Editing Curling (section)

== Equipment ==
[[File:curlingsheet.jpg|thumb|The playing area in curling is shown here. Stones must land between the ''hog line'' (bottom of photo) and the ''back line'' (behind the rings) and may not contact boards or out lines (on the sides) at any time during travel.]]

=== {{anchor|Curling sheet}}Curling sheet ===
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[[File:CurlingHouseAndBackline.svg|thumb|Detail of the curling sheet. The 12-foot circle covers the backline.]]
The playing surface or ''curling sheet'' is defined by the [[World Curling Federation]] Rules of Curling.<ref name="Rules">{{Cite web |date=October 2022 |title=The Rules of Curling and Rules of Competition |url=https://worldcurling.org/competitions/rules/ |access-date=2023-06-15 |website=World Curling Federation}}</ref> It is a rectangular area of ice, carefully prepared to be as flat and level as possible, {{convert|146|to|150|ft}} in length by {{convert|14.5|to|16.5|ft}} in width. The shorter borders of the sheet are called the backboards.

A target, the ''house'', is centred on the intersection of the ''centre line'', drawn lengthwise down the centre of the sheet and the ''tee line'', drawn {{convert|16|ft}} from, and parallel to, the backboard. These lines divide the house into quarters. The house consists of a centre circle (the ''button'') and three concentric rings, of diameters 4, 8, and 12 feet, formed by painting or laying a coloured [[Vinyl composition tile|vinyl]] sheet under the ice and are usually distinguished by colour. A stone must at least touch the outer ring in order to score (see [[#Scoring|Scoring]] below); otherwise, the rings are merely a visual aid for aiming and judging which stone is closer to the button.
Two ''hog lines'' are drawn {{convert|37|ft}} from, and parallel to, the backboard.

The ''hacks'', which give the thrower something to push against when making the throw, are fixed {{convert|12|ft}} behind each button. On indoor rinks, there are usually two fixed hacks, rubber-lined holes, one on each side of the centre line, with the inside edge no more than {{convert|3|in}} from the centre line and the front edge on the hack line. A single moveable hack may also be used.

The ice may be natural, but is usually frozen by a refrigeration plant pumping a [[brine]] solution through numerous pipes fixed lengthwise at the bottom of a shallow pan of water. Most curling clubs have an ice maker whose main job is to care for the ice. At the major curling championships, ice maintenance is extremely important. Large events, such as national/international championships, are typically held in an arena that presents a challenge to the ice maker, who must constantly monitor and adjust the ice and air temperatures as well as air humidity levels to ensure a consistent playing surface. It is common for each sheet of ice to have multiple sensors embedded in order to monitor surface temperature, as well as probes set up in the seating area (to monitor humidity) and in the compressor room (to monitor brine supply and return temperatures). The surface of the ice is maintained at a temperature of around {{cvt|23|F}}.<ref name="branch">{{cite news |url=https://www.nytimes.com/2009/08/17/sports/17curling.html |last=Branch |first=John |title=Curlers Are Finicky When It Comes to Their Olympic Ice |work=The New York Times |date=17 August 2009 |url-status=live |archive-url=https://web.archive.org/web/20171006062707/http://www.nytimes.com/2009/08/17/sports/17curling.html |archive-date=6 October 2017}}</ref>

A key part of the preparation of the playing surface is the spraying of water droplets onto the ice, which form ''pebble'' on freezing. The pebbled ice surface resembles an orange peel, and the stone moves on top of the pebbled ice.<ref>{{cite press release |url=http://www.twincitiescurling.org/press_release/usa_today_021704.html |title=USA-Today: Curlers Play Nice and Leave No Stone Unturned |publisher=Twin Cities Curling Association |url-status=dead |archive-url=https://web.archive.org/web/20120902063305/http://www.twincitiescurling.org/press_release/usa_today_021704.html |archive-date=2 September 2012}}</ref> The pebble, along with the concave bottom of the stone, decreases the friction between the stone and the ice, allowing the stone to travel further.<ref>{{Cite web|url=https://www.smithsonianmag.com/innovation/why-curling-ice-is-different-than-other-ice-180949752/|title=Why Curling Ice is Different Than Other Ice|last=Hendry|first=Erica R.|website=Smithsonian|language=en|access-date=2019-05-10|archive-date=10 May 2019|archive-url=https://web.archive.org/web/20190510182636/https://www.smithsonianmag.com/innovation/why-curling-ice-is-different-than-other-ice-180949752/|url-status=live}}</ref> As the stone moves over the pebble, any rotation of the stone causes it to ''curl'', or travel along a curved path. The amount of curl (commonly referred to as the ''feet of curl'') can change during a game as the pebble wears; the ice maker must monitor this and be prepared to scrape and re-pebble the surface prior to each game.<ref>{{cite web |url=https://www.nbcnews.com/id/wbna35537168 |title=Smooth operators: They make Olympic ice nice |date=23 February 2010 |publisher=[[MSNBC]] |work=Today in Vancouver |url-status=live |archive-url=https://web.archive.org/web/20121004155357/http://today.msnbc.msn.com/id/35537168/ns/today-today_in_vancouver/t/smooth-operators-they-make-olympic-ice-nice/ |archive-date=4 October 2012 |access-date=12 August 2011 }}</ref>

{{wide image|Curlingsheet flip.svg|800px|3=<div style="text-align:center;">A curling sheet, with dimensions in feet (<nowiki>1' = 1&nbsp;ft = 0.3&nbsp;m</nowiki>).<br/>'''CL:'''&nbsp;Centreline{{•}} '''HOL:'''&nbsp;Hogline{{•}} '''TL:'''&nbsp;Teeline{{•}} '''BL:'''&nbsp;Backline{{•}} '''HA:'''&nbsp;Hackline with Hacks{{•}} '''FGZ:'''&nbsp;Free Guard Zone</div>}}

=== Curling stone ===
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 {{convert|44|and|38|lb|2|order=flip}}, a maximum circumference of {{convert|36|in|0|order=flip}}, and a minimum height of {{convert|4+1/2|in|0|order=flip}}.<ref name="Rules"/> The only part of the stone in contact with the ice is the ''running surface'', a narrow, flat annulus or ring, {{convert|1/4|to|1/2|in|order=flip}} wide and about {{convert|5|in|order=flip}} in diameter; the sides of the stone bulge convex down to the ring, with the inside of the ring hollowed concave to clear the ice. This concave bottom was first proposed by J. S. Russell of Toronto, Ontario, Canada sometime after 1870, and was subsequently adopted by Scottish stone manufacturer Andrew Kay.<ref name="x"/>

{{multiple image |align=right |total_width=350
 |image1=curlingrock.jpg |caption1=The curling ''stone'' or ''rock'' is made of granite
 |image2=Curlingstoneold.JPG |caption2=An old-style curling stone
}}

The granite for the stones comes from two sources: [[Ailsa Craig]],<ref>{{cite web|url=https://www.kaysscotland.com/ |title=Kays Scotland: Olympic Curling Stones |publisher=Andrew Kay & Co |access-date=January 31, 2025}}</ref> an island located in the [[Firth of Clyde]] off the [[Ayrshire]] coast of Scotland, and the [[Trefor, Gwynedd|Trefor]] Granite Quarry, North of the [[Llŷn Peninsula]], Gwynedd in [[Wales]]. These locations provide four variations in colour known as ''Ailsa Craig Common Green'', ''Ailsa Craig Blue Hone'', ''Blue Trefor'' and ''Red Trefor''.<ref>{{Cite web|url=https://glennpaulley.ca/curling/2020/03/07/curling-stones-taken-for-granite/|title=Curling stones: taken for granite – Throwing Stones|first=Glenn|last=Paulley|date=7 March 2020 |access-date=28 February 2023|archive-date=28 February 2023|archive-url=https://web.archive.org/web/20230228164420/https://glennpaulley.ca/curling/2020/03/07/curling-stones-taken-for-granite/|url-status=live}}</ref>

''Blue Hone'' has very low water absorption, which prevents the action of repeatedly freezing water from eroding the stone.<ref>{{cite web |url=http://www.anchoragecurling.com/evolution.htm |publisher=Anchorage Curling Club |title=About Curling/Stones |access-date=4 August 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120415082409/http://www.anchoragecurling.com/evolution.htm |archive-date=15 April 2012}}</ref> ''Ailsa Craig Common Green'' is a lesser quality granite than ''Blue Hone''. In the past, most curling stones were made from ''Blue Hone'', but the island is now a wildlife reserve, and the quarry is restricted by environmental conditions that exclude blasting.

[[Kays of Scotland]] has been making curling stones in Mauchline, Ayrshire, since 1851 and has the exclusive rights to the Ailsa Craig granite, granted by the [[Marquess of Ailsa]], whose family has owned the island since 1560. According to the [[United Kingdom Census 1881|1881 Census]], Andrew Kay employed 30 people in his curling stone factory in Mauchline.<ref>{{Cite web |url=https://www.scotlandspeople.gov.uk/view-image/nrs_census_lds/2031358 |title=1881 Census entry for Haugh, Mauchline, Ayrshire GRO Ref Volume 604 EnumDist 1 Page 3 |website=Scotland's People |access-date=19 February 2018}}</ref> The last harvest of Ailsa Craig granite by Kays took place in 2013, after a hiatus of 11 years; 2,000&nbsp;tons were harvested, sufficient to fill anticipated orders through at least 2020. Kays have been involved in providing curling stones for the Winter Olympics since Chamonix in 1924 and has been the exclusive manufacturer of curling stones for the Olympics since the [[Curling at the 2006 Winter Olympics|2006 Winter Olympics]].<ref>{{cite web |url=http://www.kaysofscotland.co.uk/news.php |title=News |publisher=Kays of Scotland |access-date=4 August 2012 |url-status=dead |archive-url=https://web.archive.org/web/20130226221740/http://www.kaysofscotland.co.uk/news.php |archive-date=26 February 2013}}</ref><ref>{{cite web |url=https://canmore.org.uk/site/320218/mauchline-9-barskimming-road-kays-curling-stone-factory |title=Mauchline, 9 Barskimming Road, Kay's Curling Stone Factory |publisher=Canmore |access-date=19 February 2018 |archive-url=https://web.archive.org/web/20180219210813/https://canmore.org.uk/site/320218/mauchline-9-barskimming-road-kays-curling-stone-factory |archive-date=19 February 2018 |url-status=dead }}</ref>

''Trefor'' granite comes from the Yr Eifl or Trefor Granite Quarry in the village of Trefor on the north coast of the [[Llŷn Peninsula]] in [[Gwynedd]], [[Wales]] and has produced granite since 1850. ''Trefor'' granite comes in shades of pink, blue, and grey.<ref>{{cite web |url=http://www.museumwales.ac.uk/media/518/welsh_stone_forum_oct_04.pdf |title=Welsh Stone Forum newsletter |date=October 2004 |access-date=26 January 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140202113949/http://www.museumwales.ac.uk/media/518/welsh_stone_forum_oct_04.pdf |archive-date=2 February 2014 }}</ref> The quarry supplies curling stone granite exclusively to the Canada Curling Stone Company, which has been producing stones since 1992 and supplied the stones for the [[2002 Winter Olympics]].

A handle is attached by a bolt running vertically through a hole in the centre of the stone. The handle allows the stone to be gripped and rotated upon release; on properly prepared ice the rotation will bend (''curl'') the path of the stone in the direction in which the front edge of the stone is turning, especially as the stone slows. Handles are coloured to identify each team, two popular colours in major tournaments being red and yellow.
In competition, an electronic handle known as the [[Eye on the Hog]] may be fitted to detect hog line violations. This electronically detects whether the thrower's hand is in contact with the handle as it passes the hog line and indicates a violation by lights at the base of the handle (see [[#Delivery|''delivery'']] below). The ''eye on the hog'' eliminates human error and the need for hog line officials. It is mandatory in high-level national and international competition, but its cost, around [[United States dollar|US$]]650 each, currently puts it beyond the reach of most curling clubs.

=== Curling broom ===
{{more citations needed section|date=August 2014}}
[[File:Curling broom.png|thumb|left|Curling broom]]
The ''curling broom'', or ''brush'', is used to sweep the ice surface in the path of the stone (see ''[[#Sweeping|sweeping]]'') and is also often used as a balancing aid during delivery of the stone.

Prior to the 1950s, most curling brooms were made of corn strands and were similar to household brooms of the day. In 1958, Fern Marchessault of [[Montreal]] inverted the corn straw in the centre of the broom. This style of corn broom was referred to as ''the Blackjack''.<ref name="curling.ca">{{cite web |url=http://www.curling.ca/start-curling/the-history-of-curling/ |title=The History of Curling |publisher=[[Canadian Curling Association]] |date=18 January 2013 |access-date=10 February 2014 |url-status=live |archive-url=https://web.archive.org/web/20140210004409/http://www.curling.ca/start-curling/the-history-of-curling/ |archive-date=10 February 2014}}</ref>

Artificial brooms made from human-made fabrics rather than corn, such as the ''Rink Rat'', also became common later during this time period. Prior to the late sixties, ''Scottish'' curling brushes were used primarily by some of the [[Scottish people|Scots]], as well as by recreational and elderly curlers, as a substitute for corn brooms, since the technique was easier to learn. In the late sixties, competitive curlers from [[Calgary]], Alberta, such as John Mayer, Bruce Stewart, and, later, the world junior championship teams skipped by [[Paul Gowsell]], proved that the curling brush could be just as (or more) effective without all the blisters common to corn broom use.<ref name="curling.ca"/> During that time period, there was much debate in competitive curling circles as to which sweeping device was more effective: brush or broom. Eventually, the brush won out with the majority of curlers making the switch to the less costly and more efficient brush. Today, brushes have replaced traditional corn brooms at every level of curling; it is rare now to see a curler using a corn broom on a regular basis.

Curling brushes may have fabric, hog hair, or horsehair heads. Modern curling brush handles are usually hollow tubes made of [[fiberglass|fibreglass]] or [[carbon fiber|carbon fibre]] instead of a solid length of wooden [[dowel]]. These hollow tube handles are lighter and stronger than wooden handles, allowing faster sweeping and more downward force to be applied to the broom head with reduced shaft flex.
[[File:Legal brushhead in curling.jpg|thumb|Following the ''broomgate controversy'', these mustard-yellow broom-heads are the only legal broom-heads certified by the [[World Curling Federation]] for competitive play.]] In 2014, new "directional fabric" brooms were introduced, which could influence the path of a curling stone better than the existing brooms. Concerns arose that these brooms would alter the fundamentals of the sport by reducing the level of skill required and giving players an unfair advantage; at least thirty-four elite teams signed a statement pledging not to use them. This was dubbed the ''[[Broomgate|broomgate controversy]]''.<ref>{{cite news |title=Top curling teams say they won't use high-tech brooms |url=http://www.cbc.ca/news/canada/manitoba/top-curling-teams-say-they-won-t-use-high-tech-brooms-1.3274903 |access-date=21 October 2015 |work=[[CBC News]] |date=16 October 2015 |url-status=live |archive-url=https://web.archive.org/web/20151022035711/http://www.cbc.ca/news/canada/manitoba/top-curling-teams-say-they-won-t-use-high-tech-brooms-1.3274903 |archive-date=22 October 2015}}</ref><ref name="icePad">{{cite web |last=Ouellette |first=Jennifer |title=Here's the Physics Behind the 'Broomgate' Controversy Rocking the Sport of Curling |url=https://gizmodo.com/heres-the-physics-behind-the-broomgate-controversy-rock-1781822352 |access-date=13 June 2016 |website=Gizmodo |date=12 June 2016 |url-status=live |archive-url=https://web.archive.org/web/20160612151325/http://gizmodo.com/heres-the-physics-behind-the-broomgate-controversy-rock-1781822352 |archive-date=12 June 2016}}</ref> The new brooms were temporarily banned by the [[World Curling Federation]] and [[Curling Canada]] for the 2015–2016 season.<ref name="MyUser_Ctvnews.ca_January_7_2016c">{{cite web |url=http://www.ctvnews.ca/sports/curling-canada-bans-broom-heads-with-directional-fabric-1.2677653 |title=Curling Canada bans broom heads with 'directional fabric' |newspaper=CTV News |date=27 November 2015 |access-date=7 January 2016 |url-status=live |archive-url=https://web.archive.org/web/20160101232900/http://www.ctvnews.ca/sports/curling-canada-bans-broom-heads-with-directional-fabric-1.2677653 |archive-date=1 January 2016}}</ref>  Since 2016, only one standardized brush head is approved by the World Curling Federation for competitive play.<ref name="Brush Head Moratorium">{{cite web |url=https://www.curling.ca/team-canada/hp-athletes/policies-guidelines/brush-head-moratorium |title=Brush Head Moratorium |publisher=[[Canadian Curling Association]] |access-date=8 July 2021 |archive-date=11 July 2021 |archive-url=https://web.archive.org/web/20210711115845/https://www.curling.ca/team-canada/hp-athletes/policies-guidelines/brush-head-moratorium/ |url-status=live }}</ref>

=== Shoes ===
{{more citations needed section|date=August 2014}}
[[File:curlingshoes.jpg|thumb|Curling shoes, showing a slider sole]]

Curling shoes are similar to ordinary athletic shoes except for special soles; the ''slider shoe'' (usually known as a "slider") is designed for the sliding foot and the "gripper shoe" (usually known as a ''gripper'') for the foot that kicks off from the hack.

The ''slider'' is designed to slide and typically has a [[PTFE|Teflon]] sole. It is worn by the thrower during delivery from the hack and by sweepers or the skip to glide down the ice when sweeping or otherwise traveling down the sheet quickly. Stainless steel and "red brick" sliders with lateral blocks of [[PVC]] on the sole are also available as alternatives to Teflon. Most shoes have a full-sole sliding surface, but some shoes have a sliding surface covering only the outline of the shoe and other enhancements with the full-sole slider. Some shoes have small disc sliders covering the front and heel portions or only the front portion of the foot, which allow more flexibility in the sliding foot for curlers playing with tuck deliveries.<ref>{{cite web |url=http://glennpaulley.ca/curling/2011/05/22/curling-shoes-choosing-a-slider/ |title=Curling Shoes:Choosing a Slider |url-status=dead |archive-url=https://web.archive.org/web/20120418161202/http://glennpaulley.ca/curling/2011/05/22/curling-shoes-choosing-a-slider/ |archive-date=18 April 2012 |access-date=12 August 2011 }}</ref> When a player is not throwing, the player's slider shoe can be temporarily rendered non-slippery by using a slip-on gripper. Ordinary athletic shoes may be converted to sliders by using a step-on or slip-on Teflon slider or by applying [[Electrical tape|electrical]] or [[gaffer tape]] directly to the sole or over a piece of cardboard. This arrangement often suits casual or beginning players.

The ''gripper'' is worn by the thrower on the foot that kicks off from the hack during delivery and is designed to grip the ice. It may have a normal athletic shoe sole or a special layer of rubbery material applied to the sole of a thickness to match the sliding shoe. The toe of the hack foot shoe may also have a rubberised coating on the top surface or a flap that hangs over the toe to reduce wear on the top of the shoe as it drags on the ice behind the thrower.

=== Other equipment ===
Other types of equipment include:

* Curling pants, made to be stretchy to accommodate the curling delivery.
* A stopwatch to time the stones over a fixed distance to calculate their speed. Stopwatches can be attached either to clothing or the broom.
* Curling gloves and mittens, to keep the hands warm and improve grip on the broom.{{clear}}