are designed so that there is less incentive for skiers to get too light (size limits on the skis for light weight jumpers).

    • barn owl
      Posted February 26, 2018 at 1:57 pm | Permalink

      If I could cross-country ski to work or even just around the neighborhood, I would definitely do so. It’s fun and fantastic exercise. Alas, it rarely snows here. 😦

      • phoffman56
        Posted February 26, 2018 at 6:55 pm | Permalink

        After really big blizzards during my 99 years before retirement, I think 3 times I was able to ski down regular streets to my office. And fortunately, across the street was a pretty big open area to ski in, even a few little hills. Maybe weather or maybe too little outdoors and exercise, but it seems to be waning: Yesterday’s fun race in Parry Sound Ontario had 5 men 70+, but only 4 in each of 60-69 and 50-59.

    • Jonathan Wallace
      Posted February 27, 2018 at 4:38 am | Permalink

      “And the appearance and 8,000 calories daily of nordic male ski racers is obvious proof that claims of impossibility for avoiding obesity purely by exercise and without diet are bullshit claims.”

      What an absurd statement – we all have ‘a diet’ and the amount of fat we carry depends on the balance of energy expended and energy consumed in our diet. Few people in ‘normal’ life can match the intensity, duration and frequency of exercise achieved by elite athletes (even if we had the will power to do so) as we have to do other stuff like sitting at desks, so consequently we have to eat much less if we are to avoid obesity. Controlling what you eat does not necessarily mean doing something faddish like only eating cabbage (or whatever) but if you want to lose weight without paying any attention to the calories you eat you are certainly making things extremely difficult for yourself.

      (And I’m pretty sure that even though they necessarily eat a hell of a lot, those elite nordic skiers control their diets damn tightly).

      • phoffman56
        Posted February 27, 2018 at 5:53 am | Permalink

        See

        If reliable, that counters much you say.

        But we’d need to see some of the ridiculous claims of the diet industry for what I think I’m getting at.

        I’ll grant that those who exercise do pay attention to their tummies telling them they might feel nauseous if they don’t stop stuffing the spaghetti down the gullet. If that’s what you mean by “control their diets”, fair enough. But more likely the control is eating decent stuff, not worrying about the quantity.

  9. nicky
    Posted February 26, 2018 at 1:37 pm | Permalink

    Do you know how eg. our ‘UHT’ milk is made? You don’t want to know, and would not believe it anyway.
    There is a team sport played in Holland and Belgium, where the teams consist in 3 women and 3 men. ‘Korfbal’ a kind of basketball (‘korf’ literally means ‘basket’) or netball.
    It is said it is very old and the precursor of both basket- and netball. Would be nice to have a ‘mixed’ team sport at the Olympics.

    • Posted February 27, 2018 at 11:51 am | Permalink

      I’ve wondered about korfball ever since I got a book of sports rules (massively out of date in many of them now) as a kid. They play it in Germany too, no?

  10. nicky
    Posted February 26, 2018 at 1:37 pm | Permalink

    Do you know how eg. our ‘UHT’ milk is made? You don’t want to know, and would not believe it anyway.
    There is a team sport played in Holland and Belgium, where the teams consist in 3 women and 3 men. ‘Korfbal’ a kind of basketball (‘korf’ literally means ‘basket’) or netball.
    It is said it is very old and the precursor of both basket- and netball. Would be nice to have a ‘mixed’ team sport at the Olympics.

  11. rickflick
    Posted February 26, 2018 at 2:19 pm | Permalink

    Curling is quite interesting, but it makes me nervous to watch it. The shooter has to get the stone within a quarter of an inch of a target stone sometimes. But, what really makes me quiver, is how the sweepers manage to step, slip and stumble their way through a half a dozen stones without actually touching any with their feet. With the result that I’m always watching their footwork and miss the main action.
    I think my favorite thing about curling is to hear a Canadian pronouncing the name of that area down at the end where all the smashing happens. The ‘haouws’.

    • Dave B
      Posted February 26, 2018 at 5:37 pm | Permalink

      what are you talkin’ aboot?

  12. Walt Jones
    Posted February 26, 2018 at 2:22 pm | Permalink

    I heard someone say, “In this day and age, it’s uncomfortable to hear a man yell at a woman, ‘Sweep! Sweep!’”

    • Lars
      Posted February 26, 2018 at 5:29 pm | Permalink

      What’s even more questionable is hearing a woman yell “Harder! Hurry hard!” at a man in public. Or men, given as it’s the skip yelling this.

  13. ploubere
    Posted February 26, 2018 at 2:31 pm | Permalink

    I did find watching curling to be oddly satisfying.

  14. Posted February 26, 2018 at 2:41 pm | Permalink

    I wonder what TSA says about those in your carry on luggage.

  15. Taskin
    Posted February 26, 2018 at 2:59 pm | Permalink

    I curled for a season in high school and enjoyed it despite lack of talent.
    Here’s an interesting video on the physics of curling and the controversy about why the rock curls the way it does.
    m.youtube.com/watch?v=7CUojMQgDpM

    • phoffman56
      Posted February 26, 2018 at 7:00 pm | Permalink

      I did one season too in high school, but I think it was mainly to meet girls. Square dancing was even better for that.

  16. Posted February 26, 2018 at 3:22 pm | Permalink

    As soon as I heard that these stones only come from one place, I had several skeptical thoughts. Considering what happens to these stones during a match, what’s the big deal? I’m guessing some kind of high-tech plastic or ceramic would work better. I’m not buying any shares of Kays of Scotland.

    • Posted February 26, 2018 at 3:43 pm | Permalink

      Aluminum bats would work better than bits of Ash trees, but professional baseball still uses the wooden bats. Tradition is important in some sports, so perhaps that’s why stones come from there?

      • Posted February 27, 2018 at 11:53 am | Permalink

        It also makes records comparable, which is sensible if that sort of thing matters in general.

  17. Ed Collins
    Posted February 26, 2018 at 4:05 pm | Permalink

    So sorry there isn’t more physical contact or nudity to attract the American audience to this great game.
    It’s more like chess or snooker than roller derby.

  18. Lars
    Posted February 26, 2018 at 5:32 pm | Permalink

    Women’s curling is something I’ve been aware of from a very early age, as my mother was a curler and Dad and I had no choice in becoming very well informed of the intricacies of the game.
    Dad said that he was going to paint a blue, white and red bullseye on the kitchen table so that she could demonstrate that day’s plays with the salt and sugar cellars and the sugar bowl.

  19. George
    Posted February 26, 2018 at 7:14 pm | Permalink

    HAAAAAAAAAAARRRRRRRRRRRD!

  20. BJ
    Posted February 26, 2018 at 10:27 pm | Permalink

    I absolutely adore curling. I love watching it. I am not joking. Somehow, I find curling both riveting and relaxing.

  21. infiniteimprobabilit
    Posted February 26, 2018 at 11:05 pm | Permalink

    “The uploader has not made this video available in your country”?

    Wtf???

    Bah!!!!

    cr

    • rickflick
      Posted February 26, 2018 at 11:18 pm | Permalink

      You must be in one of Trump’s SiHt*ehol countries. 😎

  22. Genghis
    Posted February 27, 2018 at 12:15 pm | Permalink

    There is also mixed-sex curling in the Olympics. In fact a Russian man in a mixed doubles event (with his wife) was just found guilty of doping and lost his bronze medal.


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