Mix arrowroot with cold water until completely dissolved. Then add mixture to sauce or liquid to be thickened, stirring constantly with a wire whisk (if adding to liquid only) or a wooden spoon (if adding to liquid with chunks) until it reaches desired consistency. Generally speaking, the real thickening happens when boiling temperatures are reached. Keep in mind it will continue to thicken slightly even after removed from heat, so keep stirring for a couple of minutes to be safe. One tablespoon of Arrowroot will thicken one cup of liquid or is the equivalent of 2 tablespoons of flour thickeners.