The process varies at each site depending on size and type of rink, the water source, the site itself and the existing conditions. A couple of rinks are made on parking lot(s) pavement, but most of are made on turf.
The rinks made on pavement are able to be skated on earlier because none of the water sinks into the ground. However, the downside to pavement is that the sun shines through the ice to the blacktop. This warms the pavement thus melting the ice or slowing the freezing action.
For the rinks on turf, the area must be flat, FROZEN and have little or no snow on it – or the snow must be packed down (to be used as a base). Unfrozen ground just lets the water soak in. Temperatures must be consistently cold to freeze the ground. Once frozen, the water remains on top of the ground. Depending on the site, crews spray water on the ground and allow it to freeze. Depending on the temperatures, crews may be able to stay out and keep adding water to some areas of the rink while the just-watered areas freeze. Lighter coats of water are used to help the water freeze faster. Under good conditions, the worker will spray water while walking backwards for hours and hours. Eventually, dozens (then hundreds) of light coats of water turn into "skateable" ice.
Each site varies and is unique to how long it takes to become safe. Generally, it can take a week (5 to 7 days) or so to build up enough ice for safe skating.