Master Batch Soap Making


First of all, I want to say that anything you could ever think of, someone else, somewhere else, has already been doing for a very long time. I don’t claim to have invented these methods. I’ve taken bits of information that I’ve learned from others, combined them with my own experiences (sometimes mishaps that became blessings) and devised a method that worked best for me.

I made soap the same way for the first few years – melting each batch and waiting for it to cool, patiently waiting for the lye water to reach the same temperature as the cooling oils. When you have several soaps to be made, this process can take hours, even days to complete. One morning, I ran across an article in a small publication about a soap maker who had been making soap for several decades. He found the “temperature thing” totally unnecessary and a waste of time. Soon, I discovered other soap makers were discussing this method called RTCP: Room Temperature Cold Process.

To put it simply, RTCP is the act of premixing your oils and allowing them to cool to room temperature. Separately, the lye water is premixed, allowed to reach room temperature then simply mix the two batches together when its time for making soap.

The thought of having lye water lurking around unattended did not appeal to me. So, I decided to experiment with taking this method to another level. On the first day, I made what I now refer to as a “Master Batch”.

The Master Batch recipe will give you enough base to make five full loaves of soap; each loaf creating twelve, four ounce bars when fully cured.

Additional equipment for the Master Batch Recipe –

Empty, clean five gallon bucket
Large canning pot for melting (23 quarts or more)

Master Batch Recipe:

7 lbs. 8 ounces Vegetable Shortening*
3 lbs. 2 ounces Coconut Oil
3 lbs. 2 ounces Olive Oil

*Vegetable shortening varies in different parts of the United States. Some regions have a partial cottonseed blend which shouldn’t affect your soap at all. Crisco-type shortening is a good alternative. Just be sure to read the labels carefully when doing your shopping — many shortenings contain beef fat or partial beef fat. This master batch recipe calls for all-vegetable shortening.

Measure Olive Oil into your empty five-gallon bucket and set aside. Now measure your vegetable shortening and coconut oil into your large canning pot and melt on the stovetop on medium-low. When fully melted, carefully pour the contents into your waiting bucket of olive oil. (It’s best to place the bucket of olive oil on the floor to avoid any mishaps). Now, stir with your stick blender until fully mixed. I use an electric drill with a paint stirring attachment for blending the master batch. As the batch cools, repeat the stirring process whenever you get the chance and allow to cool overnight. The next day, give it a final, vigorous blending until the mixture looks fully incorporated. The final master batch will have a runny, pudding-like quality to it. You now have five full batches of soaping oils ready to be measured out individually and turned into soap.

Master Soap Recipe:

2 lbs. 12 ounces master batch
13.5 ounces water
6.2 ounces lye

Here is where the time-saving tips come into play — when making soap, I don’t wait for anything to cool, wait for a certain time to color my batch or try to figure out when to scent the batch. Using the same safety guidelines listed in the Standard Soap Making Instructions (goggles, gloves, respect for the lye, etc.) here is the way I normally make soap.

1. Measure 2 lbs. 12 ounces of master batch into a 3 gallon bucket.
2. Weigh 13.5 ounces of water into my lye pitcher then slowly add the 6.2 ounces and lye and stir until dissolved.
3. Add colorant (usually oxides) into master batch and stir with stick blender until fully colored.
4. Add any botanicals / additives the recipe calls for.
5. Weigh and measure essential oils and add to the master batch, stirring again.
6. Slowly pour the hot lye water into the 3 gallon bucket of colored and scented master batch and begin mixing with stick blender. Trace usually takes approximately five minutes before it’s ready to pour into the molds.

Basically, what I have done is streamlined every step that was time-consuming, turning the operation into a smooth day of batch-after-batch soap making. Pretty easy, huh?

DO NOT skip over anything that is a safety precaution! Wear your goggles and gloves, remember that lye is corrosive and don’t forget to hold your face away from the pan while mixing. Remember to keep your stick blender immersed in the soap you are blending and don’t splash around. Don’t forget — you add lye to water, you do NOT add water to lye. (The snow falls on the lake, remember?) Your eyesight and the safety of your children and your pets are more important than any batch of soap. If you remain aware of what you are doing and do it with thought, you’ll be fine. Simply pay attention to what you’re doing and it will be as easy as baking a cake.

You are ready to tackle a variety of recipes using the same “base” of oils that we have called the “Master Batch”. Later on, we’ll try some recipes that require the use of different oils and luxury additives. In the meantime, the recipes that follow are some really great soaps! Each of these recipes was poured into molds with inside measurements that were 15 ½ inches long, 2 inches deep and 3.75 inches wide. This is based on the molds the I used in this process. You can use molds that are slightly larger, but keep in mind that the soap bars will be thinner. Any smaller and you’ll have leftover soap to pour.

For determining how much oil to use for the soap mold YOU have, see our article on CALCULATING SOAP BATCH AND MOLD SIZE.

The two master batch recipes below are examples. You can create a wide variety of soap by simply switching essential oils, or replacing with fragrance oils or experimenting with a variety of colors and spices.


This bar is great for anyone that loves citrus scents. This particular soap takes a little longer to trace and the addition of calendula petals make pretty yellow flecks throughout the soap. Soaps with all citrus oils have a tendency to “lock in” the fragrance when cured. Meaning, the bar doesn’t seem to smell very strong but does when you get the soap wet in the bath or shower. If you’d like to anchor the scent a little more, replace ½ ounce of the sweet orange essential oil with patchouli essential oil.

2 lbs. 12 oz. master batch
13.5 oz. water
6.2 oz. lye
1 oz. pink grapefruit essential oil
1 oz. sweet orange essential oil
1 oz. 5-fold orange essential oil
3 tablespoons calendula petals
1/16 teaspoon yellow oxide colorant
follow soap making instructions….


The reason I call this bar “sunshine” is the fact that it is a great scent to wake up with. The peppermint helps to wake you up in the morning while the citrus oils bring about a cheerful mood to start the day with.

2 lbs. 12 oz. master batch
13.5 oz. water
6.2 oz. lye
1 oz. pink grapefruit essential oil
1 ½ oz. sweet orange essential oil
½ oz. peppermint essential oil
1 teaspoon peppermint leaves
1/16 teaspoon fluorescent yellow pigment
follow soap making instructions….

For more information on soapmaking, purchase my book, MAKING SOAP FROM SCRATCH, from aromaG’s Botanica here, or from here.

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