DIY: Homemade Castile Shampoo Bars with Tea Tree and Peppermint

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A couple of months ago I started making soap. After tons of reading and quite a bit of confusion, I finally figured out the basics and made my first batch of ‘lye soap’, just like Great-Grandma used to make. It turned out great! I then decided to make some shampoo bars.

handmade soap - castile shampoo bars

This is the lye I used. I don’t say ‘lye’ or even NaOH. I bought it at Home Hardware. Thankfully, there was an older (70+) man working at the store that day and he knew just what I needed. It was about $5.

making homemade soap / shampoo bars

FYI: Lye (strong alkaline) is necessary to make soap (process is nearly 3000 years old). However, after the chemical reaction between the fat and the lye (saponification) the lye (strong alkaline)is gone and what you have left is SOAP! Yes!

You WON’T be washing in LYE … I promise!

100% natural soap!

Lye and Water + Fat = Soap

Different types of fats can be used in the soap making process. Lard, Vegetable shortening, Vegetable Oil, Coconut oil, Castor Oil, Jojoba oil, Olive Oil … The list is endless.

After looking at many recipes (use Google), I decided I wanted my shampoo bars to consist of Olive Oil, Coconut Oil (good for dry hair) and Castor Oil (lots of suds)!

I decided for a 2:1:1 ratio for the oils. You can make up any combination you want!

My recipe:

8 oz Olive Oil
4 oz Coconut Oil
4 oz Castor Oil

I carefully measured out these ingredients using a scale and put them in a small pot suitable for heating on the stove.

I then figured out how much lye and water to use, by using this soap making calculator. I find it easier to measure out your oils and then calculate exactly how much lye & water to use.

After putting the above amounts into the calculator, it is recommended that I use (based on 6% excess fats – good for shampoo):

2.19 oz lye
4 – 6 oz water

making homemade soap / shampoo bars

Basic Soap-making Instructions:

* While wearing safety goggles and neoprene gloves, combine solid lye and liquid, stir well. Set aside and allow to cool (100° F to 125° F). This is best done outside while you are standing upwind.

making homemade soap / shampoo bars

* Combine oils and heat gently. Once the fats and oils are melted allow the temperature to drop to 100° F to 125° F.

* Combine lye solution and melted oils. Be careful not to splash while combining the mixtures. Stir until the mixture traces. If tracing takes more than 15 minutes, which it often does, stir for the first 15 minutes, then stir for 5 minutes at 15 minute intervals. Tracing looks like a slightly thickened custard, not instant pudding but a cooked custard. It will support a drop, or your stir marks for several seconds. Once tracing occurs…

making homemade soap / shampoo bars

NOTE: I use a stick blender and this recipe reached trace in under 5 minutes.

What is trace?: Trace is when the soap mixture reaches a consistency similar to pudding. When you lift your spoon/blender and dribble the soap on itself, the trail of soap leaves a trace of itself before blending back in. Definition of trace.

making homemade soap / shampoo bars

* Add Essential Oils for scent. In this case I added 1 tsp of Tea tree Oil and 1 tsp of Peppermint oil.

* Pour raw soap into your prepared molds. After a few days the soap can be turned out of the mold. If the soap is very soft, allow it to cure for a few days to firm the outside.

NOTE: I used a clean milk carton (waxed paper type not plastic bottle). 1 litre size in Canada or 32 oz in the USA.

* Cut soap into bars and set the bars out to cure and dry. This will allow the bar to firm and finish saponification. Place the bars on something that will allow them to breathe.

Read this article on Soap Making Safety, BEFORE you get started.

handmade soap - castile shampoo bars

This shampoo turned out wonderful. Luxurious lather and it leaves my hair soft and silky. NO tangles. I smells nice too. In addition we use it as regular body soap too. It’s nice not to have all of those plastic bottles in the shower.


MK xo


Jo · July 23, 2012 at 6:20 pm

Love it!

Kenneth · July 24, 2012 at 12:48 am

Very interesting mixture of oils.

Shawna Moroz · September 8, 2012 at 6:35 pm

where do you get your coconut and castor oils?

    MommyKnows · September 10, 2012 at 6:19 pm

    @Shawna Moroz, I see from your email address that you are in Canada. I picked up my coconut oil at Homesense in the food section near the ‘health foods’ like agave syrup and gluten free cake mixes.

    The castor oil is from Shoppers Drug Mart. They sell 4oz bottles in the laxative aisle (I think it was laxatives).

    Thanks for stopping by and of course for taking the time to comment!

Katie · November 7, 2012 at 2:33 pm

I made this a month ago and it’s exactly what I was looking for in a shampoo bar. I have fine, slightly oily hair and this cleans my hair great.

I did steep a bunch of herbs (that are good for hair) in the water before making it. So my bars look a dark brown/green. I’m not sure how much herbs will add to the health of the soap but it was a fun addition. I added about an ounce of rosemary essential oil as well.

Thanks for posting!

Rebekah · February 24, 2013 at 8:31 pm

How many bars of soap did this recipe make (based on the size of bars that you have shown in the picture)?

Cristina · June 6, 2013 at 9:54 am

I had tried a few different recipes for shampoo, but have to say that this is my favorite. I followed your recipe. It turned out great and I have been using it for about 2 weeks. The only thing is that now I am on the hunt for a conditioner.

Thank you so much for posting your recipe!! My hair loves it!!

Michele · September 8, 2013 at 5:54 pm

I love this recipe! I have been using for about 4 months now for my shampoo & soap. I just started making my own cleaning products and I use this recipe for my base castile soap in those recipes as well. Works great!! Thanks for posting it!

Trillian · November 1, 2013 at 3:53 pm

Hi! Did my solid shampoo today inspired from your recipe but with some differences: i added a 5% of flaxseed oil and instead of the water i used a chamomile infusion.
I have a question: how long after you do it you can use it?
Because i red that you may need to make the soap rest for few weeks, for example when making castile soap.
Thanks and sorry for my english ( am from italy).

Amanda · November 8, 2013 at 4:04 pm

How long does it take to cure?

Teresa · June 2, 2014 at 6:24 pm

This is the simplest shampoo bar recipe I have ever found. Most call for so many different kinds of strange oils. I need to pick up some castor oil, and I’m going to give this one a try. Thanks!

Gabrielle · June 12, 2014 at 10:37 pm

Would you recommend this for someone who gets oily hair easily? Or what oils would you recommend? :) Thanks

Flor · December 10, 2014 at 4:45 pm

I have the same question as Gabrielle. Does it work on oily hair?

Janice · January 30, 2015 at 8:11 pm

Can you sub Palm oil for the castor oil?

Celeste · September 17, 2015 at 9:13 pm

I’m still afraid of lye. I wish there were a more natural alternative.

Matthew Javinett · April 18, 2016 at 4:08 pm

How much does this recipe make? I use milk cartons as well and would like to know how many bars it would make? Can the recipe be doubled?

PiaPollo · September 16, 2016 at 10:08 am

May I ask, What can I use instead if castor oil?

Tammy · April 8, 2017 at 4:49 pm

Please add to this the temp. to let lye cool down too so no one gets hurt.

Scottie · December 29, 2019 at 6:16 pm

I started looking for a shampoo recipe and came across yours. I’ve used one my husband buys but it leaves my hair really dry… the oils help with conditioning at all?

Brittany · June 8, 2020 at 12:54 pm

How much water did you use?

Brittany · June 12, 2020 at 3:32 pm

How much water did you use for this shampoo bar

Ideas For Handmade Gifts For Christmas | Money Thrifty · November 26, 2013 at 6:59 pm

[…] Make up a batch of shampoo bars for yourself and add a few to gift baskets for friends. Learn how to make your own HERE. […]

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