Time: 1 hr
Yields: 1000 g soap
This week, I’ve created a soap that shows off the bright colours of the rainbow against a backdrop of white to make the colours really pop out. The technique is very simple, although it does require a bit of preparation.
If you have never made cold-process soap before, I strongly suggest you check out the basic cold process soap tutorial first.
Before starting, please read the safety and precautions post, especially since this tutorial requires the handling of caustic soda!
In addition to your usual soap making equipment, you will need 7 little containers for your colour preparation. The colours I used for the rainbow are micas, which are available from Pure Nature:
- red – Red Pearl mica
- orange – Orange Saffron mica
- yellow – Magic Yellow mica
- green – Green fruit mica
- blue – Blue Lustre mica
- indigo – Dark Violet Purple mica and Magic Violet mica
- violet – Magic Violet mica
Because we are colouring only small amounts of soap, we will be mixing the mica directly with the soap.
Take 7 small containers, which have a volume of at least 100 ml. To each little container add the following amounts of mica:
RED: 1/8 teaspoon of Red Pearl Mica
ORANGE: 1/8 teaspoon of Saffron Orange mica
YELLOW: 1/8 teaspoon of Magic Yellow mica
GREEN: 1/8 teaspoon of Green Fruit mica
BLUE: 1/8 teaspoon of Blue Lustre mica
INDIGO: 1/16 teaspoon of Dark Violet Purple mica and 1/8 teaspoon of Magic Violet mica
VIOLET: 1/8 teaspoon of Magic Violet mica
ONE: To prepare your lye, weigh out the caustic soda in a small container. Then add 280ml water in a small pyrex or other heat proof glass jug. Carefully, add the caustic soda to the water and gently stir until all the caustic soda has dissolved. Stir in two teaspoons of sodium lactate to harden the soap quicker and shorten the curing time.
TWO: Weigh out and add the coconut oil to a large Pyrex jug. I’m using a 1.5L Pyrex jug here. Place the jug in the microwave and heat until the coconut oil has melted.
THREE: Add the remaining oils and give it a quick stir. Set aside.
FOUR: When the lye has cooled to room temperature, i.e. the outside of the jug feels cool to touch, you can carefully pour the lye to the oils. Make sure you are wearing protective gear (goggles and gloves) and avoid making any splashes.
FIVE: Using only a whisk, stir briskly until the mixture has emulsified (i.e. very thin trace). You know when it has emulsified, when there are no more streaks of oil and the mixture does not separate if you leave it to stand for a while.
SIX: Add the essential oils and give it another quick stir. If you decide to use a different blend of essential oils or fragrances, make sure that these do cause the soap to accelerate, in other words cause the soap to thicken or seize.
SEVEN: To each of the seven pots, add approximately 60 ml of soap.
EIGHT: Pour about 2/3 of the what is left of the white soap into the soap mold. Tap the mold gently on the bench top to even out the surface.
NINE: If you haven’t already, stir each of the seven pots until the colours have been mixed well throughout the soap.
Then, starting with VIOLET, pour a line of soap along the length of the mold, about 1/3 away from the edge.
Next, pour INDIGO into the same line of soap you just poured. You want to layer the colours into each other. Gravity will make the colours spread out.
Keep pouring the colours into the line of the previous one in this order: BLUE, GREEN, YELLOW, ORANGE, and RED.
Don’t worry if you have colour left in the containers, you will be using that to create the top.
TEN: Carefully pour the remainder of the white soap into the mold, making sure you cover all the coloured soap.
ELEVEN: To create the top, just drip whatever coloured soap you have left randomly over the surface. At the end, spritz the surface with 99% isopropyl alcohol to prevent soap ash forming, which would otherwise dull the colours.
TWELVE: Leave the soap to cure for a few days in the mold, before removing. Then leave it to cure for another few days, before cutting it into bars. The bars of soap will need at least another 4 weeks to finish curing.
- 500 g olive oil
- 250 g coconut oil
- 200 g sunflower oil
- 50 g castor oil
- 137 g caustic soda
- 280 ml water
- 2 teaspoons sodium lactate
- Red Pearl mica
- Orange Saffron mica
- Magic Yellow mica
- Green Fruit mica
- Blue Lustre mica
- Dark Violet Purple mica
- Magic Violet mica
- 30 ml pink grapefruit essential oil
- 20 ml lemon essential oil
- 99% isopropyl alcohol
- Colour preparation: Take 7 small containers and to each add the following amounts of mica:
- RED – 1/8 teaspoon Red Pearl mica
- ORANGE – 1/8 teaspoon Orange Saffron mica
- YELLOW – 1/8 teaspoon Magic Yellow mica
- GREEN – 1/8 teaspoon Green Fruit mica
- BLUE – 1/8 teaspoon Blue Lustre mica
- INDIGO – 1/16 teaspoon each of Dark Purple Violet mica and Magic Violet mica
- VIOLET – 1/8 teaspoon Magic Violet mica
- Prepare your lye: carefully add the caustic soda to the water and stir gently until all the caustic soda has dissolved. Add two teaspoon of sodium lactate. Set aside to cool.
- In a large jug (I use a 1.5 L Pyrex jug), weigh out and add your coconut oil and place it in the microwave for 2 minutes to melt.
- Weigh out and add the other oils, stir briefly and set aside.
- Once your lye has cooled down to room temperature, add the lye to your oils and stir with a whisk until the mixture has emulsified. Be careful not to over-whisk, because you don’t want the mixture to thicken.
- Add your essential oils and give it another quick stir.
- Next, pour approximately 60 m of soap into each of the 7 containers.
- Then, pour about 2/3 of what is left into the soap mold.
- For the rainbow:
- stir each container until the colour is well mixed into the soap
- start with VIOLET, pour a line of soap about 1/3 from the edge along the whole length of the mold
- pour the next colour, INDIGO, into the same line of soap you poured previously
- keep pouring the colours into the previous line you just poured in this order: BLUE, GREEN, YELLOW, ORANGE, and RED.
- Carefully pour the remainder of the white soap to cover the coloured soap.
- To create the top, drip what is left of the coloured soap over the surface. Spritz the surface with 99% isopropyl alcohol to prevent soap ash forming.
- Leave the soap in the mold for a few days to harden. Once the soap is firm enough, remove from the mold and let it cure for another couple of days before cutting into bars. The bars will need at least another 4 weeks to finish curing.