Note that there is a difference in freeze branding and "freeze marking" since freeze marking provides an individual identifier for each horse, rather than a "farm or ranch" identifier (e.g., lazy R). Freeze branding destroys the color-producing cells in the hair follicles. The result is white hair in the branded area. To freeze brand a horse, clip the area to be branded and wipe with alcohol to ensure a clean surface. A copper brand (copper holds the coldness better than iron) is submerged in dry ice and alcohol and cooled to minus 100 degrees F. The brand is held on the horse for approximately 20 seconds. The thickness of the horse's skin, age and color can have an effect on the time needed for a good freeze. When the brand is removed, the surface area of the brand should be plainly visible and clearly frozen. If it is not, hold the brand on for another 5 seconds. The area will swell in approximately 30 minutes, and hair will start to slough off in 3-4 days. White hair will begin to appear in 6-8 weeks. The horse will have very little discomfort during the process. Liquid nitrogen can be used instead of dry ice and alcohol. Liquid nitrogen has a temperature of minus 320 degrees F. Therefore, when using liquid nitrogen, the branding time should be cut in half (10 seconds).