What is pebble on curling ice?

Pebble is a layer of frozen water droplets sprayed onto the sheet before play. The stone rides on the tops of those droplets rather than on the ice itself, which is what lets it travel a long way and curl at all — on flat ice a stone would grip and stop almost immediately.

Why is curling ice pebbled?

Because a 19-kilogram stone on a flat, smooth surface behaves like a suction cup: the contact area is too large, friction is too high, and the stone neither runs nor curls. Pebble reduces the contact to a few dozen tiny points, which cuts friction dramatically and gives the stone the asymmetric grip that makes it bend.

What temperature is curling ice?

The ice surface is typically held somewhere around −5 °C, with the air above it warmer and, crucially, dry — the dew point has to stay below the ice temperature or frost forms on the sheet and slows it down.

How often is curling ice re-pebbled?

Before every game, and often between games on a busy day. Pebble wears down as stones and brushes pass over it, which is why a sheet gets keener through the first few ends and can slow again late.

CurlTi.me/Learn/Making ice

How curling ice is made

A curling sheet is not frozen water that somebody flattened. It is a manufactured surface, built in layers over days, and the part the stone actually touches is a field of frozen droplets with their tops shaved off.

Last updated 2026-08-16

It is not hockey ice#

The most common assumption about curling ice is that it is a hockey rink somebody swept. It is nearly the opposite. Hockey ice is soft, wet at the surface, kept relatively warm, and deliberately smooth. Curling ice is colder, harder, obsessively level, and then deliberately roughened with a layer of frozen droplets before anyone plays on it.

That last step is the one that makes the sport possible, and it is worth understanding before anything else.

Pebble: why the stone never touches the ice#

A curling stone weighs 19 kg and it does not slide on the flat. Put one on a smooth sheet and you have essentially a suction cup: the contact area is huge, the friction is enormous, and the stone travels a few metres and stops without curling at all.

So the sheet is pebbled. An ice technician walks the sheet with a tank on their back and a spray head, swinging it in a steady arc, and lays down a fine mist of warm water that freezes on contact into thousands of small domes. The stone then rides on the tops of those domes, and its real contact area drops to a scatter of tiny points.

Why the stone runs. Its running band — an annulus about 13 cm across, not the whole base — rests on the flattened tips of the pebble. The ice surface underneath is never touched.

Two details matter. The stone's underside is not flat either: it touches through a narrow running band, an annulus roughly 13 cm across, not the whole 28 cm diameter. And after pebbling, the tips are shaved level in a pass called nipping, so the stone meets flat tops rather than round domes. Nipping is what turns a rough surface into a fast one.

Pebble is also why the ice changes during a game — the tips wear and polish, the sheet gets keener, and late on the band can start riding on more of each bump and slow down again. See ice speed.

Building a sheet, from the concrete up#

Making ice for a season takes days. The order is fixed, because each layer has a job that the next one depends on.

A sheet in section. Everything above the concrete adds up to roughly 25 millimetres, and every millimetre of it is put down deliberately.

The slab. A concrete floor with refrigeration pipes cast into it, over insulation. The pipes carry chilled brine or glycol, and they are what actually holds the temperature — the ice is simply frozen onto a cold plate.
Base ice. Water is applied in very thin floods and allowed to freeze completely between passes. Thin and slow is the entire technique: a deep flood traps air and freezes cloudy and soft.
Paint. Once there is a solid white-painted base, the rings and lines go on. They are painted onto the ice, not under it, and then sealed with more thin floods so that nothing is playing on paint.
Playing ice. More floods on top of the seal, building up to the final thickness.
Levelling. The surface is scraped flat, checked, and scraped again. Championship sheets are levelled to within a millimetre or two across the whole 150 feet, because a low corner is a permanent fall that every stone will drift toward.
Pebble and nip. Immediately before play, and repeated between games.

Temperature and humidity#

The ice is only half of it. The air above it decides whether the sheet stays the way it was made.

What	Roughly	Why it matters
Ice surface temperature	around −5 °C	Colder ice is harder and keener; warmer ice is slower and takes damage from stones and brushes.
Air temperature above the sheet	cool, and stable	Swings in air temperature change the surface faster than the refrigeration can respond.
Dew point	below the ice temperature	This is the one that ruins games. If the dew point rises above the ice, moisture condenses onto the sheet as frost, and frost is drag.
Water for pebble	purified, and warm	Dissolved minerals make cloudy, soft pebble; warm water forms rounder domes that nip flat properly.

This is why a curling club has serious dehumidification and why arena events fight the crowd all week: several thousand people breathing raise the dew point, frost forms, and the sheet slows through the closing ends of a game.

What happens between games#

The turnaround is a routine, and a fast one:

Scrape. A wide blade takes off the worn pebble and any damage, and levels what is left.
Clean. The shavings are removed and the surface is mopped, because anything left behind becomes a pick — a piece of debris that grabs a stone mid-slide and sends it somewhere nobody called.
Pebble. Usually two passes, walked in opposite directions, so the droplet pattern is even.
Nip. A light blade pass to flatten the tips.

Pebble head size, water temperature and the walking pace are all levers the technician uses to make the sheet faster, slower, straighter or swingier. A good ice technician can hand a competition the ice it asked for, which is a genuinely under-appreciated craft.

Picks, and why they are unfair#

A pick is a fragment of something — a hair, a thread from a glove, a fleck of ice — that the running band catches. The stone changes direction sharply and immediately, and nothing can be done about it. There is no rule that fixes a pick, because there is no way to prove one happened.

This is why curlers are told not to wear anything that sheds, why brush heads are checked, and why the sheet is mopped between games. It is also the honest answer to why a shot sometimes goes nowhere near where it was thrown.

How this is modelled in the game#

CurlTi.me does not simulate individual pebble domes — it simulates what they produce. The friction law µ(v) = 0.00662 + 0.00231/√v is a fit to measurements taken on real pebbled ice, and the ice presets scale it. The sheet's break-in over the first few ends and its slowdown late are modelled directly, because they are what a player experiences.

Picks are not modelled at all, deliberately. An unpredictable, unattributable event that destroys a shot is interesting on real ice, where nobody chose it; in a game it just reads as the software cheating.

What that ice does to your shots The equipment that goes on it