About Stone Grinding
The single most important factor in ski speed is matching the ski to the skier and the conditions.
The use of proper grinding technique will result in a flat base with fresh, open surface for wax absorption, and in a structure suited to the prevailing snow conditions. Given proper ski selection, the factors that determine speed are:
"Structure" refers to small grooves that are put into the base through rilling, brushing or stone grinding. These grooves relieve the adhesion caused by the presence of water.
The absence of "hair" results in faster ski. Fine hair can be caused by sanding, wire brushing, poor grinding or polishing. Lack of smoothness can also be caused by scraping base that has become hard through overheating, or by inexperienced steel scraping.
"Wax absorption" is affected by the condition of the base surface. Bases can easily be clogged by snow-borne pollution, by dust in storage, or by chemical wax removers. The surface layer of a base can be melted by ironing at too hot, sealing the base, or by too aggressive grinding. All this results in rapid wax wear,and the familiar gray spots along the base. New skis frequently suffer from bases partly melted during factory grinding, compounded by oxidation during storage and topped off by dirt accumulated in the warehouse.
Lack of flatness can be caused by wear, poor scraping, warping due to overheating and often to the manufacturing process.