How to Make Basic Lye Soap

I have been a soap maker on and off for many years. I enjoy making lye soap of all kinds, and I have several books and recipes for this wonderful craft. Although I have lard, lye and all the necessary tools for making soap on hand, I have not made soap for years–until recently.

It is all due to my daughter, Joy. She wanted to learn to make soap. When she visited earlier in the year, she brought more lye and insisted I show her the process. I had forgotten how pleasant a task soapmaking is, and have included it in my schedule – I will now make soap more often!

Simple lye soap is simple to make. There are recipes all over, but the one I use is this:

  • One 12 oz. can of 100% lye
  • 21-1/2 oz. distilled water or rainwater
  • 5 lb., 7-1/3 oz. lard

It’s “easy as pie” to make soap with these three ingredients. You can change the liquid to add powdered milk, fresh cow milk, goat milk, sheep milk or any exotic milk you can get your hands on. You can adjust the lard to any kind of fat – vegetable oils, almond oil, shortening, coconut oil. Think of an oil, a fat, and you can use it. The recipe is very forgiving.

Soapmaking Kits from Lehman's

Soapmaking Kit

Before you begin, please take some precautions. Do not make soap with small children or pets nearby. You do not want any distractions or danger of spillage, as the lye is caustic until saponified. Use only a glass bowl for the lye and water mixture, and mix it in a well-ventilated area. Do not breathe the fumes from the water and lye mixture.

First, put the water in a glass bowl large enough to hold the liquid without worry about splashing out. The most dangerous part is adding the lye to the water. The powdered lye is slowly added to the water and stirred with a wooden or stainless steel spoon. DO NOT ADD WATER TO THE LYE. Also, don’t breathe the fumes – have a window open or work in a well-ventilated place. After mixing, let the lye water cool to about to about 85º.

While this is cooling, heat the lard to melt and then cool to a like temperature – the lye and lard should be very close in temperature. The lard needs to be in a stainless steel or glass container. I have some lovely stock pots and can use one of them for my soap.

Once the two temperatures are nearly equal, you very gently, very slowly pour the lye water into the warm oil. You need to stir with the spoon slowly, in a figure 8, until the two mix together. This, to me, is the magic time – it is called “saponification” – the combining of the fat and the lye into a totally different substance … soap.

Stir slowly until the mixture becomes like a pudding .. there will be a trace of “dribble” as you move the spoon around and lift it to dribble and test. This is the time to add your fragrances – make sure they are essential oils. Color can also be added and extras, like oatmeal, etc. … the color has to be soap “approved,” not food coloring.

Our first batch had coconut oil as well as putting some lavender essential oil in at this point.

Time-Saving Plastic Soap Molds from Lehman's

Time-Saving Plastic Soap Molds

Of course, before you have started, you have your molds. Glass, wood – with wax or parchment paper or material as a lining – or even plastic. I have used a cake pan with parchment paper but tried and liked plastic soap molds and will probably continue to use them. I was worried that the heat of the lye (it stays hot for several hours) would melt the plastic, but it didn’t.

So now you have your soap ready to pour into your molds. If you need to cut, you cut within a few hours or the soap will become too hard and will crumble with cutting. If you use a pre-formatted small mold, then you can pop it out in about 24 hours.

Put the mold, covered with a towel, in a quiet place. The soap needs to cure for about a month or so. I figure it’s safe to use in about 3 weeks, but usually plan on a month to be on the cautious side.

If the lye-oil mixture is correct in amounts, there will be no lye “oozing” out of the soap. If the lye is too strong for the oil, then you will have a powder on the soap that you can scrap off. That is excess lye and needs to be disposed of safely. If you have too much oil for the lye, it will take much longer for the soponification to reach and you will have to stir your soap much longer. (Love that word … it trips off the tongue so pleasantly.)

Lye soap has a bad reputation. Many mentions are made of Grandma’s homemade soap making your hands red and rough and burning your body. I feel that is because the soap has not cured yet or Grandma put too much lye in it. Properly made, it’s great for skin, hair and laundry.

Which brings me to a wonderful side-line of my soap. Besides using it in the shower (I use it for my hair and rinse with cider vinegar), I have made my own laundry soap. I took the ugly bars, mis-sized, mis-shaped (after the month’s waiting, of course) and chopped them into rough pieces and soaked overnight in water. Then chopped them up in my food processor, adding water to make a sloppy paste. It sits in a covered ice-cream bucket by the washer. A small scoop–about 1/8th of a cup–of the paste in the water as the washer fills with a jiggle of washing soda added makes the clothes very VERY clean. I use white vinegar in the rinse water because the soap seemed to stay in the clothes and give them a soapy feeling. But the vinegar gets the soap residue out wonderfully. If there is a stain, I will rub the stain with the paste before putting it into the washer. Even some old stains are now coming out. Hanging out the laundry is so pleasant with the hint of vinegar smell and the clean, CLEAN feel of the clothes!

Since my daughter won the “fight” about starting to make soap again, I have decided to never turn my back on it again. Joy is making her own soap, experimenting with scents and colors, but I am content with the straight, simple recipe. I have even managed to sell some of the bars at some of my historical events, as they are totally “period correct.”

So, follow the right precautions, and have fun crafting your very own soap – just like Grandma used to do.

About cpthegreat

Connie (aka Spinning Grandma) lives on Ash Lane Farm in southwest Minnesota. She is an expert on spinning, weaving and knitting and a former history interpreter.

5 thoughts on “How to Make Basic Lye Soap

  1. This has inspired me to try my hand at soap making. However, the directions seem to be missing the part about heating the water. I assume the water should be brought to a boil?

  2. Oh, Maggy– I hope you do NOT heat your water! The Lye will do it for you. It gets plenty hot from the reaction. That isn’t mentioned above, and possibly should have been. Be safe– read ALL you can about soap making before trying it. It isn’t difficult, but don’t jump in headlong, OK? Lye can be dangerous to work with, but you can indeed avoid danger by handling it properly. Good luck and have fun!

  3. No, the water should not be boiled. I use distilled water in my soap. When you add the lye, the mixture will reach potentially dangerous tempatures. Add lye to water very slowly and very carefully in a fully ventilated area. Slowly stir the mixture until the lye dissolves and allow the mixture to cool to close to the same tempature as the lard mixture as the author states. If the lye does not cool quickly enough you can place your container in a sink with cold water or cold water and ice for a few mintues to speed it along. BE VERY CAREFUL to not allow the mixture to tip, tilt or spill if you attempt to cool in in this manner.
    Enjoy! Soap making is wonderful hobby. If you would like a visual tutorial, there are a few on U-tube using other recipes.

  4. I believe it’s liquid ounces, as you would measure in a standard measuring cup.