Olympic ski racers use chemistry to enhance their performance | Science News for Students

Olympic ski racers use chemistry to enhance their performance

Waxes allow athletes to control how their skis glide under some conditions and grip in others
Feb 12, 2018 — 6:45 am EST
waxing skis
Andrew Morehouse waxes skis on site for the U.S. Olympic Nordic Ski Team. The recipe he uses will depend on snow conditions. Choosing the right wax may make all the difference in whether top athletes can go for the gold.
US Ski Team

When the world’s top skiers face off this week at the Winter Olympics, they will be relying on years of training, mental preparation — and a good deal of chemistry. The chemistry of ski wax. The fastest skiers usually have the fastest skis. And speedy skis need their bottoms waxed with the right stuff.

All ski wax is not the same. The recipe an athlete uses must be tailored to match the feats they’ll attempt and the snow they’ll encounter. A wetter snow, for instance, will require a different wax than  dry fluff. And downhill racers get a different recipe than cross-country skiers.

Chemicals in the wax help skis glide downhill. The wax does this by repelling water that forms as a ski slides across the snow. Cross-country skiers, in contrast, must go both uphill and downhill. Their ski wax, therefore, must help the athlete also grip the snow while climbing short hills during a race.

One type of wax makes skis slippery. Another makes it grip. A racer who uses the wrong formula risks lagging behind. This also can happen if the snow’s properties change during a race. Maybe it gets colder. Or starts snowing. It may even rain. Such weather changes can alter the surface of the snow in ways that can make it harder on racers.

Kikkan Randall skiing
Kikkan Randall tests her ski wax before a cross country race. She and her coaches must choose the best wax recipe before racing at the Olympics in PyeongChang, South Korea.
US Ski Team

That’s what happened to Kikkan Randall. She is a cross-country ski racer from Anchorage, Alaska. Beginning February 10, she’ll be competing in PyeongChang, South Korea, as part of the 2018 U.S. Winter Olympics team.

Randall remembers her skis picking up new-fallen snow in Finland earlier this season. They were like chunks of mud on a race.

“I had 3 inches [8 centimeters] of snow on the bottom of my skis and had to scrape it off and keep going,” she notes. “It was clear that I had the ability to have a better race. But my skis were making it impossible. I would have been better off with no wax.”

Randall attributes some wins that brought her to the Olympics to the waxes she used. It allowed her to glide faster than other racers on the downhill part of the course. The recipe she and others use is critical. Racers get only one chance to wax their skis before a race begins.

Long before a race, various waxes will be tested. Then, technicians and racers pick a mix that they think will best match the snow on race day. They rub and melt layers of the chemicals onto the bottom of each ski. Then they scrape and polish each layer to make it super-smooth. Sometimes they add a sticky wax called “klister” — or kick wax — to the part of the ski below the boot. This helps racers grip if and when they need to climb.

Choices, choices

Like gasoline and natural gas, wax contains one or more hydrocarbons. As their name suggests, these molecules are made from a chain of hydrogen and carbon atoms. The first layer of wax applied to the bottom of a ski is similar to the paraffin wax used in candles. It forms a bond with the bottom of the ski to keep out dirt and water.

Randall skis
Kikkan Randall brings several dozen skis to each race. Each one has a different set of qualities and requires different wax combinations.
Kikkan Randall

The next layer contains fluorocarbons. These are molecules made from a mix of fluorine, hydrogen and carbon. These wax ingredients are designed for speed. They cut friction between the ski and the surface of the snow. (These chemicals are related to additives that manufacturers sometimes use to make rain gear repel water.)

Fluorocarbon waxes are softer than some other types. They may be used as fluids or as powders. For a two-minute downhill race, skiers want the slipperiest surface possible. They will need a different formula for a two-hour-long, cross-country event. Indeed, cross-country racers may apply six or more layers of wax to give a competitor control in moving up and down across a course.

Some fluorocarbon ski waxes also have extra hydrocarbons, such as acetone (ASS-eh-toan), benzene or toluene (TAAL-yu-een). These chemicals can be harmful if a person touches or inhales them a lot or over long periods. Yet they must be used repeatedly. After all, most of these chemicals will rub off a ski by the end of a race.

The chemistry of wax

Jeffrey Bates studies how ski waxes work. He is a materials scientist at University of Utah in Salt Lake City. He has invented a ski wax that can stick onto skis for the whole winter, not just for one race.

To do this, Bates pored over the bottom of plastic skis using a scanning electron microscope. It can display the surface of materials to a resolution of 1 nanometer (a billionth of a meter). For comparison, a human hair is 75,000 nanometers wide.

Under high magnification, the molecules on the bottom of the ski “looked like balls of spaghetti,” Bates says. Those spaghetti-like strands are polymers. Bates’ new liquid wax fills in the tiny nooks and crannies between the polymer strands. When exposed to sunlight, this coating chemically bonds to the ski. And that attachment is so strong it can last for months.

“We are not making this for racers,” Bates says. “We are making this for the regular person who goes to the slopes several times a year and doesn’t want to be bothered with waxing.” Why wouldn’t Olympians want it too? Its formula is set. It can’t be tweaked based on the particular conditions a competitor may need when going for the gold.

At the Olympics in South Korea, many teams will tweak their waxes’ chemistry in their bid to win a medal in ski racing. Each team will mix up its own secret recipe of waxes before the race starts.

“You try to do everything behind closed doors,” explains Andrew Morehouse. He’s a wax technician for the U.S. Olympic Nordic Ski Team. “I don’t know if there are spies, but it’s a natural thing to want to know what the other teams are waxing. Everyone keeps to themselves.”

For Randall and the other skiers, they hope that good chemistry will speed their path to the finish line.

Power Words

(more about Power Words)

acetone     A chemical produced by the body that is detectable in people’s breath. It’s also an extremely flammable liquid solvent used, for example, in nail polish remover.

atom     The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.

benzene     A ring-shaped hydrocarbon molecule made from six carbon and six hydrogen atoms. It’s liquid at room temperature and easily evaporates into the air. It’s widely used in industry and a natural constituent of petroleum, gasoline and cigarette smoke. It is highly toxic if breathed in large amounts and may cause cancer after prolonged, lower dose exposure.

bond     (in chemistry) A semi-permanent attachment between atoms — or groups of atoms — in a molecule. It’s formed by an attractive force between the participating atoms. Once bonded, the atoms will work as a unit. To separate the component atoms, energy must be supplied to the molecule as heat or some other type of radiation.

carbon     The chemical element having the atomic number 6. It is the physical basis of all life on Earth. Carbon exists freely as graphite and diamond. It is an important part of coal, limestone and petroleum, and is capable of self-bonding, chemically, to form an enormous number of chemically, biologically and commercially important molecules.

chemical     A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

chemistry     The field of science that deals with the composition, structure and properties of substances and how they interact. Scientists use this knowledge to study unfamiliar substances, to reproduce large quantities of useful substances or to design and create new and useful substances. (about compounds) Chemistry also is used as a term to refer to the recipe of a compound, the way it’s produced or some of its properties. People who work in this field are known as chemists.

electron microscope     A microscope with high resolution and magnification that uses electrons rather than light to image an object.

fluorine     An element first discovered in 1886 by Henri Moissan. It takes its name from the Latin word meaning “to flow.” Very reactive, chemically, this element had little commercial use until World War II, when it was used to help make a nuclear-reactor fuel. Later, it was used as ingredients (fluorocarbons) in refrigerants and aerosol propellants. Most recently, it has found widespread use to make nonstick coatings for frying pans, plumbers’ tape, and waterproof clothing.

friction     The resistance that one surface or object encounters when moving over or through another material (such as a fluid or a gas). Friction generally causes a heating, which can damage a surface of some material as it rubs against another.

hydrocarbon     Any of a range of large molecules containing chemically bound carbon and hydrogen atoms. Crude oil, for example, is a naturally occurring mix of many hydrocarbons.

hydrogen     The lightest element in the universe. As a gas, it is colorless, odorless and highly flammable. It’s an integral part of many fuels, fats and chemicals that make up living tissues.

materials science     The study of how the atomic and molecular structure of a material is related to its overall properties. Materials scientists can design new materials or analyze existing ones. Their analyses of a material’s overall properties (such as density, strength and melting point) can help engineers and other researchers select materials that are best suited to a new application.

microscope     An instrument used to view objects, like bacteria, or the single cells of plants or animals, that are too small to be visible to the unaided eye.

molecule     An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

natural gas     A mix of gases that developed underground over millions of years (often in association with crude oil). Most natural gas starts out as 50 to 90 percent methane, along with small amounts of heavier hydrocarbons, such as propane and butane.

plastic     Any of a series of materials that are easily deformable; or synthetic materials that have been made from polymers (long strings of some building-block molecule) that tend to be lightweight, inexpensive and resistant to degradation.

polymer     A substance made from long chains of repeating groups of atoms. Manufactured polymers include nylon, polyvinyl chloride (better known as PVC) and many types of plastics. Natural polymers include rubber, silk and cellulose (found in plants and used to make paper, for example).

risk     The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)

Further Reading

Website: International Skiing History Association. Grip and glide: A short history of ski wax. https://www.skiinghistory.org/history/grip-and-glide-short-history-ski-wax

Article: C. Katz. Ski wax chemicals can build up in blood. Scientific American. March 15, 2011.