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Join Jo: Using Natural Colorants in Soap with Your Lye Solution

guest contributors soap science and info
soap bar colored with manjistha

One of my favorite ways to use botanicals in soap is to make soap with the plant colorant directly in the lye solution!

Madder (Rubia tinctorum), indigo (Indigofera Tinctoria), and manjistha (Rubia Cordifolia) are three natural colorants that can be used straight into the lye solution to bring out their best color.

Madder and manjistha will give a gorgeous pink, depending on the amount you use.  The color can range from a dusky pale pink right though to a dark pink, but be careful using too much, it can give pink bubbles and be hard to remove from white cloths and baths!

Indigo will give a color range from a beautiful robin’s egg blue right through to navy blue and almost black.  Again, be aware that you may have colored lather and the color may be hard to remove from white cloths and baths.

For your first time using any natural colorant in your lye solution, don’t worry about straining it, just try using the colorant and see what the results are.  Next time you use the natural colorant, you will know the color to expect and can adjust the amount used. If you don’t want specks in your finished soap, you will know if you need to strain the lye solution.

Use a soap recipe you are comfortable with, so the only new technique will be using the colorant in your lye solution. Remember to use the whitest oils you can so that you can see the gorgeous color at the end, and remember to gel to get the full impact!

I use 2.5 tablespoons of madder root for a 5 lb soap batch (roughly ½ tablespoon per pound of oils) – for a dusky pastel pink. I use the same amount of manjistha for a brighter pink and I use ½ teaspoon of indigo powder for a denim blue. If you would like a brighter pink you can use 1 tablespoon per pound of oils for the madder and manjistha.

Using Natural Colorants in Soap with Your Lye Solution

These photos are of manjistha being used, however, I follow the same procedure for madder root and indigo or any of the other colorants that I use in lye solution.

Measure the amount of colorant you need into a cup. Make your lye solution in the way you normally do, following all the usual safety precautions.

Immediately after you have added the lye to your water and it has dissolved, add your natural colorant.  Pour the dry natural colorant straight in your lye solution, and stir it around.  You should see something similar to this:

 Manjistha added to lye solution

It will look like there are bits in the lye water, and it will look really dark, almost a maroon color.  Don’t worry, it won't stay this color, but this is completely normal!

If you are like me, you like to know what is going on. I keep a dish with cold water next to my lye water and I place the spoon that has been stirring the lye into the dish – to check the color! It’s a great way to see the magic of plant colorants at their best.

 The lye solution mixing spoon in a little water

Look at all those specks and look at the gorgeous pink!

This pink color around the edges is very close to the color that the soap will be when wet in the mold. I like to strain my lye solution, so I don’t have those specks. However, you don’t have to do this step.

I am including how I strain for those soapmakers that would like to see how someone else does it.  I consider straining the lye solution to be an advanced technique, and encourage you to give this a try without straining first. (Be careful, your lye solution is caustic and can splash! Suit up!)

 Filtering the manjistha & lye solution through cheesecloth

As you can see, my filter system is really simple: cheesecloth folded 4 times and placed into a sieve (dedicated to soaping). The sieve is resting on the top of my bucket that already has my base oils in it ready to go.

You will need to use your spoon to encourage all the liquid to pass through the cheesecloth - it does take some time to filter through.  Your cloth will have a gorgeous pink to it forever. As you can see, I also use it for woad and indigo as you can spy the blue spots on left of picture.  When I have finished with the cloth, I rinse it, wash it, and hang it up to dry ready to go for the next time.  Its quite pretty to look at, too!

Once the lye filters through to the oils, it will settle at the bottom of the bucket and you will see this really cool effect!

 After adding the lye solution to your base oils, it'll sink to the bottom!

That is the lye and madder waiting to be stick blended!  I love to see the oil on top and the colorant at the bottom.

Now you can make your soap just how you normally do.  Stick blend until you get to the amount of trace you like to use.  Here is how the manjistha looks once you get to emulsification stage.  I love that bright color!

 After blending the manjistha lye solution and oils, it turns a beautiful pink!

Pour the soap batter straight into your mold and decorate as you would like.  In the following photo, you can see white lines of zinc oxide to give you a reference of the color when wet and fresh in the soap batter.

 The raw manjistha colored soap in the mold

You can expect changes to occur whilst the soap is gelling. When you unmold the soap, the color will be quite a bit paler than it was in the mold.

 Pink manjistha soap in the mold with a decorated top for contrast

The following photo shows a comparison of French Pink Clay on the bottom, Manjistha root in the middle and Madder root on the top. All three were used directly into the lye water.

 From Top to Bottom: French Pink Clay, Manjistha, and Madder Root

Other botanicals to try in your lye solution:

  • Black walnut hull - brown with pink tone and less speckled than at trace
  • Calendula petals  - bright yellow, pastel if not gelled
  • Charcoal powder – add less than normal (less specks than if added at trace)
  • Cinnamon powder - dark brown
  • Cocoa powder - darker brown than if added at trace
  • Paprika powder - orange with pink tones
  • Rosehip powder – chocolate brown
  • Safflower powder - burnt orange color
  • Spirulina - khaki green (has fewer specks if added to lye)

Clays to try in your lye solution:

  • Rose Clay – darker pink than if added at trace
  • Pink Kaolin Clay – pink with orange tone

Fruits and Veggies to try in your lye solution:

  • Tomato paste  - orange (decrease water amount by the amount of tomato paste added)
  • Pumpkin - orange (decrease water amount by the amount of pumpkin puree added)
  • Carrot - orange (decrease water amount by the amount of carrot juice/pulp added)

 A range of naturally colored soaps made by Jo Haslauer

I really hope you have enjoyed the series on using natural colorants in soap making.  I love using natural colorants, and really enjoy seeing the changes that occur - I look forward to seeing your beautiful creations using some of these methods!

Did you miss the first post in the Coloring Soap Naturally series? You can find it here!

Did you miss the second post in the Coloring Soap Naturally series about how to make infusions? Find that one right over here!

How about the third post in the Coloring Soap Naturally series about using plant infusions in your soapmaking? Yup, you guessed it - it can be found here.

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