Introduction: Derek and Cameron Made Soap With Chemistry!
There are a lot of fancy soaps out in the world, but not all soaps can satisfy everybody. If you want to create and customize your very own soaps, just follow these simple steps.
Soaps are made of fats, oils, and lye, and the soap is formed from the reactions between these ingredients. Which fats we use depend on the molecular composition and physical properties of the fats. Fats are all different and the properties of each one could play a role into how to soap works.
In order to begin making our soap, we need to gather our equipment.
Step 1: Step 1: Gathering Equipment
In order to mimic the basic processes and methods used to create soap, you will need:
- A hot plate that can heat your fats and oils and maintain their temperature at around 45-54 degrees centigrade.
- A one liter beaker or other container that can contain your ingredients for heating and mixing.
- A scale to accurately weigh your ingredients.
- A thermometer.
- A magnetic stir bar or other method to mix your soap.
- A mold to put your soap in. This can be anything but you must be able to get your soap out of it again so keep that in mind. It is suggested that the mold is also watertight.
Step 2: Step 2: Selection of Ingredients
This is where you get to choose all the properties of your soap. This could be anywhere from the hardness of the soap, how many bubbles it produces, how it smells, and even how well it cleans. Adding adjuncts to you soap will affect the soap as described above.
This online soap calculator will make choosing your ingredients much easier. This will allow you to explore different options for your soap recipes and come up with a recipe that works well for you.
In order to fully understand the concepts behind soap-making, we chose to use only Crisco shortening and lye without any other additives. If you would like to add more to your soap, use the soap calculator to understand what to put in your soap. These additives could include essential oils, dyes, aggregates, or ingredients to add texture. These adjuncts could affect color, scent, consistency, and texture of your soap.
It is important to note that on the soap calculator, you will find INS. The ideal value for this is 160 but it can fluctuate a little.
Step 3: Step 3: the Science Behind Fats
There are three different types of fats; saturated, monounsaturated, and polyunsaturated. It is these fats that play into the qualities of your soap.
Each fat has specific fatty acid chains. If a fat is saturated, the hydrocarbon chain has no double bonds in it. Saturated fats have a much higher molecular attraction than unsaturated fats.
Unsaturated fats contain double bonds which bend the chain. Monounsaturated fats have one double bond, and polyunsaturated fats have more than one. Olive oil is a good example of an unsaturated fat.
Because of their irregular shape, unsaturated fats have a weaker molecular attraction and are usually liquids at room temperature. Saturated fats have a more consistent shape and stronger molecular attraction, which is why saturated fats like Crisco are solid at room temperature.
Unsaturated fats cause your soap to be softer, while saturated fats cause your soap to be harder. Great soaps come from a good mix of saturated and unsaturated fats, so choose your fats and ratios well.
Step 4: Step 4: SAP Value
The SAP (or saponification) value is very important. This is the value that tells how much lye you need to properly react with triglycerides to create a good soap.
To calculate the saponification value of our soap we used the soap calculator to assist us in creating our soap. The calculator gives us values for how much of your shortening and other ingredients that we need for our soap. In our lab we got the 226.8 grams of shortening for our lab. The calculator told us our saponification value which was 0.141 NaOH. That number is a ratio, meaning for every one gram of fats, we need 0.141 grams of lye, or NaOH.
NOTE: Do NOT add too much lye(sodium hydroxide). If you do, your soap will severely burn your skin. Make sure that you do all of your math correctly. Also note if you would like more fat in your soap or softer soap then use less lye than the SAP value gives.
Also note that if there is an excess of unsaponified fatty acids after your soap is made, it will be very soft and will not be very effective at cleaning.
Step 5: Step 5: Lye or Sodium Hydroxide
Our last ingredient is lye, or sodium hydroxide. This can be acquired at a hardware store or online, but no matter where you get it you will need to mix it with water. Make sure to add the lye to the water and not the water to the lye. Adding water to the lye can cause the lye to expand and erupt out of your container, which is extremely hazardous. Always add the lye to the water. The amount of lye you use will depend on the SAP value you calculated.
Warning: Lye is very dangerous and WILL burn you if it comes into contact with any part of you body. So please wear appropriate safety equipment such as goggles, long sleeve shirts, pants, and gloves when handling this chemical.
This lye will eventually go on to be part of a saponification reaction (more on that later). The lye causes the triglycerides, or fat molecules, to go through a process called hydrolysis, which adds water to the triglyceride, effectively changing the molecular structure.
Step 6: Step 6: Making Your Soap
Now that you have all your ingredients and your SAP value calculated, you are ready to start making your soap.
Weigh out all of your oils and fats and place them into your beaker. Put the beaker on the hot plate and heat them to around 45-54 degrees centigrade. Make sure the fats are constantly mixing using your stir bar.
Once all the fats are liquefied, carefully add in the lye. Make sure you are wearing proper safety attire, as the lye will burn bare skin, eyes, etc. Pour it slowly so as not to splash it.
While you're stirring, a little information:
The reaction here is the saponification of fats and lye. There are four molecules at play in the saponification reaction. We are starting with a fat (Crisco), which reacts with lye. This forms glycerol and soap molecules. Soap molecules work because they have a hydrocarbon tail, which will bond with grease, and a polar head, which will bond with water. This is important because these properties make the soap effective for washing off both polar and nonpolar substances.
Step 7: Step 7: Finalizing Your Soap
Once all your ingredients and lye are mixed, try and keep the temperature of the mixture constant at somewhere between 45-54 degrees centigrade. Continue stirring your soap too, as this will eventually tell you when it is ready.
You will know your soap is ready when it becomes very thick to stir. Once the consistency of your soap thickens, it is time to pour it into the mold.
Step 8: Step 8: Molds, PH Testing, and Curing Time
Now that your soap is ready, carefully pour it into the mod of your choice. Your mold can be anything, as long as you can get the soap out again when it has hardened.
Before your soap hardens, grab a pH strip and dip it into the soap solution to test the pH. A pH test will determine the acidity of your soap. You will want the pH to be in the range of 7-9, as anything above or below that will burn or irritate your skin in some way.
In order for the soap to cure fully, you should leave it for at least 24-48 hours in an open, dry area. The curing process can sometimes take longer than this so be patient. When it has hardened fully, get it out of the mold and it is ready to use.
Step 9: Step 9: Cleaning Up
First, clean up your basic equipment that did not have any solution on it.
In order to neutralize any hazardous lye, use vinegar. Vinegar should be poured over your thermometer, beaker, stir bar, and anything else that was in contact with lye. The vinegar neutralizes the chemicals and makes them safe to pour down your drain. Do not miss this step.
Next use soap to clean out any containers that were used with the Crisco and other fats.
Store all your equipment in a safe place.
Step 10: Step 10: How Did Our Soap Turn Out?
Our soap was by far not the ideal soap. It was not perfect, but had some good qualities. Most importantly, it did not burn or irritate the skin and it did not smell terrible. The ratios of fat to lye were good as well. The soap did not burn the skin and was mostly solidified. It is definitely not comparable to a commercial product, though.
However, our soap was also a little too soft towards to top due to the soap not being fully "cooked". It is important to be careful adding other additives to the soap due to the importance of the ratios being exact. If you add too much of something, it could cause it to go hard, soft, not smell great, irritate the skin, etc.
In comparison to other groups in the class, our soap turned out fairly well. There were some that were better, but there were definitely some that did not turn out well or did not become soap at all. Some students added dyes, aromas, or other additives. For example, one group added brown sugar to their soap, and it turned out very well. Others, some using additives and some not, did not even solidify, or smelled very bad. Our soap may not have been the best but this was definitely a successful lab.
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