This section will cover a wide variety of sweeping topics. Specifically, the areas covered are:
This section contains lots of material. You will benefit from reading all the content. If are new to the sport, read the following.
This section offers a simplified version of sweeping instruction. If you are a new curler, read this section before your Learn to Curl Session. All of these things will be covered in the session.
Sweeping makes the rock 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.
Sweeping affects the rock-ice interface. The running surface of the rock, which is about five inches in diameter (Figure 1) is 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 affecting the distance. The friction of the broom also creates small grooves in the ice, affecting direction.
In the early days of curling, when games were played outdoors on the lochs, snow and other debris was cleared from the path of the moving rocks. Bunches of sticks were used as debris clearing devices. However, as the sport evolved, it became clear that, in addition to clearing debris, vigorous sweeping affected the moving rocks.
Sweeping does several things:
All sweeping decreases the rock's rate of deceleration.
Sweeping Rule Summary
Keeping the Ice Clean - the "Pick"
"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. If melting and scratching are an issue, a good team will always favor the short end of the weight window to allow cleaning.
Countless games have been determined by picks. Be aware, clean and enjoy good shots.
"Cleaning" the ice as the rock travels
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 needed. A rock thrown clearly too heavy may need that help. Many skips come up with a term to allow this.
Note: There are new 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.
Most researchers will agree that we cannot completely discount either theory. Test for yourself.
The weight window was briefly mentioned in the Delivery Section. The amount of force necessary to propel a rock forward is known as "weight". Good sweepers can add an additional 4 - 8 feet to a rock's distance. This is important to know because, as you are throwing the rock, your throwing weight needs only to fall inside this 4 - 8 foot "weight window". This provides a fairly comfortable margin of error for a thrower with good sweepers.
Example: A rock thrown 8 feet short of the house without sweeping can easily be swept into the house by good sweepers. As a thrower, your responsibility was to hit the "window" and not the actual finished shot. This is what makes sweeping such a critical part of the game.
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:
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.
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 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:
Two Types of Brush Motions
The should 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 id driven by the lower hand pushing the head back and forth. This is not as effective since the body weight can not be support as well by a moving hand. To be as versatile as possible, learn the shoulder-drive from both sides.
High vs. Low
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 in a closed stance.
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 perpendicular 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.
In the Delivery Section, the use of a slider was discussed. Proper sweeping must be done without a slider. If you throw with a slider, remove it for sweeping. If your slider is built into your shoe, cover it with a gripper. 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. 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. This will allow you to sweep with anyone at any time.
View the following video to see strong, effective, and efficient sweeping:
View the short video of proper sweeping mechanics. She uses good head pressure and good head movement.
Sweeping with a Slider
Of course, there are different standards for Mixed Doubles curling. If the thrower will also sweep, they have no time to put a gripper on.
Open vs. Closed Stance
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.
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.
When finished, move immediately to the sides and walk back in a non-distracting manner. It is not necessary to stop completely.
Since 2015 when the theory of sweep-scratching was introduced, advanced curlers have been experimenting 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 monitoring the sweeping issue and will stay as current as possible with new ideas.
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 move 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:
Rule #2 Team Control Factor (TCF)
Once the rock has been delivered, the sweepers are responsible for judging the weight. Is it moving too fast, too slow, or just right? It 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.
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 he or she thinks 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.
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 change your perception if disturbed. An open stance will help keep your head in a good 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. Remember, we are judging where it will stop and not how fast it is going.
Draw Weight and Rock Position Systems
Another system is 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.
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:
Sweepers should communicate these 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. Keep in mind, these are swept weights. The system will get very confusing if teams don't understand the "swept verses unswept" numbers.
The Perfect Weight Communication System
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.
Example of the Perfect System
It is always necessary to confirm the shot with the sweepers and thrower before the shot is thrown.
When learning this system, teams can start by using a less complex numbering system. The following can be used when just starting out.
In support of the frictional melting theory of why rocks curl, a new sweeping concept became popular in the 1990's called corner sweeping. This refers to sweeping across one side of the running surface instead of sweeping across the entire running surface. This was done to gain even greater control over the rocks curl. For example, by sweeping the inside edge of a takeout (the slow side), 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 of a draw could make it curl more but seems to be much less effective. Corner sweeping results in more manipulative sweeping. This could result in less predictable shots. CurlTech suggests you leave corner sweeping for emergencies only. Our staff members have seen corner sweeping in action and work very well. We've also seen disastrous results from corner sweeping every shot. If you really need to get around that guard, use it. Even though corner sweeping may be more effective, most good teams prefer to concentrate on good overall sweeping skills.
Corner sweeping does not appear to help rocks curl. Use it as a straightening tool.
Fixed Head Differential Pressure
Forward Stroke Corner Sweeping
Note:To straighten a rock, corner sweeping and directional sweeping use roughly the same stroke. So far, no studies have been done on which mechanism is dominant.
In 2015, 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 sweeping, the millennial version of corner 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 will see only one sweeper working the inside edge of a rock that needs to be straightened.
Mechanics of Directional Sweeping
In the Delivery Section, rotating the rock at release is discussed in depth. Many curlers at all levels target 3-4 rotations. In the "Why Rocks Curl" Section, the natural scratching of the running surface over the ice is explained. It is suggested that the ice is scratched by the leading edge of the running surface as it decelerates. This creates a scratch 90 degrees to the path of the rock. Since the rock is also moving forward, the natural scratch will get shallower as the rock travels faster (see the hart below). To summarize, the scratches created by the rock itself are dependent on how hard the rock is thrown and how fast it is rotating. Because the variability of the natural scratches, the speed and rotation change the angles needed for directional sweeping. For carving, the broom scratch angle should be just outside the natural scratch angle (45-degree natural scratches would require a broom scratch angle of 50 degrees). This not only compliments the natural scratch action, but it also helps the rock curl beyond its natural (non-swept) ability.
Consider the following chart for directional sweeping. Not for distance.
To complicate matters further, the rock will decelerate in speed faster than it will in rotation. This means the sweeping scratch angle will sharpen as the rock approaches the house.
*Rotating the same speed as the draw, roughly ten RPM's.
It's important for teams to agree on a rotation standard for the sweeping angles to match each player. A team member who throws 2 draw rotations will need a shallow angle (20) while the team member throwing 5 rotations will need a deeper angle (70).
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.
The sweepers are responsible for split-timing shots. Split timing (short times) is an excellent sweeping tool to help manage weight judgement and distance.
See a full write up on timing rocks in the "Timing Rocks" section.
As mentioned earlier in this section, sweeping can dramatically affect any given shot. Whether it's a takeout thrown narrow or a draw that needs help, effective sweeping is essential.
Like many systems, sweeping effectiveness is measurable. Brush head pressure and head speed are the two quantifiably measured components. Head speed is measured by the number of brush strokes per second. Out and back equals one stroke. Head pressure is measured by pressure sensors in the head of a special test broom. Since curlers are different sizes, the standard is measured in percent of body weight applied to the head. Coverage is measured by sustained coverage of the running surface, approximately five inches.
Below are the CurlTech sweeping standards:
sps = strokes per second, one stroke is out and back
Of course, these standards must be maintained for the entire sweeping session, sometimes the entire length of the shot. Do not expect to achieve the high-performance standard without being in top physical shape. Strength, particularly in the arms, shoulders and core is required to maintain the high-performance standard. The shoulder drives the brush out and the core pulls it back.
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:
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:
The "Ready Position"
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.
Who Takes the Rock?
Determining who is the control sweeper is based on the shot called. Good team sweepers never need to confirm this.
Unless your team uses directional sweeping, the "throwing arm" side sweeper should always take the rock. 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. Since there is no extending delivery broom, the right-side sweeper can clean or sweep at a much earlier point.
Sweeping Quick Reference