Two summers ago, I took a basic soapmaking class at a local soap supply store. After making my first batch in class, the compulsive do-it-yourselfer in me knew I had to buy the ingredients to make more soap at home. My first solo attempt at lye soap, made at home in my parents' kitchen, was scented with orange essential oil and had swirls of cocoa through it (because I heard chocolate was a good emollient). I was so confident in my abilities, I made a double batch of soap of orange-chocolate soap. Unfortunately, I failed to take into account the fact that it would literally take my husband and me two years to use all of the soap from that first batch (even though it is really recommended that you use homemade soap within a year of making it because it has no added preservatives). I did give several bars to my grandmother, who is now hooked on it because it doesn't burn the sensitive skin of her face. Now, finally, we are down to our last couple of bars and I can justify another batch.
The process that occurs when soap is formed, when fats mix with the alkaline lye, is called saponification. Handmade soap is made through a different process than commercially produced soaps. The method of soapmaking I learned is called "cold process," where saponification takes several days and glycerin, a biproduct of saponification, is left in the finished soap. Glycerin is an emollient that is beneficial to the skin, and it is frequently removed from commercial soaps. (Norma Coney, The Complete Soapmaker: Tips, Techniques & Recipes For Luxurious Handmade Soaps).
I will say that buying soapmaking supplies is a rather hefty initial investment. Because the recipe I used is from The Soap Barn Co., LLC (see Note below) and is probably proprietary, I won't post it here. There are numerous websites, however, with free basic lye soap recipes, like the one found here. Coconut oil and palm oil may seem pricey, but they really do make beautiful, richly-lathering bars. I bought bulk amounts of both and still have oil left after three full batches (almost 10 lbs. of soap). Handmade soap in specialty shops usually costs more than $5 per bar and you can make your own for a fraction of that price, depending on the type of oils and additives you use. I should also say that, as the name suggests, making lye soap requires the use of, you guessed it, lye (a.k.a. sodium hydroxide). Lye, when mixed with water, creates an alkaline solution that can cause burns if it comes into contact with exposed skin (if you've seen the movie Fight Club, you know what I'm talking about). The fumes that are produced when the lye and water are combined can also be irritating, so don't inhale them. When you purchase lye, be sure to read all safety instructions before working with it and wear appropriate protective gear. Besides, rubber gloves and safety goggles really get you into the mad-scientist spirit of soapmaking, and that's half the fun!
First I prepared my mold, which was just a clear, plastic, shoebox-sized container. I used a cheap garbage bag as a liner for the box. Then I measured the lye into a plastic pitcher and combined it with the appropriate amount of water, according to the recipe I was using; once mixed, the solution heated up rapidly. While I waited for this to cool down to the correct temperature (I've read temperatures ranging from 80 degrees Farenheit to 110 degrees Farenheit, so again follow your recipe; my target temp was 80 degrees), I measured the oils into a stainless steel pot. The alkaline mixture can corrode some metals, so use caution when choosing a pot to mix in (I got my stainless stockpot at The Salvation Army Thrift Store for the sole purpose of soapmaking); use either stainless or enamel. While the lye solution was still cooling, I heated the oils to the appropriate temperature. The idea is for the lye solution and the oil mixture to be the same temperature when combined. When the temperatures were correct, I slowly mixed the lye solution with the oils using a rubber spatula, then it was time to stir. You can stir by hand, which takes a L-O-N-G time, or use a handheld mixer or immersion blender (my personal favorite). Using my stick blender, I mixed the soap until "tracing" occured (or "trailings" appeared), which essentially means that when a spoon is drawn through the mixture, lines will stay on the surface of the mixture, remaining distinct. Sometimes this is subtle and requires a careful eye to see, although with a stick blender it happens rather quickly. Once trailings appeared, I mixed in my essential oil (I used lemongrass) and poured the contents of the pot into my prepared mold. I snapped the lid onto the plastic shoebox, wrapped it in a blanket and put it upright in the closet, so it would be out of the way in our small space. Insulating the soap with a blanket slows down the rate at which it cools, preventing it from separating.
I allowed the soap to sit, covered and wrapped in a blanket, for a full day. Then I uncovered the mold and left it exposed for another day. After the second day, I pulled the block of soap out of the mold and cut it into bars. The size, and even shape, of your bars are a matter of personal preference; I made generous 4 oz. bars that measure about 2" x 3". The bars will need to cure for several weeks. I stood mine up vertically (as pictured) on a wire rack and will leave them to cure for probably 4 weeks. In about a month, my husband and I will have beautiful, lemongrass-scented soap.
Note: The Soap Barn Co, LLC is an admirably socially and evironmentally conscious business. I enthusiastically encourage anyone in the Genesee County, MI area to take a class with Ms. Grant or stop by her store to be inspired by the many oils, additives, and prepared soaps. For those who are not in the Gen. Co. area, supplies may be ordered through The Soap Barn Co.'s website at http://www.thesoapbarn.com/ and shipped to you. Once you learn the basics of soapmaking, there are endless combinations of essential oils, fragrance oils, herbs, flowers, etc. that can be used to make your uniquely perfect bar of soap. Be creative and enjoy!