Beware: After 5 weeks of cure time I noticed the two bottom layers starting to fade. I’m working on an updated tutorial for you, in the meantime I hope you find this information helpful nonetheless.
Indigo is an interesting natural colorant to work with in cold process soap. As with most natural colorants you never quite know what you’re going to get. The color results can vary greatly from greenish to grayish blue depending on the type of indigo used and how it’s incorporated into the soap.
I kept putting off this project, because to be honest indigo intimidated me a little. There seemed to be a whole bunch of issues folks kept running into. Starting with getting a color they didn’t like (ugly gray) to getting no color at all and ending with colored lather and blue wash cloths.
In this tutorial I use a very easy form of oil infusion, which I think worked really well. I also tried using the indigo powder directly in the hot lye solution in my test runs, but didn’t find the color result to be very pleasing with this particular indigo powder. Read on to see first what I did in my test runs, and then to see the full tutorial using the oil infusion method.
Adding Indigo Powder to Lye Solution
For this example I used 3/4 tsp of indigo powder from Nurture Soap Supplies for 1 lb of soap. I could have used more for a stronger color.
- Add indigo powder to the lye solution as soon as the lye is completely dissolved and while the solution is still hot
- Make sure to incorporate the indigo as best you can
- When the indigo lye solution has cooled, strain it through a fine mesh sifter lined with a coffee filter
- You will have to press or squeeze the lye solution through the coffee filter using a spoon
- Add the lye solution to the oils, the indigo will sink to the bottom of the pot and that’s fine
- Proceed as you normally would by using your stick blender to achieve trace
- Make sure to gel your soap to get the best result
- Note: This technique only works for single color soaps
Tips for Using Indigo in Cold Process Soap
- Always, always test your indigo in a small batch before making bigger batches. Depending on the supplier the result can vary greatly. Amy Warden from Great Cakes Soapworks has tested a multitude of different indigo materials, suppliers and incorporating methods in this great article. It’s a must read.
- Use the whitest soap recipe possible. Usually you’re able to tell from looking at your oils or butters how they will color the soap batter. Good choices for a white batter are: coconut, canola, babassu, palm and olive (not pomace) oil, as well as tallow and shea butter (refined). If your oils have a greenish or yellowish tint to them, you will end up with an ugly brown.
- Gel your soap
How to Pour an Ombre Soap Using Only One Pot
The ombre layer technique that most are familiar with is the one where you split your batch into different pots, color each one, stick blend to thick trace and then plop it into the mold. But here’s the thing: Dishes (Ahhh!!!).
I wanted to try a technique that didn’t involve all the hassle of having to clean a gazillion pots and would still give me a beautiful ombre layer effect.
Here are some pointers on how to do that:
- The key is to never let your main batter set up, this requires constant stirring
- Try to pour each layer at thin to medium trace and then let it set up in the mold while you stir the rest of the batter
- Check each layer before pouring the next one with a spoon to make sure it’s thick enough to hold the next layer. Here’s what you’re looking for: if you press down on the layer with the back of your spoon it should give you some resistance (if you sink right in, it’s not ready yet), when you pull the spoon away the batter should leave a mount that remains and doesn’t sink right back in
- Tap your mold thoroughly. Through all that stirring you will incorporate lots of tiny air bubbles. Make sure you get them out ideally after you pour each layer. You can see that I could’ve done a better job with this (lots of teeny specks)
Are you pumped to start with this soap? Great, me too!
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- Two heat resistant medium sized containers (not glass) and one small cup
- Stick blender
- Accurate kitchen scale
- Gloves and goggles (for protection)
- Crafter’s Choice silicone loaf mold
- Spoon (medium, not aluminum)
- Chop stick
Recipe (makes 7 -8 regular sized bars or around 42 oz / 1180 g of soap):
This recipe uses a 40 % lye concentration (for easier unmolding and less soda ash) and is superfatted at 5%.
- Distilled Water: 6.3 oz / 118 g
- Lye: 4.2 oz / 118 g
- Canola Oil (38%): 11.5 oz / 326 g
- Coconut Oil (30%): 9 oz / 255 g
- Shea Butter refined (27%): 8 oz / 227 g
- Castor Oil (5%): 1.5 oz / 43 g
- Indigo Powder (Nurture Soap Supplies): 1 tsp
- Lavender Essential Oil: 13 g
- Litsea Cubeba (May Chang) Essential Oil: 13 g
- Peppermint Essential Oil: 6 g
- Gear up for safety: gloves, goggles, no pets or kids around
- Prepare your lye solution by carefully adding the lye to the water (never the other way around!)
- Stir until the lye is dissolved and set aside
- Melt coconut oil and shea butter in a double boiler on low heat or in the microwave on 30 second bursts
- Add canola and castor oil to melted coconut oil and shea butter
- Carefully measure essential oils and add them to the base oils
- In a small cup prepare indigo powder by mixing 1 tsp of indigo powder with 1 Tbsp of canola oil, mix thoroughly until you see no more clumps
- Make sure to have whisk, pipette and spoon ready
- Add lye solution to base oils by pouring down the shaft of your stick blender
- Stick blend until you reach medium trace (thin pudding consistency with trailing on surface of the batter)
- Pour 1/4 of the uncolored batter into the mold by eyeballing it or by weighing the empty mold, then taring the scale and weighing out 10.5 oz / 395 g of the batter
- Tap down your mold
- To the remaining main batter add 2 ml of indigo oil infusion and whisk consistently until you’re ready to pour again (this will keep the batter fluid)
- Check the first layer with the back of your spoon to make sure it has set up enough to hold another layer (you should feel a good amount of resistance with your spoon and it should leave a mount when pulled away)
- Carefully pour the second layer by either pouring the batter over a spatula close to the first layer to break the impact or by carefully scooping the batter in with a spoon
- Tap down your mold
- To remaining batter add another 2 ml of indigo infusion and whisk until you’re ready to pour
- Check the 2nd layer for thick consistency
- Pour the 3rd layer
- Tap down your mold
- Add another 2 ml of indigo infusion to the remaining batter and whisk continuously
- Check 3rd layer to see if it has set up enough
- Pour the 4th and last layer
- Once all the batter is in the mold, give a thorough tap
- Using the pipette sparingly sprinkle some of the indigo infusion evenly across the top of the soap
- With a chop stick swirl the top to create a pretty design
- Cover mold in heavy blanket or place in the oven on 170 degrees F for 30 min, then shut the oven off and leave over night
- After 36 hours unmold and cut into bars
- Cure for 4 -6 weeks
Looking for more indigo soap tutorials?
- Blue Marble Soap (Humblebee & Me)
- Snow Soap with Indigo & Clay (Modern Soapmaking)
- Indigo Spoon Plop Soap (Sop Queen)
Until next time. Happy Tinkering!