We all go to the store to buy our soap so as to stay hygienic. However, what many of us don't know is what goes into the process of making soap and what ingredients are in soap, following these steps will allow you to understand the chemical reaction that is occurring when you make soap as well as teach you how to make soap.

To begin this process we need to gather an assortment of the proper fats, and because different fats will have different effects on the soap we need to be careful which fats we use. However before we get into the science and chemistry behind making soap, we need to have the proper tools in order to create a well molded processed soap.

Step 1: Equipment

In order to complete this lab we needed to use the proper equipment, some soap makers will use equipment that is designed specifically for making soap, for the sake of this lab however we just needed equipment that can contain our fats and lye. The choice of what kind of equipment that you will us is up to you, however keep in mind that the contamination of lye is very dangerous so ensure that your equipment can safely contain lye.

The tools:

  • 100ml Erlenmyer flask
  • Water Bath-1000 ml beaker
  • Thermometer
  • Test tube clamp
  • Hot Plate - keep at 45 to 54 degrees centigrade.
  • 6M solution of sodium hydroxide (NaOH)
  • Stir Bar
  • Soap Molds

Now that we have all the proper tools, we need to acquire the proper ingredients..

Step 2: Ingredients

In order to make a consistent soap, we needed to have the right ingredients. The fats and oils you use will directly effect the quality of your soap, in order to ensure you get a quality soap you will need to comprise your mixture of a variety of good quality fats and oils. To figure out the proper amount of each fat and/or oil that you need you can use the soap calculator linked below.

Soap Calculator: http://soapcalc.net/calc/soapcalcwp.asp

The ingredients we used:

Coconut oil (85ml)

Olive Oil (85ml)

Walmart GV shortening (170ml)

Lavender extract (5 Drops)

Lye (11ml)

We used these ingredients in order to create a consistent soap that was made out of natural oils. We chose coconut oil, olive oil, and Walmart vegetable shortening as our fats and oils. We found the specific amount of each fat to use from the soap calculator. The soap calculator, calculates the portions for each fat based on the unique structure and profile of each fat. The soap calculator will also calculate the INS, hardness, cleansing, condition, bubbly, creamy, and Iodine. We won't concern ourselves with the iodine levels, but the iodine levels are a measurement of the amount of unsaturated fats in the mixture. The higher this number is, the softer your soap will be. On the soap calculator you should figure out the quantities of each fat that you want. The quantities that we used are 25% coconut oil, 25% olive oil and 50% Walmart GV shortening. This combination had a score of 151 INS, which is pretty close to the optimal 160 INS so it will do.

Step 3: Lye (Sodium Hydroxide)


Lye is a very toxic and dangerous chemical. Improper procedures could result in severe chemical burns. Keep acetic acid or vinegar close to hand so in case of lye spilling you can neutralize the base and prevent any persons or objects from being too badly damaged. Keep in mind when handling lye, that this compound is used as a drain opener because of how effective it is when eating through organic material so do not let it come in contact with eyes or skin, always wear gloves and safety goggles when handling this compound.

  1. You can purchase lye at a local hardware store or online at various soap making websites.
  2. When you obtain the lye, it will need to be mixed with water before being mixed with fats, remember to add the lye to water, not the other way around. Making a 10.3 molar solution is ideal for making soap.
  3. You will roughly need to use 38% of the weight of your fats for your water weight, the amount of lye will depend on the saponification value that you can get using the soap calculator.

Step 4: Fatty Acid Science

Before we get ahead of ourselves lets talk a little bit about fats and oils. Fats and oils are classified as saturated, unsaturated, monounsaturated, or polyunsaturated. How your fat of choice is classified will directly effect the soap because different fats will have different reactions. The soap calculator allows us to easily see how each fat and/or oil will react. This makes it easy to optimize the chemical reaction and get an idea of how your soap will turn out based on the fats that were used.

A fatty acid, on the molecular level, is a hydrocarbon chain with a carboxyl group at the top of it. If the acid has no double bonds, then that means the fat is a saturated fat. Unsaturated fats have on or more double bonds within the hydrocarbon chain. Unsaturated fats are \ identified as monounsaturated or polyunsaturated fat. A monounsaturated fat has one double bond within the hydrocarbon chain, and a polyunsaturated fat has more than one double bond.

Saturated fats are long and straight, which means that they have a higher melting point than unsaturated fats. Unsaturated fats have double bonds within the hydrocarbon chain, this means they have a lower melting temperature. Also, the more double bonds you have, the easier it is for the molecule to break apart meaning it has a higher melting point. If you think of it this way, butter is a saturated fat, and at room temperature it is solid. Olive oil is a monounsaturated fat and at room temperature it is a liquid.

Step 5: Saponification or Sap Values

The saponification process is one of the most important aspects to successfully making soap. To successfully make soap the fat and the lye go through a process where the fat and oils reduce the basic nature of the lye making glycerol and sodium stearate. Sodium stearate is soap. Now that saponification has happened the lye inside of our solution is no longer harmful. However if you decide you want to be a genius and add vinegar. DON'T. The solution naturally lowers the pH to a safe level.

Although the reaction sets up and makes it safe, time is necessary to full combine all the components. When doing a cold process for soap it can take up to 4-6 weeks. Using a heat source will accelerate the process of the molecules combining and creating a complete soap. The sap value is found by knowing the percentage of the mass of the lye to the fats and oils. The Soap Calculator provides this information when entering in your fats and oils that you are using for your soap.

Your Sap value will be a decimal, ours was 0.135. This gives you a reference point for your soap.

Step 6: Mixing Procedure

The solution was placed on top of a stir, heat plate and was lightly heated and heavily stirred to thicken the solution. The solution was heated to 57-64 degrees Celsius to have maximum efficiency when making your soap.

The solution was stirred until the contents began to thicken. This means that The Sap process is working. This process can be quickly executed or take a long period of time, generally an hour is the longest time period to wait.

After your soap has thickened it is ready to be put into a mold and become hard.

Step 7: Molds and Extracts

To make sure your soap is completely safe, check the soaps pH level and make sure it is within a 6 to 8 range which is a safe balance close to neutral.

At this point in the process you can add a variety of smells, colors, and shapes to individualize your soap. A mold can be any type of pan, tray, tupperware or other type of liquid holding container.

The container must have a type of cookie sheet or wax paper to allow for the soap to be easily removed without breaking or crumbling leaving the pan to clean easily.

Extracts will make your soap smell less like oils and more like your favorite scent. We used lavender extract to add a calming effect to our very soft soap.

Step 8: Clean Up

To clean your supplies successfully, all of your lab equipment has to be in a neutral pH range.

The only item that is required to be handled with care is the beaker that held your 10 point molar solutions of lye with a pH level of 13.

Add vinegar to neutralize the basic lye. Vinegar does this by being acidic.

Using pH paper, test the pH level of the vinegar, lye mix. If the solution is between 6 and 9 your solution is safe to pour into the sink.

With the other lab equipment: rinse thoroughly and set out to dry.

Step 9: Conclusion

Through this process we learned several ways of making soap. One way was correctly executing the lab given to us.

The second way was trial and error using equations to get us back on track from a mistake.

And the third was how people hundreds of years ago were able to make soap which is amazing due to the fact that my group and I made mistakes in a college lab.

This process was a good team building exercise with my friends it taught all of us that soap is relatively easy to make if done correctly.

If given the chance my group mates and I would do another lab of this type again gladly.

Nice scientific explanation of the process. I have been making unscented soap for a number of years using saved bacon fat from kitchen use. I'd rather make soap once a year then discard the fat. I think the sight of flasks, and the use of Molar concentration terms can scare away some potential soap makers. My soap making consists of using melted bacon fat combined with lye in a ceramic crock pot stirred with a kitchen stick blender. Measurements are made with pyrex glass measuring cup and graduated measuring spoons and a candy thermometer. I make unscented soap that I routinely use for hand washing and bathing. It all started years ago when I wanted an unscented soap for my personal use. Better living thru chemistry....kitchen chemistry that is.
<p>How did the finished product turn out? Do you have a photo of it out of the cup?</p>
<p>The soap is still going through the saponification process, as stated above it may take 4 to 6 weeks. </p>

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