Four Different Grades of Stone Grinding
The Norwegian XC-team has introduced a color coding system to select corresponding skis and structure of the glide zone:
Fine Structures: Fine structures are mainly used on new snow and fine grained snow. For skating; fine structures are normally used from 0 °C (32 °F) and colder for classic;-5 °C (23 °F) and colder. Sharp crystals (present in dry new/fine snow) and a sharp structure is not optimal. A newly set (fresh) structure will in general give a “sharp” structure. In dry, cold, new and fine snow conditions (usually lower than -7 °C (19 °F)),the fine “sharp ” structure should be “rounded ” with Fibertex T264 ((or a plexi scraper). This process is normally more important for skating than for classic skiing. On the other hand, in new snow with high humidity close to 0 °C (32 °F) the structure should preferably be sharper.
Medium/Fine structures: This structure is a widely used structure. For skating it is used in most snow conditions normally from -7 °C (19 °F) up to wet snow. In very wet conditions a medium/fine structure combined with the use of an imprint tool has proven good results. For classic skiing we recommend this structure in new and fine grained snow (normally between -7 °C (19 °F) and 0 °C (32 °F)).
Medium/Coarse structures: Mainly for classic skiing on coarse moist snow and wet, glazy new snow between 0 °C (32 °F) and +3 °C (37 °F),a medium/coarse structure is preferred. This structure is also used sometimes in free technique (skating) on wet, coarse-grained snow. In this case, most racers would prefer to adjust a medium structure towards a more coarse structure by using a manual tool. Reference the table below for specific recommendations.
Coarse structures: This structure is rarely used in skating. For classic skiing it is used on coarse wet snow. Note! In general, it is better to use a somewhat finer structure than a structure too coarse.
Practical advice for the use of Swix manual structure tools
Linear, Broken and Screw structures
There are no exact rules when to use the different structures. Generally, we can say that linear structure and broken linear structure (V) are mostly used in classic races. Screw and cross-structures often give a good “feeling ” in free technique (skating) races.
Procedure then choosing structure
Use of the different imprint steels will vary with the underlying stone grind.
If the base has a fine structure it can be taken to “medium” by using the coarse imprint steel. In this way you will be able to make a fine stone grind fit “medium” conditions. However, it is not possible to make a coarse stone grind ‘fine’ with a ‘fine’ steel.
Also see Swix Structure Basics