The most common ways of making soap are listed below.
Cold Process
This is likely how grandma made her soaps. Essentially, a mix of lye and some fatty acid (bacon grease, beef tallow, olive oil) is combined with some water and then a chemical reaction occurs (saponification). This is a slow time consuming process that can take over a months time to complete.
Hot Process
Hot soap-making processes are essentially a quicker version of the cold process, using heat to expedite the process.
Melt and Pour
This is by far the easiest method, taking a base of clear soap, melting it and pouring into molds. Different effects can be achieved with the addition of other ingredients such as essential oils and herbs. This is our recommended method for today's amateur soap makers.
Rebatching or Soap Recycling
This is done by grating a soap bar and then heating the shavings over the stove with some liquid (usually water). Then add coloring agents and scented oils to the batch and you have in essence, new soap. Also known as soap recycling process.