SOAP PREPARATION

Introduction

Soap is one of the commercial products essential to our health as it promotes cleanliness and preserves our skin from the scorching heat of the sun and from external pollutions such as dust, germs and bacteria.

Soap is one of the oldest and most important cosmetic and personal care products. Soap is a product used in conjunction with water for washing and cleaning. It usually comes in a solid molded form but may also come in the form of liquids dispersed from dispensers. Soap typically contains surfactants that, when applied to a soiled surface in combination with water wet the dirt and effectively holds particles in suspension so it can be rinsed off with clean water.  

Soap is produced by the saponification of triglycerides. In saponification, triglycerides reacted with a strong base such as potassium hydroxide or sodium hydroxide to produce glycerol and fatty acids salt. The salt of the fatty acids is called soap. Fatty acids are seldom found as free molecules in nature but are most often a part of a larger molecule called triglycerides. Triglycerides consist of a three-membered carbon chain with a fatty acid bonded to each of the three carbon atoms in the glycerol backbone. The bond between the fatty acid and the glycerol backbone is referred to as an ester linkage. In the saponification process the ester linkage is broken to form glycerol and soap.

Objectives

1.      Understand the rationale behind the use of the different types of ingredients in a soap formulation.

2.      Understand the acid-base reaction (saponification process) by which soap is produced.

3.      Evaluate the quality of the products that have been produced.

Materials

Olive oil, vegetable shortening, coconut oil, potassium hydroxide, sodium hydroxide, glycerin, alcohol, castor oil, distilled water, fragrance and essential oils, colourants, honey, oatmeal, tea, coffee, cocoa, vitamin E and camphor.

Apparatus

Beakers, soap molds, water bath, measuring cylinders, glass rods, evaporating dish and thermometer.

Amount of ingredients for a bar of soap:

Coconut Oil	19.6%	15.68 g
Olive Oil	19.6%	15.68 g
Vegetable Shortening	29.6%	23.68 g
Sodium Hydroxide	9.9%	7.92 g
Distilled Water	20.9%	16.72 g
Honey	0.17%	0.136 g
Oats	q.s	q.s
Colourants	q.s	q.s
Fragrance/Essential Oils	q.s	q.s

*Weight of soap: 80g

Procedures

1.      The molds for the soaps are cleaned and dried completely. The mold is greased with petroleum jelly.

2.    The fats and oils for the soaps which are coconut oil, olive oil and vegetable shortening are weighed using weighing scale.

3.     The fats and oils are then mixed in a beaker and the mixture is heated to around 40-50℃. The mixture is then removed from heat once there are one liquid oil phase.

4.     Sodium hydroxide and water are weighed. Sodium hydroxide is then added into the water and stirred until it solubilise. Since the mixture produces heat, it is cooled down after stirring.

5.  The dissolved sodium hydroxide is then poured into the warm oil mixture in the beaker. The oil became opaque as soon as sodium hydroxide is added. They are mixed in circular motion constantly for 15 minutes and then left to rest for a while. It is then mixed again until thickened.

6.    Mixing is stopped when the mixture formed trace. Fragrance, colourant, oats and honey are then added in the mixture. The mixture is mixed well.

7.      The soap mixture is then poured into the mold. The mold is covered with a cloth and left to hardened for 24-48 hours.

8.      After a week, evaluation of products are conducted.

Discussion

Saponification is a reaction which an ester is heated with an alkali, such as sodium hydroxide which then producing a free alcohol and a carboxylate salt, especially alkaline hydrolysis of a fat or oil to make soap. Soap molecules have both properties polar and non-polar. The cleansing action of soap is determined by its polar and non-polar structures. The long hydrocarbon chain is non-polar and hydrophobic (repelled by water) while the "salt" end of the soap molecule is ionic and hydrophilic (water soluble).

In this soap making, the chemicals or items used are olive oil, vegetable shortening, coconut oil, sodium hydroxide, distilled water, fragrance and essential oils, colorants, honey, oatmeal and coffee. All these ingredients have their own functions and uses in making the soap.

The table below represents the functions of each ingredient:

Ingredients	Functions
Olive oil	-As the main ingredient -As a humectant -Moisturize the skin
Vegetable shortening	-For hardening and conditioning
Coconut oil	-To produce lather and form more bubbles -To add hardness to the soap
Sodium hydroxide	-Important for the saponification process -To dissolve grease, oils, fats and protein     based deposits
Distilled water	-To dissolve sodium hydroxide for   preparation of saponification
Fragrance and essential oils	-To improve the scent of the soap
Colorants	-To improve the appearance and  attractiveness
Honey	-Increase lather production -As antimicrobial
Oatmeal	-As exfoliation -As moisturizing
Coffee	-As exfoliation

The evaluation tests that had been carried out were the scent produces by the soaps, the pH evaluation for the soap, the lathering effect of the soaps and the melting point of both soaps as well as the time taken for it to melt.

 

For both soap A and soap B, they produced the pleasant scent as we inserted fragrance and essential oils after the trace are formed during the soaps making. For the pH evaluation, we use the litmus paper to indicate the pH properties of the soap. When blue litmus paper is used, it remains unchanged meanwhile for red litmus paper, it turned blue . This shows that the soaps have a pH within the range of above 7 until 14 where it is in alkaline range. The soaps have the lathering effect as we rub our hand with the soap. The bubbles that produce are white, foamy and quite a lot as the ingredients such as coconut oil and honey play the role in producing the lather.

For soap A, the melting point is 54^oC and it takes 18 minutes to melt while for soap B, the melting point is 58^oC and it takes 12 minutes to melt. However, the phase during this temperature, most part of the soap is still in solid phase but got some that already melt. This shows that the soap has high melting point. This is because the higher the melting point of the soap, the more stable is the soap so that when we leave it in the room temperature it will not melt and break easily.

For addition, both soap A and B do not cause any skin irritation and both are effective in removing dirt or greasy oils. As we know, soap has both the polar and non-polar properties. The hydrophilic ends of the soap molecules will attached to the water surrounding meanwhile the hydrophobic ends of it will stick to the dirt or oils. The removal of all this dirt and oils is assist by the motion of rubbing on skin in order to effectively remove the dirt. The foam is created when the surface tension of water is reduced and air is mixed in causing bubble formation and also by the addition of coconut oil it forms more bubbles. 

Lastly, the addition of oatmeal and coffee is to produce exfoliation. It is important as it involves the removal of dead skin cells on the skin’s outermost surface. This somehow can improve the function of the soap. Besides, soap also should have moisturizing and conditioning properties to have better effect on skin when used.

Only red litmus paper turned blue.

Soaps produced foam.

Shortcomings

When we were preparing the ingredients of the soap, we weighed each of the ingredients according to the calculation that have been made.  However, this leads to the incorrect composition of the intended product due to the properties of some ingredients that tends to stick on the beaker. This causes the inaccuracy of the soap formulation. Thus, the preparation must be calculated in excess to avoid any inaccuracy.

Moreover, when we were mixing the ingredients, the mixture of our ingredients take a longer time to harden due to the inaccuracy of the weighed ingredients as the ingredients stick on the beaker. Hence, make our soap take a long time to harden.

      Also, we had problems heating the water bath because it took a long time for the water to be heated. Thus, the water bath need to be heated as soon as experiment is to be started because it take a long time to heat the water.

Conclusion

In conclusion, we are able to understand the function of each ingredient in a soap formulation and also the rationale of using these ingredients. Besides, we can understand the saponification process to produce soap. The reaction between ester and alkali allowed the process to occur. From the evaluation tests, the soaps produced have good scent, are alkaline, able to form foam and have high melting point.


References

1.      Anne Marie Helmenstine, P. (2017, May 12). Saponification Definition and Reaction. Retrieved from ThoughtCo.: https://www.thoughtco.com/definition-of-saponification-605959

2. Cosmetics Info. (2016). Retrieved from Cosmetics Info web site: http://www.cosmeticsinfo.org/ingredient-alphabetical