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Rockology 101 - Part II, the running surface

Editor: Chris Daffern
Date: 2014-02-09

Each side of a curling stone (top and bottom) has a concave area commonly referred to as the cup. The edge of the cup is appropriately named the running surface, and it is this thin edge that actually contacts the ice.  (Over the course of a season, an ice technician may remove the handle, flip the rock over, so the top cup becomes the bottom and there is a newer running surface.)

The running surface is not polished like the rest of the stone, but is comparatively rough. For curling to be played as we experience it, the running surface must never be allowed to wear smooth or to be damaged.

With curling stones, the running surfaces will wear and may become pitted.  They may get too wide or they may be too narrow.  The ideal running surface is just 5.6 to 6.0 mm in width.  Smaller running surfaces put more pounds per square inch on the pebble; this usually results in good curl but slow ice.

Varying running surfaces may be the cause for some rocks to be inconsistent.  Some curl, others run straight or don’t curl as much.  What can you do about this?  Probably not much - directly.  When rocks get that bad, ice techs. may recommend resurfacing or texturing the running surfaces.  That’s when the cost can begin to hurt.  Reconditioning both sides of a set of 16 stones (just one sheet) costs about $2,080.00, say $21,000+. 

Installing inserts into the base of stones costs about $4,200 for a full sheet; say $33,600+/-.

In the worst case scenario when the rocks are beyond economical or feasible repair, a new set of curling stones will cost about $10,400; say $83,200 +/-.

So what can you do?  Do not wear your curling shoes outside of the Club.  Dirt and grit on the ice kills rocks.  Even walking from the dressing rooms to the ice surface brings dirt from the floors/carpets with them.

How to fix this?  Avoid walking through public lobby areas where sand, dirt, grit and rock salt accumulate.  Even better, carry your shoes with you to the ice surface or wear slippers over both shoes.  (That also helps keep the soles of your feet cooler and mitigates against hot feet that melt the ice surface.)

Observe the elite, competitive curlers enough and you will see they are very conscious about running surfaces and matching rocks.  They inspect the running surfaces carefully.  It really does matter!

Playing Note: Instructors usually encourage players to put a “positive rotation” on the rock when it is released.  This means about 2 1/2 to 3 full rotations down the ice.  Anything less, particularly with sharpened, i.e. textured, stones and you risk losing the rotation and who knows what will happen with your rock then.  A good, clean release with a positive rotation but not a spinning stone.  Spinning stones tend to be released with more weight, often because they have been pushed rather than cleanly released and they tend to run straight rather than move or curl in the desired direction.

It’s the icemaker’s job to ensure the ice we curl on is gleaming, scraped, pebbled and ready for us to play on.  That includes looking after our rocks.  But it doesn’t all happen by magic.  It takes hours of effort and a whole lot of know-how to create the excellent playing surfaces we enjoy every week.  So let’s all resolve to support their efforts and do our part; including taking care of our ice and rocks.

In our series on curling etiquette, the word that comes up over and over is “respect”.  Respect your club, respect your ice and rocks.  At the end of the day, it will save us all money.

Rockology Part I started with excerpts for the lyrics to Abba’s song “Rock Me”.  Just to keep the lyrical tone, I’ll finish with these words written and sung by Andy Kim:

“Rock me gently … Rock me slowly … Take it easy … Don’t you know that I have never been loved like this before …”.

(Sources:  the Canadian Curling Association website, Canada Curling Stone Co., the Ontario Curling Association’s Ice Technician’s Reference Manual 2013-2014 and “Curling For Dummies” by Bob Weeks.)

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