Sweeping

Sweeping Quick Reference

Sweeping Simplified

This section offers a simplified version of sweeping instruction. If you are a new curler, read this section and view the video above before your Learn to Curl Session. All of these things will be covered in the session.

A universal truth - Sweeping briefly warms the ice surface, reducing friction. It makes rocks go farther and straighter. 

When it is your turn to sweep:

In addition, with practice:

The remainder of this section will cover the details of sweeping.

The Purpose of Sweeping 

Sweeping effects the rock-ice interface, where the running surface meets the ice. The running surface of the rock, which is about five inches in diameter is the only thing in contact with the ice. Sweeping the ice in front of the running surface as the rock travels, changes the ice surface by warming it slightly, changing the coefficient of friction. A good sweeper may increase the temperature by only a degree or two, which is enough to effect the rock. The fabric on some brooms may scratch the ice creating small grooves.

Sweeping does several things:

Using Two Sweepers

In the traditional four-on-four format, one person skips, one person throws and the other two sweep.  For the best sweeping effectiveness, both sweepers must work together.  This is another good example of team play.  The sweeper nearest the rock is warming the surface the most since they are only a few inched away from the running surface.  The second sweeper is "preheating" the entire area.  For this preheating to benefit the inside sweeper, the second sweeper must be within two feet of the rock.  Beyond the two foot area, the ice will drop back down to the original temperature.

How Much Effect Does Sweeping Have?

Contrary to popular belief, sweeping only has a minimal effect on the moving rock.  To put it in perspective, league quality sweepers (see the page on Sweeping Performance), with an average head pressure of 60 lbs., can increase distance by 2-3 feet.  Over the length of the shot, which is bout 100 feet, this only represents a 2-3%, which would be considered minimal.  Even top-level sweepers only have about 10% effectiveness.

Sweeping Rule Summary
The World Curling Federation controls the rules of curling for most countries and all world championships. Rock manipulation through sweeping has been a difficult thing control and the rules have changed many times over the years. Today, there are no restrictions regarding the brush stroke. Sweeping in any direction and over any area is legal. However, the brush stroke must finish "away" from the running path as not to leave debris that may cause rock manipulation. Intentionally leaving debris (dumping) is a violation of the rules and may be punished by removing the rock in question.

Keeping the Ice and Rocks Clean
With today's ice maintenance and cleaning procedures, debris is kept to minimum and the only concerns are very small types of debris. Even something as small as a hair, fabric from clothing and dirt from shoes can cause the rock to change course.

"Pick" is the term curlers use when the rock is affected by debris. The term came from rocks "picking up" debris. Rocks are susceptible to picks, even on freshly scraped and swept ice. There's also an increased chance of picks as the game continues due to the pebble slowly eroding. As the ice gets "flat" there is more contact between the ice and the running surface. The condition of the rock's running surface also contributes to picking. Uneven or pitted surfaces are of particular concern.

There are a few things you can use to minimize picks since no team can ever afford a picked rock. Try the following.

The "cleaning" stroke must have enough pressure to avoid debris "rolling" under the broom head but not enough to melt or scratch the ice. Teams must agree on how much pressure they will use. Pressure less than five lbs. could allow the roll-under.

Countless games have been determined by picks. Be aware, clean and enjoy good shots.

"Cleaning" the ice as the rock travels
Bullet #2 above refers to the active cleaning of the ice in front of a moving rock. Many "pick-conscious" teams do this. One sweeper lightly sweeps the area to remove debris. The amount of pressure necessary for this is tricky. A very light sweep (one or two pounds of pressure) may be counter-productive. In this case, debris may "roll under" the broom head. By applying more pressure (10 pounds) will be much more effective in cleaning the area, however 10 pounds of pressure may actually make the rock travel farther and straighter. Your team should discuss this and decide how to proceed.

The most effective cleaning method is to use the 10 pounds of pressure and adjust the weights accordingly. If the ice is running 14.5, adjust to weight to something like 14.6 to compensate.

Of course, there are times when is "pick" is welcomed. A rock thrown clearly too heavy may need some help stopping. As long as it is not intentionally dumping, picks can be welcome.  Many skips come up with a term to allow this.

Directional Sweeping
See the section below, "Directional Sweeping".

Mechanics of Sweeping

Let's talk about what makes a good sweeper. The best sweepers today are effective and efficient. Sweeping effectiveness has been the focus of much debate over the last thirty years or so. While many people argue that the most effective sweeping comes from rapid movement of the brush, others argue that effective sweeping is caused by increased pressure of the brush on the ice. CurlTech believes that a strong balance of both will achieve optimum results. Rapid movement  (4-5 strokes per second) with as much pressure as possible is what great sweepers strive for. 

Sweeping efficiency refers to a sweeper's ability to be the most effective while using the least amount of energy. The sweeping style discussed in this section is the preferred method of most top teams. CurlTech teaches a sweeping style with the following main components:

The Sweeping Stroke 

Stance
To start sweeping properly, take a standing position that is 45 degrees to the rock's path, trying to face the rock and the skip at the same time. With the brush head on the ice, place the inside hand (the hand closest to the rock) on the brush handle half-way down using downward pressure. This is the bottom-hand, and it will be supporting much of your body weight during the sweeping stroke. The outside hand (top hand) should be placed underneath the handle (an underhand grip) about one foot from the top. The end of the handle will be tucked under the arm.


There are two types of brush motions:

The shoulder-driven motion is more powerful since the lower arm can be used to hold your body weight over the broom. Right-handed players will feel more comfortable on the right side with the left arm down. The lower hand motion is driven by the lower hand pushing the head back and forth. This is not as effective since the body weight can not be supported as well. To be as versatile as possible, learn the shoulder-drive from both sides.

Open vs. Closed Stance
There are two types of sweeping stances, open and closed. An open stance is one where the down-hand is on the inside, near the rock. A right-side sweeper would have the left arm down. A closed stance on the same side would have the right arm down. Since most people have a stronger side, this position allows some people to switch sides without switching strokes. The advantage of an outside arm down position (closed) is a more perpendicular sweeping stroke. This helps two sweepers stay close. The disadvantage is the body position. The head travels in a more backward style. This results in poorer visual communication with the skip and poorer weight judgment (the field of play is moving sideways across the body instead of into it).  The open stance will keep your head in an upright position and will help judge "convergence".

Head pressure and head speed can be produced equally with both stances so as an individual with no other sweeping responsibilities, it makes no difference which stance you choose. However, sweeping with an open stance will produce a stronger stroke due to the pushing action of the shoulder. The broom head is pushed away from the body by the shoulder. A closed stance will generate the same pressure but not the same power stroke. See the section on team sweeping for other important considerations when deciding which stance is right for you.

Benefits of the Open 45 Degree Stance

Although the head pressures are similar, the open stance has some clear advantages.

High vs. Low
The proper lower-hand grip is about 18 inches from the broom head. A grip any lower will REDUCE the amount of potential head pressure. For a short period of time (a few years) it was thought that the lower the hand, the better the head pressure. This turned out to be false. A higher grip allows you to move more of your body weight over the head. This means a more upright stance will allow most of your body to stay over to the brush head. The lower the grip and stance forces the body to stretch out horizontally, taking body weight away from the head.

Brush Motion
The most effective sweeping motion is approximately 45 degrees to the rock's path and covers an area just wider than the running surface (remember it's only five inches). A motion greater than this is waste of energy (not efficient). The stroke should be away from your body, and then back toward your body. Keep your top arm tight to your body. By staying tight, with practice, you will begin to put more and more pressure on the head as you begin to move your weight over the top of the brush.

The CurlTech "Power Stroke"
Experience and testing shows that the push (away) stroke is much more powerful that pull stroke. In fact, the area of highest pressure is only about 2-3 inches wide at the beginning of the push stroke.  After the initial 2-3 inch push (Power Stroke), pressure immediately breeds off.  The longer the stroke, the more bleed-off.  The goal is to get back to the Power Stroke as quickly as possible.

With experience, you will gradually place more of your body's weight over the head of the broom. The power of the sweeping stroke comes from the top shoulder (shoulder driven). The shoulder "drives" the brush head out and your core strength pulls it back. Because of this, most right-handed curlers (strong right side) will feel more comfortable sweeping on the right side of the rock.

Your dominant arm may dictate your preferred side to sweep. A good, shoulder-driven sweeping stroke will feel more comfortable with the non-dominant arm down. Since the power in the stroke comes from shoulder and the body weight is held by the lower arm, the dominant side will feel more natural. In some cases, the other side will feel more comfortable. This is usually because the dominant arm (lower arm) is doing the sweeping. This is not correct since the head pressure will decrease without the driving shoulder and the body weight on the broom. This is called a "jiggle arm" and is not very effective. This why some sweepers feel more comfortable with the strong side down.

For best results, place the strongest sweeper about 4 to 5 inches in front of the traveling rock. This is called "taking the rock". With the brush head at 45 degrees to the path, move the head back and forth with a clear and visible motion. Most adjustable brush heads are at least five inches long, so the running surface is automatically covered by simply placing the broom head in front of the rock. Any clear and visible movement at this point is acceptable. The second sweeper should be as close as possible to the inside sweeper without risking contact with the brushes. As a beginner, you may want to stay well clear of the rock to avoid hitting it with the brush. The most effective team sweeping is with the sweepers on opposite sides because the brushes can easily stay close together. Eighty percent of team sweeping effectiveness on draws comes from the inside sweeper, the outside sweeper representing the other twenty percent. However, the only way the inside sweeper can achieve this eighty percent is with the second sweeper present. The lead sweeper (farthest away) prepares the ice for the inside sweeper. They work together to create great sweeping. Sweeping with only one person will reduce the effectiveness by forty percent.

Note: Adding a third sweeper accomplishes almost nothing. As a skip or a thrower, avoid "jumping in" to help. This is a waste of time and only increases the chances of you or a teammate burning a rock.

Directional sweeping from melting/polishing, is achieved by Zonal Sweeping discussed in the Directional Sweeping section.

The Foot Motion 

Two methods of footwork:

Option #1 is much more stable and focuses the body weight on the feet.  Only limited head pressure can be achieved with this method but it is MUCH more stable.

Option #2 will provide more head pressure and is discussed below.

Proper sweeping must be done without a slider. Sweeping effectiveness requires a solid platform to sweep from. The proper sweeping motion, when moving with the rock, looks like a skating motion. Walking fast or jogging next to the rock is not very effective or efficient since most of your body weight is over your feet and not the brush head. As you move with the rock, your inside foot should be skating forward. Your outside foot should also be skating forward, but it will lead the body. The outside foot will extend much farther than the inside. The inside foot should also never cross the outside foot during the motion. The most pressure is created when the body weight is over the top of the brush. This can only happen using the tripod method with two feet and a brush head. In the beginning, you will have to support your weight on your feet. When you become more comfortable, begin to shift more and more weight onto the brush head.

To have the greatest degree of flexibility with your teammates, learn to sweep effectively on both sides of the rock in an open stance. This will allow you to sweep with anyone at any time.

Sweeping with a Slider
You may have seen good curlers sweep without covering their sliders. This is a personal preference. At club level head pressures, It does not benefit you as a sweeper, although some say weight judgement is better while you're sliding. It does take less energy to sweep this way which is why it's so popular. You cannot apply as much head pressure when sweeping with a slider. For this reason, we recommend you keep your gripper on when you sweep.  The top ten percent of elite sweepers apply so much pressure that the slider won't change things.  It is only when the body weight is positioned over the sliding foot that it matters.

Pro Note: At the highest head pressures, it doesn't matter what is on the sweepers feet.  Most of their body weight is already on the brush head.

Of course, there are different standards for Mixed Doubles curling format. If the thrower will also sweep, they have no time to put a gripper on.

Preparing to Sweep 

As the shooter prepares to throw the rock, the sweepers must take a position near the tee line and the side lines. This allows the shooter to view the skip. As the shooter begins to come out of the hack, the sweepers slowly meet the delivery at or near the hog line. One sweeper will always "take the rock" which means sweep closest to the rock. As a general rule, the person taking the rock will "clean" the surface in front of the rock to avoid the rock picking up small debris. Clean by slowly moving the brush head across the surface. The pressure should be light as not to create too much friction. This cleaning should be done in a position ready for sweeping if the skip calls.

Quick Tip:
When a right-handed player throws the rock, their broom is extended out to the left. This interferes with the left side sweeper at the beginning of the shot. If directional sweeping is not part of your team plan, have the right-side sweeper take the rock, since there is no extended delivery broom. This allows the sweeper to clean or sweep at a much earlier point.

When finished, move immediately to the sides and walk back in a non-distracting manner. It is not necessary to stop completely.

Sweeping Performance

Everyone agrees that more head pressure means more effective sweeping.  Your performance goal is to get as much head pressure as possible.  Brush head frequency is less important but still need to be in the 4-5 strokes per second area.

Since 2015 when the theory of sweep-scratching was introduced, advanced curlers experimented with different sweep styles. This is an ongoing effort. The new theory opened the door to lots of speculation, additional theories, many spirited discussions, and strong beliefs. CurlTech is continuously monitoring the sweeping issue and will stay as current as possible with new ideas.

The new sweep science of 2024 may change how we view sweeping.  See the Directional Sweeping Section.

Studies have shown that the most effective sweeping style is the one that adds the most pressure and repetition (sweeping over the same area). So how do you get the most pressure? A test using a simple bathroom scale will show that more pressure can be applied to the head of the broom if the body position is higher (lower hand on the broom 12-18 inches from the head). As the lower-hand moves closer to the head, less pressure will be applied because the lower position spreads the body weight horizontally. As your body bends over, more weight is distributed back to the feet. Higher hands spread the body weight vertically over the head.

The remainder of this section will cover some advance sweeping concepts and techniques that can be used by teams. The topics are:

Measuring Performance

Up until the year 2010, measuring your sweeping effectiveness was limited to rock results.  Stopwatches that measured split times helped to measure shot speed that could also help measure how far you could "carry" the rock.  Only visual references can measure straightening and "carving".

The SmartBroom

The SmartBroom, developed and distributed by SmartBroom, Inc., measures sweeping head pressure and frequency in pounds, and strokes per second, respectively (it does not measure the length of the sweeping stroke).  I thin, scale-like device inserted between the brush head and pad, will measure the pressure and frequency via Blue Tooth to the SmartBroom app.

CurlTech has hundreds of SmartBroom data points from the clinics we conduct.  Pressure numbers range from just a few pounds to an extraordinary 180 pounds.  At CurlTech clinics and certifications, we offer "baselining" of your sweeping performance using the SmartBroom.  Nearly all of our clinic participants get baselined since most curers want to "know their number".  It is a very effective measurement and training tool.

Performance Categories

There are three categories of sweeping performance - all measured by the percent of body weight put on the brush head during the Power Stroke.

Category Metrics Mechanics

Recreational Up to 25% of body weight. Most body weight on feet.

Athletic Between 25 and 75% of body weight. Bottom arm holds up body weight over brush head.

Elite Athletic Over 75% of body weight. Arms "drive" body up.

As an individual contributor to your team, your sweeping category must match your goals and commitment.  Be the best you can be with your body mass and strength.

Don't let body weight dictate your performance.  Notice in the elite athletic category that the mechanics change from holding up the body weight to "driving" the body up.  Similar to a bench press, if you exert more energy than the body weight, the resulting head pressure increases exponentially. We have hundreds of pressure data points on curlers in all three categories.  Body weight has less to do with performance than body strength and athleticism.  We've seen a 110 pound person create 80-90 pounds of pressure, a good example of the Elite Athletic category.  Of course body mass and strength is a limiting factor.  A 200 pound, strong, athletic person will be able create more pressure than the example above. 

Performance Metrics

The above categories measure you capacity and are good for classifying sweepers of all sizes.  However, the absolute sweeping pressure number determines true effectiveness.  Consider the following:

Non-Compliant Brush Heads (league heads)

Power Stroke Effectiveness Distance Straightening Carve/Push/Curl*

10-40 lbs. Minimal effectiveness less than 1 foot None - minimal None

40-70 lbs. Somewhat effective. 1-3 feet 1 inch None

70-110 Effective 3-6 feet 2 inches None

110-140 Highly effective 6-10 feet Over 2 inches Possible

Over 140 Best in class effectiveness. 10-12 feet Zero Curl Possible Yes

WCF Compliant Brush Heads (yellow heads)

Power Stroke Effectiveness   Distance Straightening Carve/Push/Curl*

10-40 lbs. Minimal effectiveness 1 foot None - minimal None

40-70 lbs. Somewhat effective. 2-3 feet Less than 1 inch None

70-110 Effective 3-5 feet 1 inch None

110-140 Highly effective 6-8 feet 2 inches None

Over 140 Best in class effectiveness. 8-12 feet. Zero Curl Possible Maybe

*From scratching.  Directional sweeping from melting is possible but requires a different brush stroke.

Performance Tips

Team Sweeping Systems
 Most of the discussion so far has been about why we sweep and how we sweep. Those of you who curl mostly in leagues as an individual contributor will benefit greatly from the basic mechanics. If you play on a team that plays together regularly, you have the opportunity to take sweeping to next level by applying some team sweeping techniques.

Team Control Factor (TCF)
Team sweeping comes in twos. The perfect draw shot is thrown two feet short and the draw broom is two inches more than needed. The perfect takeout broom is two inches less than needed.

Once the rock has been delivered, the sweepers are responsible for judging the weight. Is it moving too fast, too slow, or just right? t is not realistic to expect the skip to judge the weight from 120 feet away. After the rock has been thrown, the sweepers place the rock. By understanding the shot called, the sweepers can determine if the called spot is possible. If it is, the sweepers complete the shot. If the weight is heavy or light, the sweepers must communicate to the skip the new location. The skip then makes a line sweeping decision based on whether or not the rocks curl needs to be straightened-out.

Judging the weight of the rock is very difficult and takes lots of practice. You can increase your ability to judge rocks with a few sweeping techniques.

Team sweeping refers to teams striving for similar sweeping styles. This continuity will make all sweeping calls more consistent .For example, the most effective sweeping is two sweepers sweeping from opposite sides of the rock. This allows the brushes to be as close as possible to each other, limiting the amount of cool down that happens after the brush passes over the surface.

Who Takes the Rock?
If your team uses directional sweeping in any way, use what's called the "control" system . On each shot, the sweeper on the inside of the curl (right side on an in-turn) is the "Primary" sweeper. The primary takes the rock, starts in a ready position, and cleans the entire time. The other sweeper will take split times and communicate to the skip as necessary. The default sweeping on draws is to add distance and on take-outs to keep the rock straight. The inside sweeper always has a better directional stroke for straightness. The outside sweeper may or may not sweep at all. On draws, as the rock is crossing the hog line and is most susceptible to directional sweeping, the communicator will switch and act as the control sweeper to possibly finish the draw.

Determining who is the primary sweeper is based on the shot called. Good team sweepers never need to confirm this.

Weight Judgement and Communication

For the most part, sweepers judge weight and skips judge line. It is very important for both parties to understand each other. For example, a skip judges line based on how the rock was delivered and how they think the rocks will curl. Since rocks curl less with more weight, the skip must know any weight deviations as soon as possible.

Judging the weight of a rock and communicating properly takes time and practice. Weight judgement is best when your spatial and proprioception skills are good.

Spatial Skills
Spatial skills are the ones that sense your body position in relation to your surroundings allowing you to measure speed and convergence. The better your spatial skills, the more likely you will judge the linear movement of the rock properly. These skills are difficult to develop but practice will help.

Proprioception Skills
These skills are the ability to sense your body's position within its own space. Balancing in the delivery and sweeping over the broom head are both good examples (a perfectly balanced delivery is a better example).

With both skills, it is important that you put your body in a position that does not compromise the senses. Keep your head as upright as possible and face your target since the inner ear fluids will effect your perception if disturbed. An open sweeping stance will help keep your head in the proper position. The closed stance, although not incorrect, will put your head in a tilted position and moving slightly sideways. Since your weight judgement is mostly spatial (judging the rock from where you are to where you want it) an upright forward position is best.

Draw Weight and Rock Position Systems
Teams can use any weight and position system they desire. Many teams use a numbered system to communicate draw weight and rock position.

The Numbered, 1-11 System.

Another system is the "house position" system. In this system, sweepers call out the house position such as top twelve, back eight, etc. This may be easier for some teams.

The more intuitive House System:

This is a more intuitive system since no conversion is necessary in the language. It works well with shots played in the middle of the sheet. It does have a drawback, however. Shots played to the sides are difficult to place since a rock in the top four (6 on the 1-11 system) on the centerline will be in the twelve foot near the side-line.

Using the 1-11 system or the house system, try the following:

Before the rock is thrown, make sure the sweepers know the exact shot and weight called. If throwing a draw for example, the sweepers should communicate any weight differences to the skip as soon as you are sure that the weight is NOT as called. Commit to an area of the house such "top four" or "back twelve". This can be verbal or visual depending on the circumstances. As the rock travels down the ice, the sweepers must continuously report the weight differences to the skip. To simplify matters, only communicate weight if it is different than what the skip expects. Over-communicating such as screaming "the weight is good" is not necessary. Effective communication is not necessarily constant communication. In fact, a better use of sweepings is to have them communicate between each other and not the skip.

Sweepers should communicate these "exception" numbers to the skip as soon as possible. It is not necessary to communicate detailed weight positions at the release point. At the halfway point, the sweepers must commit to something. At the hog line the sweepers must be certain. The system will get very confusing if teams don't understand the "swept verses un-swept" numbers.

The CurlTech Weight Communication System
A better system that incorporates this numbering system is the "quiet system". Using this system, the sweepers communicate by exception.  Little or nothing is said if the weight is correct. This is difficult for most skips, particularly the ones that require constant updates. This system works on established teams with a high degree of trust.  Many people think that verbalizing nothing means saying nothing.  Just the opposite.  Using this system, verbalizing nothing says a lot.  This system has has three benefits:

This "by exception" system works well because it keeps the noise to a minimum especially in loud arenas and clubs. This system represents the highest level of team development since it requires trust and skill.  The system is based on the called shot.

Mechanics of the System throwing a draw.

Mechanics of the System throwing a takeout.

Example of the System
The skip calls a draw to the top four-foot (6) and the sweepers confirm with each other. If the sweepers can make the shot (6) they say nothing until they know (or think) it's not in the six position. If they can get it to the four-foot with sweeping, they still say nothing and sweep. If the weight is heavy, they immediately communicate the heavy weight resting position, such as 8 or 9. The skip can then decide if an alternate is necessary. If the weight is light, the sweepers communicate the swept weight such as 3 or 4.

It is always necessary to confirm the shot with the sweepers and thrower before the shot is thrown.

Directional Sweeping

By definition, Directional Sweeping is any sweeping motion, equipment or mechanism that effects the natural curl of the rock.  For many years, sweeping was known to make rocks go farther and straighter.  The straightening part could be called "directional" since it effects the curl.

In 2015, because of new information about why rocks curl, some elite curlers experimented with what is now called scratch-related "directional sweeping". Directional sweeping is used to keep rocks straight as well as to increase the curl. The idea of creating additional scratches on the ice (with your broom) will help the natural action of tracking through the scratches. In order to get rocks to curl more, the "high side" sweeper (on the opposite side of the curl direction) sweeps/scratches the path at angle up to 45 degrees in the direction of the intended curl. Depending on the type of broom, this creates additional track scratches. It's important to understand that the directional results from scratching will come from only one side. If two sweepers are scratching on opposite sides, they will counteract the results although two sweepers have always been used for weight sweeping.

Note: There are WCF rules regarding the type of brooms (pads and fabric) that can be used in events leading to world play. Check the WCF website for more information and check your country's governing body for more local rules.

To enhance the scratching, a new fabric type was introduced to broom technology. Instead of the standard weave that had been used for decades, a "bi-directional" weave was created. Immediately, curlers protested the design as being inconsistent with the principles of the sport. Apparently, the new fabric scratched the ice surface and allowed much more control of the curl. Similar to the corner sweeping principle, sweepers could target the area to scratch (one side to keep straight, the other to curl more) with greater, almost unnatural results.

It did not take long for the new fabric to be outlawed. The WCF, citing too much control over the rock and possible ice surface damage, instituted a moratorium on the use of this fabric.

The idea of directional scratch-sweeping evolved from the new fabric controversy. Sweepers argue that the brush stroke, which is more powerful on the forward stroke than the return stroke, could effectively reduce friction on the inside edge. This is slightly different than the old corner sweeping because it focuses on the direction of the outward stroke instead of the result of the pressure. Since there is no way to change the pressure on a swivel head broom (as opposed to the fixed head), the direction of the stroke causes scratches in the ice that the rock tracks on.

In addition, sweepers argue that a second sweeper on the opposite side would "counter" the work of the inside sweeper.  As a result, you may see only one sweeper working the inside edge of a rock that needs to be straightened.

Directional-straight sweeping can be accomplished at all levels, even at lower head pressures (40 lbs. and higher).

Directional-curl sweeping can only be accomplished at the highest head pressures (over 150 lbs.).

Keep in mind that most league curlers are in the 40-60 lb. pressure range.


There are two different mechanisms for directional sweeping:

Scratching/Grooving Mechanics

Warming/Polishing Mechanics

BTW - Both warming methods can be done from either side of the rock since there is no scratching involved.

2024 Sweeping Science Study

Multiple studies have shown that the WCF compliant brush head does not scratch enough to be effective, particularly at the recreational or even athletic sweeper categories. Do not expect any scratch-based directional results with this head. Straightening can occur but not as a result of scratching.

The dominant mechanism here is differential warming and NOT scratching.

A Note of Caution.

Players at all levels are using the scratching stroke in an attempt to curl rocks.  Unless your sweepers are the top of the Elite Athletic category (175 lbs. of pressure) it is not likely that you can curl a rock by scratching.  In, fact the scratching stroke is the opposite of the warming stroke and you are likely to achieve the opposite result.

Zonal Sweeping

Pro Reminder: The second sweeper (farther from the rock) will pre-heat the ice in ALL cases).

Zonal sweeping is a form of directional sweeping without the scratches. In support of the frictional warming theory, CurlTech developed an updated system of "Sweeping Zones".  Using the Power Stroke (only 2-3 inches), sweepers, mainly the inside sweeper, focus on applying the peak pressure to three different zones. 

Zone Outcome

Inside Straightening

Middle Distance or carry

Outside Curl (in theory)

Zonal Sweeping warms/polishes certain areas.  It is not a scratching theory.

The inside, middle, and outside zones are in front of the running edge.  Zonal sweeping attacks three areas of the running surface instead of sweeping across the entire surface. This is to maximize control over the rock's curl profile. For example, by sweeping the inside edge of a takeout (the slow side of the rotation), friction is reduced on the slow side only, reducing the "pivot action" discussed earlier in this section. Because of this, the rock runs straighter. Sweeping the outside edge could make it curl more but seems to be much less effective unless there is extreme head pressure. Zonal sweeping results in more manipulative sweeping. This could result in less predictable shots on less experienced teams. We suggest you leave zonal sweeping for later in your team's development. Our staff members use zonal sweeping on their competitive teams with fabulous results. Even though zonal sweeping may be more effective, most recreational teams prefer to concentrate on good overall sweeping skills in front of the rock.

The "Illusory Correlation"

This term describes a positive correlation between what happened and how it happened.  For example.  You call for your sweepers to "curl" the rock.  You see the rock curl therefore attribute the curl to the brush action you called for.  It is more than likely that you are seeing the natural curl of the rock caused by the rock-ice interface and not from your brushing.  It is more likely that you helped miss the shot instead of make it.

Warm/Scratch Hybrid Combination

If you really think you can scratch the ice with your broom, the combination method may help.  Sweeping the outside zone will help melt and in theory enhance curl.  To enhance curl with this method:

This method warms the outside zone (good) AND scratches in the direction of the curl (if you can scratch).  The current scratching method starts in the middle zone and finishes away.  This covers the wrong zone for curl. 

Consider More Physics

Sir Isaac Newton most certainly was a curler.  He suggested that things in motion have tendency to stay in motion unless acted upon by an external force.  After watching his team throw take-outs, he noticed that the 42 lb. rock had a tendency to stay straight unless the rotation was causing an external force of differential frictional warming.  Sweeping to keep a rock straight made a lot of sense because it took very little energy to keep the rock moving the way it naturally wanted to (straight).

Getting the rock to curl was different story.  He noticed that it took much more energy (many times that of straightening) to move the rock off it's natural path.  The harder the rock was thrown, the more energy it took.  This makes it very unlikely that the action of a broom can take the rock off course.

 Systems & Equipment

"Finishing" the Draw 

Most curlers associate sweeping with rocks traveling farther and straighter. This is true for most shots. There is a case though when sweeping will cause a rock to appear to curl more. As a draw is coming to rest, many newer curlers continue to sweep the rock in an attempt to keep it straight. Sweeping will keep the rock moving, which means it continues on its path. Imagine the arc of a rock that is curling. It begins straight then starts to curl (see The Curl Profile).If the rock could move forever, it would eventually leave the sheet of ice across the sideline. Sweeping rocks after the curl begins does two things:

Finishing the rock refers to keeping it moving on its arc. This pulls the rock even deeper behind a guard because the rock is still moving on its curl path. This is important to know since many come-around shots can be "finished", meaning the rocks can be swept under the guard. The mistake many new skips and vices make is to stop sweeping. This only makes the rock stop short and not continue to curl under. On the other hand, if a rock is curling too much at the end, stop sweeping. Additional sweeping here will only continue the rock's path. Directional sweeping can help here. Not only will it keep the rock moving, but it may also help the rock curl more. Directional sweeping can offer something never seen before when it comes to finishing the draw. Directional sweeping on the inside of a finishing draw may keep it from curling. Be careful and test this theory yourself.

Sweeping Systems 

A sweeping system is an interrelated group of sweeping activities. Teams should design their own system by compiling known and proven components. In any sweeping system, you will have the following components:

Sweeping Equipment 

There are only a few types of sweeping devices being used today, all using synthetic fabric. These synthetic brooms have a fabric, such as Cordura, stretched over a padded surface. Although introduced many years ago, these synthetic brooms became popular in the mid 1990's and are the standard sweeping device today. They are very effective and keep the ice clean. Some people argue that the synthetic brooms are so effective in polishing the ice that they erode the valuable pebble that the rocks ride on. This creates an undesirable "flat" surface with more area of contact on the running surface.

Carbon fiber handles were introduced around the year 2000.They are much lighter than the standard fiberglass handles. They do not offer much in additional sweeping performance other than perhaps some increased head speed due to the lighter weight. These handles are much more expensive. If money is not an issue, choose the carbon fiber.

CurlTech Choice for individual (league type) sweeping:

Pro Note: There is only one fabric approved for all events leading to world play. The WCF has approved the 420 denier Cordura nylon as the only fabric. 

If your league or event does not require a WCF compliant broom - DON'T USE ONE.  They are much less effective, particularly at the lower head pressures.  They are however, much easier to use since they create less fabric pressure.

A note about broom regulations. The WCF has broom pad and fabric regulations for any games played that lead to world play. Only one fabric type (smoother, less-scratching) is allowed, and most broom manufacturers have a championship approved fabric pad. Check your local league rules as some more competitive leagues follow the WCF guidelines. Most club leagues do not use the use the WCF rule. In some cases, more competitive leagues have adopted it.

Equipment Type 

The best team brooms are the ones that create the most friction with the least effort and allow the two sweepers to sweep in close proximity. Lighter, carbon fiber handles dramatically reduce the weight of any broom reducing fatigue, particularly over longer competitions. The carbon fiber handle brooms are slightly harder to control due to the lack of weight. Head "float", meaning the head of the broom drifts off the line, may result during the transition to these brooms. As the head grabs the ice, the friction pulls the head toward the rock causing an oval pattern to the sweeping stroke. Many teams, however, will agree that the advantages outweigh the disadvantages of these brooms. For team sweeping, where the players are in fixed positions for each shot, swivel-head brooms provide the best coverage.

If using fixed angles, it will be necessary to switch brooms for different players. A team switching system is simple if the players are in proper position after each shot. A team can own four broom types for efficiency. A straight broom for sliding and skipping and angles for sweeping.

CurlTech Choice for team sweeping equipment:

Sweeping Style
The same sweeping style described earlier in this section should be used by the advanced players. The sweeping stroke must be short, vigorous and with as much pressure as possible.

Positioning
Positioning refers to where and when each team members place themselves during the game. Competitive games are timed, and effective positioning helps play quickly without rushing. Select a position for each player that can be replicated each end.

The "Ready Position"
Those of you that coach or play baseball or softball understand the "ready position" concept. This refers to the position of the players as the ball is put into play. In curling, the sweepers take a ready position just before they need to sweep (or are called on to sweep).The person taking the rock (closest to the rock), must be in the ready position AND cleaning the path at all times. Cleaning the path helps prevent "picks" and allows the sweeper to sweep immediately when the skip calls. The outside sweeper (not on the rock) needs a ready position that is upright and facing the skip. This sweeper communicates weight information to the skip.

Clean in front of the rock at all times unless you want a pick. Create a skip's signal to stop cleaning. There are times when a pick may help.