Make Your Own Shampoo and Test How It Performs!
AbstractDo you like your hair shiny and beautiful? The key to keeping your hair nice and clean is to use a good shampoo. But with so many different products in the store, how do you know which one works best for you? In this science project, you will put a variety of shampoos to the test, including your own self-made organic shampoo recipes. Do you think these will perform better than a store-bought product?
Make your own shampoos and do some quantitative testing to compare their performance to a store-bought product.
Do you care about your hair and how it looks? Most likely, yes. After all, your hair is visible to everyone and you don't want it to appear all greasy and messy! As it frames your face, the hair is probably one part of the body that many people care most about. Just think of all the hair care products that you can buy: shampoo, conditioner, spray, mousse, or wax, just to name a few. Shampoo is by far the most common product used for hair treatment across all hair colors and lengths. Some people use "organic" shampoos, or even make their own recipes, because they do not like the synthetic chemical products in the shampoos in the store. Although there exist many different shampoo recipes and products in the stores as shown in Figure 1, they all have the same purpose: to clean your hair and scalp from dirt or grease. Your hair tends to get greasy because it accumulates an oily substance, also called sebum, that is made by your body to moisturize your scalp and protect your hair from drying out. If you have too much of it in your hair, it looks oily. How can shampoos remove all this build-up of grease?
Figure 1. There are many different types of shampoo— how do you know which one works best?
To find out, we will take a closer look at the shampoo ingredients, or its recipe, also called formulation. Besides water, surfactants are the main ingredients in shampoos. They have names such as sodium lauryl sulfate, sodium laureth sulfate or cocamidopropyl betaine. Surfactants are unique chemicals as their chemical structure has a hydrophobic (water-repelling) tail and a hydrophilic (water-loving) head, as shown in Figure 2. This property allows them to react with both water and oil, which normally doesn't mix with water.
Figure 2. The molecular structure of a surfactant contains a hydrophobic "tail" and a hydrophilic "head."
The surfactants in shampoo account for its cleaning power. When washing your hair, the part of the surfactant that is compatible with oil (hydrophobic tail) sticks to the greasy and oily materials in your hair, whereas the water-soluble part, the hydrophilic head, aligns with the water. If many surfactant molecules do this, they form a micelle structure, which traps the grease and oil in its middle, as shown in Figure 3. This way, the oil that is trapped in water with surfactants can easily be washed away, while water without surfactants fails to remove the grease from your hair.
Figure 3. Schematic view of a micelle structure (not to scale). In a micelle, the hydrophobic tails of surfactant molecules stick to the oily particles, whereas the hydrophilic heads align with the surrounding water.
Although its cleaning power is probably the most important criteria for a good shampoo, there are many other aspects that decide the quality of a shampoo. In fact, a shampoo needs to meet many requirements to be accepted by customers like yourself. This is why, besides surfactants, there are also so-called additives in each shampoo that optimize its look, feel, or performance, such as additional foam builders, thickeners, conditioning agents, or preservatives. For example, the ability to create lots of foam is important because people associate more foam with more cleaning power. Although this is not necessarily true, a shampoo sells much better if it makes more foam. Therefore, additional (synthetic) surfactants are used as foam builders that have a strong capability to produce foam. Just think about what you love about your favorite shampoo! You probably would not like it if it would not meet all the criteria below (and probably some more):
- It removes the dirt and grease from your hair
- It makes a good amount of foam so it feels nice and you can spread it easily through your hair
- It does not stick to your hair and can easily be rinsed
- It makes your hair shiny and soft
- It smells nice
- It does not irritate your scalp or your hands
This is why the cosmetics industry and world of beauty products needs scientists! Scientists constantly research new shampoo formulations and developed specific quantitative tests to evaluate each of these properties for every new product they create. The combination of these specific tests allows them to compare different shampoo recipes based on quantitative data to find the one formula that performs best overall. For example, they can find out which ingredients help to remove grease most efficiently or make the best foam.
In this science project, you will create your own shampoos using two different recipes based on organic ingredients. Many people prefer "organic" or natural beauty products as they want to avoid synthetic (or man-made) chemicals that might damage their skin or could potentially be harmful. The most common organic replacement of synthetic surfactants are soaps based on olive or coconut oil. Castile soap, a surfactant made from olive oil, is one example that you will use in this project. Other natural shampoo formulations try to avoid surfactants entirely as they can throw off the pH balance of your scalp and might irritate your hair and skin. You will also prepare one of these shampoo recipes without surfactants which is based just on coconut milk. Do you think these organic shampoos are as good as a store-bought product? Start the shampoo testing and find out!
Terms and Concepts
- Why do people use shampoo?
- What ingredients are in shampoo? Can you find out the purpose of each of them?
- Which properties are most important for a shampoo and how would you test these? Which tests do commercial companies use?
- What are the reasons why some people use their own organic shampoo formula? Do you think these products can perform as well as synthetic shampoo formula?
- How Products are Made. (n.d.). Shampoo. Madehow.com. Retrieved March 10, 2017.
- Schwarcz, J. (1998). Secrets of Shampoo. Special to The Washington Post. Retrieved March 10, 2017.
- Casse, L. (2016). Types of surfactants in your shampoo. hairmomentum.com. Retrieved March 10, 2017.
- Manimaran V. (n.d.) Formulation & Evalutation of Shampoo. Lecture (Unit V), Department of Pharmaceutics, SRM College of Pharmacy. Retrieved March 10, 2017.
- Kumar A., Mali R. R.. (2010). Evaluation of Prepared Shampoo Formulations and to Compare Formulated Shampoo With Marketed Shampoos. International Journal of Pharmaceutical Sciences Review and Research Volume 3, Issue 1, p 120–126. Retrieved March 10 2017.
Materials and EquipmentYou will need these items to make your own organic shampoo:
- Containers or bottles for shampoo, 16 oz (2)
- Measuring cup
- Tablespoons (at least one)
- Teaspoons (at least one)
- Bowls (2)
- Full fat coconut milk (14 fl oz can)
- Honey (2 tablespoons)
- Jojoba oil (2 teaspoons)
- Olive oil
- Apple cider vinegar (2 tablespoons)
- Essential oil (for example, lavender or lemon) (1 teaspoon)
- Cup, 4–5 oz
- Fresh herbs (such as thyme, lavender, rosemary, chamomile) or a herbal teabag
- Tap water
- Oven or microwave to heat up water
- Castile soap (2 oz)
- Shampoo of your choice (store-bought)
- Mason jars with lid, 8 oz (one for each shampoo you test)
- Mason jar with lid, 16 oz (1)
- Wool yarn, should be natural color and 100% wool; available from Amazon.com
- Digital scale with 0.1 g increments; a digital scale that would be suitable is the Fast Weigh MS-500-BLK Digital Pocket Scale, available from Amazon.com
- Coconut oil
- Acetone (about 900 mL); available at your local hardware store.
- Safety goggles
- Latex or nitrile gloves
- Stopwatch or timer
- Aluminum foil
- Heat-resistant bowl
- Kitchen thermometer
- Paper towels
- Heat-resistant plates (3)
- pH test strips; available from Amazon.com
- 250 mL measuring cylinder; available from Amazon.com
- Test tubes; available from Amazon.com. Alternatively, 2 oz mini cups with lids can be used.
- Indian ink; available from Amazon.com
- Medicine dropper or pipette
- Permanent marker
- Lab notebook
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Making the Shampoos
You will start by preparing two different shampoo formulations as shown in Table 1.
|Recipe 1: Coconut milk shampoo||Recipe 2: Castile soap herbal shampoo|
|Coconut milk (full-fat)||1 can||Herbal-infused water||4–5 oz|
|Honey||2 tablespoons||Castile soap||2 oz|
|Jojoba oil||1 teaspoon||Jojoba oil||0.5 teaspoons|
|Olive oil||1 teaspoon||Essential oil aroma||1 teaspoon|
|Apple cider vinegar||2 tablespoons|
|Essential oil aroma||1 teaspoon|
Click through the slideshow for step-by-step instructions for making the shampoo.
Testing the Cleaning Power
The most important criteria of a shampoo is how efficiently it removes dirt and grease from your hair. In this test, you will measure how much grease is removed from dirty wool (which simulates hair) in one washing cycle.
Before you start, copy Table 2 in your lab notebook. It will help you record the data.
|Grease removal from dirty sample|
|Mass measurements, expressed in grams [g]|
|Wool soaked |
|Wool dried |
|Coconut milk shampoo||Trial 1|
|Castile soap herbal shampoo||Trial 1|
|Store-bought shampoo||Trial 1|
Click through the slideshow for step-by-step instructions for testing the shampoo cleaning.
Testing the Skin and Hair Compatibility
In this test, you will test how acidic or basic your shampoo is, which you can find out by measuring its pH. A pH > 7 means a solution is basic, whereas a pH < 7 means that a solution is acidic. A solution is neutral if its pH is equal to 7. Your skin and hair have a pH that is in the neutral range or slightly acidic (5.5–6). Their pH balance can easily be affected by products that are very acidic or basic. Therefore, this pH test will evaluate if the shampoo is skin- and hair-friendly, or if it has the potential to irritate your scalp and damage your hair.
Before you start, copy Table 3 in your lab notebook. It will help you record the data.
|pH of the 10% shampoo solution|
|Coconut milk shampoo|
|Castile soap herbal shampoo|
Click through the slideshow for step-by-step instructions for testing compatibility.
Testing the Foaming Behavior
Most people associate a great volume of foam with a "better" shampoo product (although scientific tests have shown that foam does not have a great influence on a shampoo's cleaning power). Therefore, the foaming behavior is an important characteristic for customer acceptance. In this test, you will evaluate the shampoo's foam volume and stability.
Before you start, copy Table 4 in your lab notebook. It will help you record the data.
|Foam volume [in mL] and stability of the 10% shampoo solution|
|Trial 1||Trial 2||Trial 3|
|Foam level [mL]||0 min||1 min||2 min||3 min||4 min||0 min||1 min||2 min||3 min||4 min||0 min||1 min||2 min||3 min||4 min|
|Coconut milk shampoo||Top|
|Castile soap herbal shampoo||Top|
Click through the slideshow for step-by-step instructions for testing the foaming of the shampoo.
Testing the Dirt Dispersion
A good shampoo should make it easy to rinse dirt from your hair off. However, if the dirt gets trapped in the foam of the shampoo, it is likely to redeposit on your hair and will stay there. In this test, you will assess if the shampoo concentrates dirt in the foam or water phase (which makes it easier to rinse it off). In contrast to the previous tests, which were quantitative tests, this will be a qualitative test in which you will only observe but not measure the quality of each shampoo.
Before you start, copy Table 5 in your lab notebook. It will help you record the data.
|Amount of ink (color intensity) in the foam|
|Trial 1||Trial 2||Trial 3|
|Coconut milk shampoo|
|Castile soap herbal shampoo|
Click through the slideshow for step-by-step instructions for testing the dirt dispersion of the shampoo.
Analyzing Your Results
You have collected a lot of data! Now it is time to bring it all together and assess each test separately, as well as all tests combined.
- Assessing cleaning power from your results in data table 2.
- Start with calculating how much grease, or artificial sebum, (in grams), was taken up by each of the wool pieces. To do this, subtract the starting mass of the wool from the wool mass soaked with grease (after the acetone evaporation). Write down your results in your data table.
- Next, calculate how much grease was removed during the washing cycle for each trial. Subtract the final mass of the wool piece after washing and drying from the wool mass of the wool soaked with grease. Record the results in your data table. Note: If your result is negative, that means that instead of removing grease, the wool gained mass during the washing. If this happened, do you think this could be extra grease? Did the wool piece still feel very greasy after washing? Where could the extra grease have come from?
- Calculate the average wool masses from each step from all your three trials. Write down the averages in your data table.
- Finally, you can calculate the cleaning power of your shampoo as percentage. To do this, divide the amount of grease removed by the amount of grease taken up by the wool and then multiply by 100. Note: Again, if your percentage is negative, that means that your wool mass increased instead of decreased. If this was the case, think about what this extra mass could be and where it could have come from (see questions in step b.).
- Make a bar graph with the shampoo name on the horizontal x-axis and the cleaning power in percentage on the vertical y-axis.
- Looking at your cleaning power results, which shampoo is most efficient in removing grease from your hair? Was there a shampoo that had very low to no cleaning power? Can you think of reasons why a wool piece could gain mass during washing? Can you explain the differences in cleaning power looking at the ingredient list of each shampoo? Look back to the Introduction to find out which shampoo ingredients are most important for removing grease. Do you find this type of ingredient in all the shampoo recipes?
- Assessing skin-and-hair-compatibility from your results in data table 3.
- Make a bar graph that shows the shampoo name or recipe on the x-axis and the average pH value on the y-axis.
- Do all the shampoos have the same pH value? If not, which ingredients do you think make a difference? Do you think your shampoos are skin- and hair-friendly? Why or why not?
- Assessing foam volume and stability from your results in data table 4.
- Calculate the foam volume for each shampoo and trial by subtracting the mL readings of the bottom from the top readings for each time point. Record the calculated volumes in your data table.
- Determine the average foam volumes.
- Make a bar graph that shows the initial foam volume after shaking (at 0 minutes) for each shampoo, with the shampoo name on the x-axis and average foam volume on the y-axis.
- Then, make another graph that shows foam stability and how the foam volume changes over time. This time, use a line graph and plot the time point (0, 1, 2, 3, 4 minutes) on the x-axis and the average foam volume for each time point on the y-axis. You can make an individual graph for each shampoo recipe or show all shampoos in one graph using different colors for each line.
- Which shampoo made the most foam? How stable was the foam? Was there a shampoo that did not make any foam? Can you correlate the foaming behavior with a specific shampoo ingredient, when looking at the differences in the shampoo recipes?
- Assessing dirt dispersion from your results in data table 5.
- You can use your data table directly to show your results on the display board.
- Did all shampoos perform the same? Which shampoo do you think will remove dirt best from your hair?
- Can you draw a final conclusion from your study about which shampoo performs best? What did you learn from each test about the shampoos? Do you think you need more tests to confirm your results? What do your combined results mean for your shampoo recipes? What ingredients did you find to be most important in your shampoos?
Ask an Expert
- Are you curious about how other shampoos perform? What about specialty shampoos such as baby products or dandruff shampoos? Do they have different qualities? Find out by repeating the tests in this experiment with these products and compare the results to regular shampoo. You can always include more shampoos in your testing, including other self-made recipes that you want to try!
- The cleaning power of shampoos is very important. Do you think you can improve a shampoo's cleaning power by changing the temperature of the washing water or using more or less shampoo for each wash? Experiment with a range of shampoo concentrations or water temperatures and find out!
- What other qualities of a shampoo are important for customers and could be tested? Do some research and find out about other shampoo evaluation tests. Here are some ideas that you can look up: wetting behavior, percent solids, viscosity, conditioning, detergency—or create your own tests!
- Whereas all the tests in this experiment measure a specific quality or property of each shampoo, the results will still not tell you if people actually like the shampoo or not. Design an experiment in which you can test how customers rate each shampoo's performance. For your survey, you could, for example, use real hair swatches that you wash with each shampoo and let volunteers decide which one looks and feels best.
- If you are interested in more cosmetic science projects and putting other beauty products to the test, check out Science Buddies' project Cosmetic Science: Testing Lip Balm Recipes.
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