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Formulating goat milk soaps and using additives

Formulating goat milk soaps and using additives

Our last soap blog showed a step-by-step tutorial on how to make goat milk castile bar soap.  Castile soap – 100% olive oil soap – is mild but not very bubbly or cleansing.  What do we consider when formulation goat milk soap with multiple triglycerides? And what about adding scents and colors to goat milk soaps?


The types of oils or fats to use in your soap depend on a multitude of factors.  What will you be using this soap for?  What types of oils do you have on hand?  Which oils can you purchase at a reasonable price?  Which ones have a good shelf life and which ones will cause early rancidity?  Besides these practical and economic factors, there are also ethical, aesthetic and ecological considerations.  If you are selling soap, you also need to factor-in the sensibilities of your intended customers.


For example, I do not use palm oil at all because of the effect on deforestation, which contributes to climate change and reduction of the orangutan’s habitat.  Sustainably harvested palm oil does exist though, and many eco-conscious soap makers choose that route instead.  I decided that palm oil is just a cheap ‘filler’ in soap; I can get the properties I want using a combination of other vegetable oils and butters, like shea and cocoa butters.  These are expensive, but so is sustainable palm oil.  Again, it comes down to personal choice.


Using lard (pork fat) or tallow (beef fat) can be a wonderful way to utilize the whole animal, so nothing goes to waste.  Also, lard can be an excellent substitute for palm oil.  However, lard or tallow soaps are not popular with vegetarians, people from religions that forbid using certain animals, or those that simply do not want animal fat in their skin care products.


Here are some very specialized goat milk soaps.  They are shaving soaps and are formulated for a very creamy and long lasting lather.  The lather stays foamy for about fifteen minutes – the time needed to shave.  Bentonite clay is also added for extra razor slip.  These soaps have very low cleansing value but high conditioning value.  The soap shape is also designed to fit in most shaving mugs.  This is meant to illustrate soap formulation for a very specific purpose, which is to shave, not to cleanse.




Soaps intended for bathing or showering would be formulated differently, they should be more cleansing and the lather need not be so long lasting.  An easy way to make goat milk bath soaps with great bubbles and good cleansing action is a simple blend of coconut and olive oil.  Play around with the percentages until you get the properties you want in  Just remember that the lather will be creamier and the soap milder than what you get from the numbers.  This is because the program only takes into account the oils-triglycerides used in the soap and not the liquid used to dissolve the lye.


Scents and colors are considered additives in soap.  Strictly speaking you do not need them, but scented soaps are well liked, and scented goat milk soaps can be quite luxurious.  Scents can come from fragrance oils, essential oils or a combination.  I have also had success infusing cinnamon in olive oil and then using this oil as part of the soap.  This technique gave me soap with a subtle cinnamon scent and no scratchy speckles.


Neither essential nor fragrance oils saponify:  they are lipids but they are not triglycerides.  This means that when you use you do not need to include these oils in the formula – they will not be converted to soap.


If you want to use essential oils, a simple and popular combination is spearmint and peppermint essential oils, added at trace in equal amounts – I add 2.3% which is equivalent to a tablespoon of each in 900 grams of oils.  If you like it more tingly, go up to 3%.  Other options are lavender, citrus essential oils, and many others.  Be careful, this can get expensive!


Fragrance oil collecting can also get costly.  If you use fragrance oils, make sure they are suitable for cold process soaps and follow the manufacturer’s recommendations as far as how much to use.


Some essential oils and many fragrance oils can cause troubles when making cold process soap.  Sometimes they cause acceleration of saponification, so your soap will harden very fast, and it is difficult to put it in the mold.  Other fragrance oils and some essential oils can cause your soap to heat up, causing morphological changes, usually just aesthetic issues.  Another effect is the discoloration resulting after using certain fragrance oils, like vanilla for example.



This photograph shows one of my popular scented goat milk soaps: vanilla fragrance oil blended with patchouli essential oil.  The dark areas are the result of discoloration from the vanilla fragrance.


Neither mints nor lavender essential oils cause such discoloration of acceleration problems.  I would recommend starting with one of those since they are also enjoyed by many people.  Lemongrass essential oil also behaves nicely, but it is very strong, so use sparingly!




Coloring soap is not necessary, but some enjoy the creative process, and it makes differentiation easier when you have multiple scents or ingredients.  I introduce color in soap using infusions of alkanet, calendula, annatto, paprika.  I then use the infused oil as part of my total soap oils.  I use indigo crystals (same that are used to color blue jeans) dissolved in the lye water for blues and greens.  Brown can easily be obtained using cocoa powder or vanilla fragrance oil.  Browns, yellows and orange botanical infusions work well in goat milk soaps, but the blues and purples from plants look a little different than when used with water or tea soaps.


Indigo and alkanet in goat milk soap


This is because goat milk soap has a natural yellow/cream color, which makes the indigo blue look green and the purple (alkanet infusions) look more grey.  The picture shows indigo in the mint soap (foreground) and alkanet for the lavender (background) goat milk soaps.  After a 4-6 week cure, these colors will have faded a bit.

I have had good results using activated charcoal and rose clay to increase the color palette in goat milk soaps.  Also, the color introduced by clays or charcoal does not seem to fade after the long cure.




This goat milk soap uses both rose clay and charcoal for color, and it has a sweetly refreshing scent that combines peppermint, eucalyptus, rosemary, orange, patchouli and ylang ylang essential oils.  We call it Shangri-la goat.


I should also mention that there are other coloring options like micas, oxides and many other synthetic colors; so the possibilities are somewhere between vast and endless.  I hope you get to make some soap for the holidays and enjoy the process as much as I do!



Pine Street Products
Handcrafted soaps, lotions, massage oils, and balms. We use herbal infusions, botanical colors and essential oils. Goat milk soap uses milk from goats that have names. 

Pine Street Products (farm division) is a certified California producer. We sell organic fresh citrus, herbs, and other produce at the Altadena Farmer’s Market.

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