Thursday, March 19, 2015

Enhancing the Stone

You hear about it when you watch curling on TV at major events. It's about "enhancing/papering  the stones". What is it and why is it done? Well, sit back, I'm going to pull back the curtain and  explain why and show you how it's done.

If you read my recent blog entitled "Guiding Rocks Down The Ice", you were offered an explanation of why stones curl in the first place. If you've not read the blog, I suggest you do so and return here. I'll wait!

OK, welcome back, I hope my attempt to explain why stones curl makes sense to you. It's all about the texture of the running surface on the pebbled surface of the ice. I used the word "grab" in blog that you just read, perhaps not the most scientific way to explain the action that takes place between the running surface and the pebble but it seems to work for many.

As you can appreciate, over time, the running surface can become well worn, (i.e. smooth) and as that occurs, there's less "grab" (there's that word again) and as a result, there's less curl and the last time I checked that's what the game is called, curling!

To make the stones finish more "aggressively" (i.e. late curl), the texture of the running surface of the ice is "enhanced" (how's that for diplomacy?). The process to do so is sometimes referred to a "papering" because a waterproof, 80 grit carbide silica emory paper is the agent of change.

Here's how the ice technician (I.T.) does it. The I.T. carefully places the stone onto a block where a piece of the aforementioned emory paper is placed. As you can see in the photo, the handle of the stone is placed at the 12 o'clock position as it is slid over the emory paper, approximately the distance of the diameter of the running surface then returned to its original position.

The stone is lifted once again from the emory paper and returned but with the handle in the 10 o'clock position. It is then slid forward and returned. The stone is then lifted and returned with the handle at the 2 o'clock position, slide forward and returned.

You can see clearly the "textured" running surface (photo below)) as it's removed from the emory paper.  It's a rather vivid grey colour as the "granite dust" from the abrasive running surface is quite visible. But, of course, that granite dust, for obvious reasons, must be removed and that's accomplished with a clean cloth dampened with naphtha gas. A fresh piece of emory paper is used for each stone!

The papered/textured/enhanced stone, on an excellent ice surface, will finish (i.e. late curl). It makes for great shot-making for TV events but with all due respect, if recreational curlers played on championship ice with textured/papered stones, it would very likely be a frustrating experience because under the conditions just described, the ice and stones are not very forgiving! A curler playing under said conditions must have precise weight control as the stone, delivered with an inappropriate weight, can make you look pretty foolish!

Although the process, as you can see, is pretty simple, the effect does not have a long shelf life.  The important point is this, the stone must be moved over the emory paper in full contact  with the paper. It's so easy for a portion of the stone to lift from the emory paper resulting in an uneven texturing and that would not be a good thing. This procedure should only be done by someone who is experienced. It's not for a well-intentioned club member who has seen the procedure on some blog site ! :)

It's not uncommon for the ice technicians to re-paper the stones during a prolonged event. It's not a procedure used in most curling facilities. but if your ice technician or ice committee suggests papering the rocks at your curling facility, it's a good idea to support the idea. Remember, the game is called "curling"!

To see the process in action, go to my Facebook home page!


  1. Bill, after reading the "enhancing the stone" blog, it explains why top curlers spend so much time at their events testing rocks, if time is available. It would seem past history, or booking rocks, is less important. If a club IT is sanding regularly, the previous knowledge the better curler would have is less effective as he/she struggles with "funny" stones for a few ends. We even saw this at the latest World's in Halifax despite more practice time. Let me tell you...a lot of our better club curlers are not happy with the sanding. (I'm assuming our IT has been trained). I was interested to read Ed Werenich's unfavourable comments about this, as well as his comment about the overactive rocks at top level events. Maybe you could also comment about the technique used to sharpen the hitting edges.

  2. Hi, Coach Bill, This is an awesome informative article about enhancing the stone.Your article fill with many information.Thanks for sharing with all us.