Hot process
In the hot-process method, lye and fat are boiled together at 80 – 100°C until saponification occurs, which before modern thermometers, the soap maker determined by taste (the bright, distinctive taste of lye disappears once all the lye is saponified) or by eye; the experienced eye can tell when gel stage and full saponification have occurred. Beginners can find this information through research, and classes. It is highly recommended to not "taste" soap for readiness. Lye, when not saponified is a highly caustic material. After saponification has occurred, the soap is sometimes precipitated from the solution by adding salt, and the excess liquid drained off. The hot, soft soap is then spooned into a mold. The soap lye is processed for recovery of Glycerine.