Building blocks for formulation of soaps

Soaps

1. Building blocks for formulation of soap Presented By : Sourish Ojha Cosmetic and Cosmeceuticals M pharm 2nd sem ,  Gitam university 

2. Contents: Introduction History of soap Objectives  Advantages & Disadvantages Types of Soaps Formulation Ingredients Manufacturing Process SOAP PERFORMANCE EVALUATIONS REFERENCE 2

3. Introduction: Soap is a cleaning agent made from the chemical reaction of fats/oils and an alkali. The most common fats used in soapmaking are vegetable oils like olive, coconut, palm, or other plant oils. The alkali is usually sodium hydroxide, also known as lye. When the fats and lye react, a chemical process called saponification occurs, producing glycerin and soap. The soap can then be hardened into bars, liquid soap, flakes, powders, etc. Soap allows oils and fats to become miscible with water, allowing cleaning action. The nonpolar, hydrophobic end of soap molecules bond with oils, while the ionic, hydrophilic end bonds with water. This allows soap to act as an emulsifier and surfactant. 3

4. SOAP S Soaps are Sodium/Potassium salts of a fatty acid and is made from natural raw materials.  It is the oldest cleansing agent still in use today. For centuries, it was the only known surfactant. When triglycerides in fat/oil react with aqueous NaOH or KOH, they are converted into soap and glycerol. This is called alkaline hydrolysis of esters. Since this reaction leads to the formation of soap, it is called the Saponification process. Although synthetic detergents have replaced soap in many application product categories, it has largely retained its importance for skin cleansing. Popularity of Soaps is due to the fact that:                • It is relatively milder to skin                • Is inexpensive. The first concrete evidence we have of soap- like substance is dated around 2800 BC., the first soap makers were Babylonians, Mesopotamians , Egyptians, as well as the ancient Greeks and Romans . All of them made soap by mixing fat, oils and salts. Soap wasn’t made and used for bathing and personal hygiene but was rather produced for cleaning cooking utensils or goods or was used for medicine purposes. Almost 5000 years ago, it was discovered in ancient Babylonia that mixing animal fats with wood ash and water created a cleansing substance. The first soaps were used in the textile industry and for skin diseases. 4

5. Soap is a cleaning and lubricating product produced from the chemical reaction between oils/fats and alkali salts. The oils and fats provide fatty acids like oleic acid, stearic acid, etc. Common oils used include coconut oil , palm oil , olive oil , etc. Each contributes different fatty acid profiles. The alkali generally used is sodium hydroxide, also known as lye. It ionizes the fatty acids into sodium salts. This saponification reaction produces the sodium or potassium salts of fatty acids, which is soap, and glycerol as a byproduct. Soaps are anionic surfactants, meaning they have a hydrophilic end and a hydrophobic end, allowing them to emulsify oils and solubilize grease. Key properties of soap include the hardness, cleansing ability, and lathering determined by the oils/fats and alkali used. Additives like fragrance, moisturizers, exfoliants, and vitamins can be included in soap formulations. Soaps are used for cleaning, hygiene, lubricating and other purposes by acting as emulsifying and wetting agents. Objectives: 5

6. Advantages: Soap is cheaper and readily available. It works well for cleaning with soft water . Soaps are 100% biodegradable( decomposed by micro organisms present in sewage ), therefore, they do not create water pollution. Very effective as a bactericide . Excellent everyday cleaning agent Good bioavailability. Through the ages soap has been used to cleanse, to cure skin sores, to dye hair, and as a skin ointment. Multipurpose cleaning tool of skin, cloths and the area that we live in.  Disadvantages:    It does not work well with hard water or forms less lather with hard water.  When used in hard water it produce scum.   Soap is not suitable for washing woolen garments because it is basic in nature and woolen  garments have acidic dyes.  Soap are less effective in saline and acidic water .  They have weak cleansing properties than detergents. 6

7. KEY POINTS  SOAP SYNDET COMPOSITION: Made from natural fats or oils that undergo saponification (reaction with an alkali like sodium hydroxide or potassium hydroxide). Composed of synthetic surfactants, typically derived from petrochemicals or plant-based sources. pH: Generally has an alkaline pH, typically around 9-10. Designed to have a pH closer to the skin's natural acidic pH, usually between 5-7. CLEANSING ACTION: Cleansing action is based on the formation of insoluble salts (soap scum) when combined with hard water minerals like calcium and magnesium. Cleansing is achieved through the action of synthetic surfactants, which can effectively remove dirt and oil without forming insoluble salts. SKIN COMPATIBILITY: Can be drying and irritating to some individuals, especially those with sensitive skin, due to its alkaline nature. Generally considered milder and more compatible with the skin's natural pH, reducing the risk of dryness and irritation. LATHER: Produces a rich, creamy lather when combined with water. Can produce a similar lather to soap, but some syndets may have a different lather quality or require additional lathering agents. HARDNESS AND LONGEVITY: Tends to be harder and longer-lasting due to the nature of the saponification process. Can vary in hardness and longevity depending on the specific formulation and additives used. ENVIRONMENTAL IMPACT: Generally considered more environmentally friendly as it is biodegradable and derived from natural sources. Some synthetic surfactants used in syndets may be less biodegradable or have potential environmental concerns, although efforts are being made to develop more sustainable syndet formulations. VERSATILITY: Limited in versatility due to its alkaline nature and tendency to form insoluble salts with hard water minerals. Can be formulated for various purposes, such as hand washing, laundry detergents, and dish soaps, due to their compatibility with different water conditions. 7

8. Solid soap : it is a bar that can be of different shapes (rectangular, oval, round, cubic, etc ). It is also called  toilet soap , because it can be placed easily on the edge of the sink. Liquid soap : it makes certain uses easier, such as washing floors or dishes. It also becomes a shower gel or hand cleansing cream.
 
 Soap flakes/ Transparent soap : it must be diluted in hot water and is used to wash floors and linen.

 Laundry/ Powdered soap : it is used for household appliances or for laundry.

 Shaving/ Mousse soap : the most common use is in shaving foam.

 Medicated/ Antibactreial soaps :  As directed and under the guidance of a healthcare professional, especially for prolonged use or specific skin conditions.  TYPES OF SOAPS   8

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12. FATS AND OILS  ALKALIS  ADDITIVES USED   A) Antioxidants B) Whiteners/ Opacifying agents C) Perfume/ Flavors/ Fragrances D) Colors   E ) Surfactants F ) Emollients  G) Anti-bacterial H ) Water FORMULATION INGREDIENTS 12

13. 1.Fats and oils : The typical ratio is 80:20 with Palm (Hard 80) and Palm Kernel (Soft 20) We excel at adjusting and manipulating these ratios, creating speciality soap bases with innovative speciality oils and additives. We can use a vast array of oils in our soap manufacture , however, most suppliers will use a standard range of oils as seen below:  Vegetable Oils Palm Oil Palm Kernel Oil  Coconut Oil  Olive Oil 13

14. Fats and Oils (cont...) Fat mixture containing saturated and unsaturated and long and short chain fatty acid in satiable proportion are used. Saturated fatty acids with 12 to 18 carbon atoms are used. Eg. lauric, myristic,palmitic , stearic and oleic acid In the United States of America and Europe tallow has long been used as a basic ingredient of soap.To improve the solubility and lathering properties coconut oil is mixed with tallow.  Fish oils, palm oil and coconut oil are also used in preparation of soaps. 14

15. The free caustic alkali is the amount of alkali free to counter and avert the soap from becoming oily. An important raw material in soap making is caustic soda. The soaps consequently span a range of lye concentration from 50 % to 25% The free caustic alkali for toilet soaps was found to be 0.00% to 0.62 % and for laundry soaps it was found between 0.14% to 0.99% Eg : Soda ash can saponify fatty acids & used as a builder in laundry soaps . Caustic potash is used in making soft soaps . Potassium carbonate and soda ash are used to saponify fatty acids 2. Alkalis : 15

16. A)Antioxidants:   These are used to stabilize the soap against rancidity . Anti- oxidants help repair your skin, reduce inflammation, keep your skin fresh and youthful.   Eg . sodium silicate, sodium hyposulphite , sodium thiosulphate , BHA & BHT etc. B)Whiteners and opacifying :   These substances added to soap formulations to provide opacity or a whitening effect, creating a visually appealing and creamy appearance.  Purpose of Opacifying Agents: To provide a dense, opaque, and creamy appearance to the soap, which is often associated with high-quality and moisturizing properties. To help mask or conceal any impurities or discoloration in the soap base. To enhance the overall visual appeal and attractiveness of the soap bar. Titanium dioxide and zinc oxide are used to improve whiteness . Natural i ngredients such as Arbutin , kojic acid, clay, oat meal, starches and glutathione absorb into your skin and temporarily reduce the skins ability to produce melanin.   16

17.  C)Perfumes:   The pH of the soap is around 10.0. The selected perfume should be stable in this PH range. Fragrances are an integral part of soap, providing a pleasant aroma and enhancing the overall experience of using the soap. Here are some key points about fragrances used in soap: The primary purpose of using fragrance as an ingredient in these products is to mask unpleasant aromas or odors from other active chemical ingredients. In the preparation of soaps, some oils are used as natural perfumes in very low percentage. Common essential oils used in soap manufacturing are Bergamot , Rose, Orange, Citronella, Eucalyptus, Lemon, Lime, Peppermint , Lavender, Sandalwood, Palmarosa , Vanilla, musk fragrance, and floral bouquet fragrances . D) Colouring agents: Natural ingredients used are Red- Molasses, cranberries, pomegranates, red beets, Black- Charcoal clay, Purple- Blackberries. 17

18. E ) Surfactant : Primarily responsible for cleansing and lathering. Non-ionic and amphoteric seldomly used.   Eg  :- Alkyl polyglucosidase   Fatty alcohols, Alkyl phosphate esters Methyl glucose ester  Glycerin monosterate Alkyl betaines Polyhydroxy fatty acidAmides   Polyalkylene glycols 18

19. F ) Emollients : Emollients help to counteract the drying effects of soap on the skin. They help to maintain the skin's moisture balance and prevent it from becoming excessively dry or tight. Emollients provide a smooth and velvety after-feel on the skin. Types of Emollients: Oils and Butters: These include vegetable oils (e.g., coconut oil, olive oil, palm oil), nut oils (e.g., sweet almond oil, shea butter), and animal fats (e.g., tallow, lard). Fatty Alcohols: Examples include cetyl alcohol, stearyl alcohol, and lauryl alcohol. Esters: Common esters used as emollients are isopropyl myristate, isopropyl palmitate, and cetyl esters. Silicones: Dimethicone and cyclomethicone are examples of silicone-based emollients. 19

20. 20 G)Anti-bacterial agents:  These are often incorporated into soap formulations to provide additional cleansing and sanitizing properties.  Purpose of Anti-bacterial Agents: To reduce or eliminate harmful bacteria from the skin's surface. To prevent the spread of bacteria and reduce the risk of infections. To provide enhanced hygiene and cleansing benefits. Types of Anti-bacterial Agents: Synthetic Compounds: Triclosan : A broad-spectrum antimicrobial agent effective against bacteria, fungi, and viruses. Triclocarban: Another synthetic antimicrobial compound commonly used in soaps and personal care products. Chlorhexidine: A widely used antiseptic and disinfectant in various healthcare products, including soaps. Natural Compounds: Essential Oils: Certain essential oils like tea tree, thyme, and eucalyptus have anti-bacterial properties. Plant Extracts: Extracts from plants like neem, turmeric, and grapefruit seed have shown antimicrobial activities.

21. 21 H) Water: Water is used to dissolve sodium hydroxide lye so it can react with the oils and start the saponification process. As the soap cures, the water evaporates and creates harder, longlasting bars . Typically, a preparation uses about 22% of liquid.

22. General formula of soap: 22

23. SOAP MANUFACTURING PROCESS:    Cold p rocess   Semi- boiled process Full- boiled P rocess  Continuous saponification 23

24. 1 ) COLD PROCESS : Cold process, mixing of fat and strong alkali is carried out substantially at room temp .  Mixture of fats and alkali is kept under vigorous agitation for approximately 2 hours and the dyes, perfumes and additives are added at this stage. The process does not include the removal of impurities or separation of the glycerin which is produced. Crude soap is drawn off as the bulk of the mixture thickens and is poured as it is into the cooling frames, where the saponification process is carried for one or more days.  Saponification is completed after this mixture is run into frames in several days at warm temperature. Since there is no opportunity to adjust proportions of fat and alkali calculation of quantities to be used should be made carefully . Crude soap is then removed from the frame and cut into the blocks and sent for finishing. 24

25. 2 ) SEMI- BOILED PROCESS: Semi boiled and cold processes are the simplest processes of soap making. In these processes, fat is reacted with strong alkali and strong alkali is nearly equal to that just required for saponification.  The semi boiled process differs from the cold process in the fact that the saponification. Mixture is heated to 70-90°C. Using a steam heated coil to accelerate and complete the saponification reaction.  After the saponification is complete other ingredients like dyes, perfumes and additives are added to prevent them from drying.  It also allows manufacturing waste to be recycled , better incorporation of additives and a wider choice of materials. 25

26. SEMI- BOILED PROCESS :​ ​ 26

27. 3 ) FULL-BOILED PROCESS: In this process, large cylindrical kettles with cone bottoms equipped with open and sometimes with closed coils for steam are used . The kettles are often provided with delivery pipes for fats, water, lye. Process includes:   Saponification reaction:- This is carried out by boiling fat with aqueous alkali together with open steam at 100°C allowing a wider range of fatty raw materials to be used. After saponification takes place, the mass is subjected to several washes using brine. The more intensely the glycerin is washed, lower is the glycerin content of the soap. Graining out & washing :-  After saponification, the soap is grained out by the addition of salt to the boiling mass. Dry salt as well as brine may be used.  The soap rises to the top of kettle in form of rough mass as soap which is called 'kettle wax'.  The washings are carried out by adding water to the kettle mass.  Finishing or Fitting operation :-   The final operation in soap boiling is fitting operation.  Here, the soap is boiled with water & upon standing, the batch will separate into upper layers consisting of neat soap and lower layer consisting of  niger  which retains most of the  colouring  materials, metallic salts & other impurities ​. 27

28. FULL- BOILED PROCESS: ​ ​ 28

29. 4) CONTINUOUS SAPONIFICATION : These processes are used when the production is on very large scale .  Fats are first converted into fatty acids and glycerin using high pressure at 500°C in continuous fat splitting process and fatty acids are reacted with alkali to form soap . This includes counter-current washing and separation . 29

30. SOAP PERFORMANCE EVALUATIONS Lather . W ater rate/use-up of soap bars. Slough/Mush. Cracking  Hardness of soap bars. Feel and sandiness evaluation for soap bars. Stability testing for soaps. Sensory skin evaluations for  soaps. Clinical Evaluations. 30

31. Here are the key points regarding lather evaluation of soap products:  Trained sensory panels rate lather quantity, quality, and quickness on a numerical scale.  Panelists follow a standardized procedure of rotating the soap bar a fixed number of times to evaluate against benchmark products.  Panel testing is useful for analyzing formulation differences and comparing to competitive products. Variables like water temperature, hardness, bar shape/size, and washing method affect lather perfomance .  Panelists require regular training and validation to ensure consistent evaluations.  Laboratory foam height tests like the Ross-Miles method are also used by pouring a soap solution onto itself from a fixed height.  However, lab tests can be misleading as bar shape and solubility influence real-world lather differently than in the test.     Trained sensory panels following set procedures are emphasized for evaluating lather attributes, while accounting for key variables, though lab tests provide supplementary data with some inherent limitations. 1)Lather  31

32. 2)Water rate/use-up of soap bars:  1. Measuring how long a bar lasts under normal use conditions is important for assessing consumer perceived value.  2. The use-up rate is measured by: - Weighing the initial bar - Washing the bar a set number of times with set durations (e.g. 25 washes for 10 seconds each) - Drying and re-weighing the bar - Calculating the percent weight loss  3. Bar shape and size impact the measured use-up rate. 4. The measurement must control for water hardness and temperature variables. 5. For comparing formulations, bars of similar size/shape should be used or bars can be shaved to the same dimensions.  6. To reflect real consumer use, commercial bar sizes and shapes should be tested. A standardized wash procedure measuring weight loss is used to quantify a bar's wear rate, accounting for variables like water quality, bar geometry, and whether aiming to isolate formula effects or mimic consumer conditions. 32

33. Here are the key points regarding slough/mush in soap bars:  Slough or mush refers to the soft, undesirable portion of a soap bar that results from hydration when the bar sits in a wet soap dish.  Slough is measured by: - Placing a pre-weighed bar in a high humidity chamber for a set time - Removing the softened portion of the bar - Allowing the bar to dry and re-weighing - Calculating the percent weight loss as the slough . Syndet (synthetic detergent) bars tend to have higher slough compared to regular soap bars.  High humidity test conditions exaggerate but help differentiate products and formulations beyond typical home use.   Slough can also be measured at room temperature. 6. Manufacturers can select specific commercial bar shapes to minimize slough/mush formation during actual use by consumers.      The slough test exposes bars to high humidity to induce and quantify the soft, mushy degradation, with syndet bars being more prone. Bar geometry can be optimized to reduce this issue in practical usage scenarios. 3)Slough/Mush : 33

34. Here are the key points regarding cracking in soap bars: Cracking refers to the splitting or development of cracks in a soap bar, either along the side seams or anywhere on the bar surface during use.  Cracking of soap bars during normal use conditions is perceived negatively by consumers.  To evaluate cracking, the testing method involves: - Partially submerging bars in water of fixed hardness and temperature - For a set period of time - Drying the bars for 1-2 days - Examining the bars for the presence of any cracks that developed  The ideal outcome is that no cracks should be present in the soap bars after this standardized testing.  Cracking can impact the usability and integrity of the soap bar from the consumer's perspective.                    The key points cover the definition of cracking in soap bars, the negative consumer perception, the standardized testing method involving water immersion and drying, and the desired outcome of no cracking to ensure bar quality and consumer satisfaction.  4)Cracking  34

35.  5) Hardness of soap bars:  Bar hardness is a measure of how resistant the bar is to physical pressure.  It is a mechanical property that can be measured during:                              a) Finishing trials to evaluate machineability (ability to be extruded and processed)                              b) Routine laboratory evaluations . Bar hardness is an important factor for the manufacturing process.  Bars that are too soft may face challenges during extrusion on the finishing line.  Excessively soft bars can also lead to surface defects when being packaged.        Hardness quantifies the bar's resistance to deformation forces, which impacts its ability to be processed and packaged properly during manufacturing, with overly soft bars posing potential issues for extrusion and developing surface imperfections. 35

36. 6)Feel and sandiness evaluation for soap bars:   Bar soaps are typically evaluated for the presence of dry specks and drag.  Dry specks refer to insoluble particles of soap that can occur :                       a) During the manufacturing of the base soap or syndet                      b) From additives in the soap bar formulation .These dry specks appear as distinct bumps                        on the surface of the bar.   To evaluate dry specks, the bar is washed under controlled water conditions, with cooler water temperatures making the dry specks more noticeable.   During and after washing, the bar is evaluated for its feel and appearance, specifically looking for dry specks.   The bar is rated against standard quality bars for comparison.  In addition to dry specks, drag is another attribute evaluated, which likely refers to the frictional feel of the bar during use.   Both dry specks and excessive drag negatively impact the sensory experience when using the soap bar.                 standardized washing procedure is used to evaluate soap bars for the presence of insoluble dry specks that create a sandy/bumpy feel, as well as drag or lack of lubricity, with ratings compared against benchmark quality bars. 36

37.  7)Stability testing for soaps:  All bar soaps should undergo studies to determine the stability of color and fragrance/odor active materials. Stability testing should be conducted on the final packaged product.  For products making antibacterial claims in the United States, the FDA provides guidelines for required product stability testing.  For other regions, stability testing requirements are governed by local and regional regulatory authorities.  Stability testing ensures that the color and fragrance of the soap do not degrade or change significantly over time.  It is an important quality control measure to meet regulatory standards and consumer expectations.  Instability of color or fragrance can negatively impact product performance, aesthetics, and consumer perception. In essence, stability studies on the final packaged product are necessary to verify that the soap's color and fragrance remain consistent, meeting regulatory requirements and preventing quality issues that could arise from degradation over the product's shelf life. 37

38.  8)Sensory skin evaluations for  soaps:  Skin feel and lather are important attributes evaluated from a consumer perspective.  Trained expert panels are used to evaluate various skin feel attributes, focusing on defined parameters.  Products are usually compared against a reference product during panel evaluations.  Examples of skin feel attributes evaluated include time to rinse, skin slip, skin tightness after drying, and skin smoothness.  It can be challenging to characterize small differences in skin feel arising from changes in bar soap chemistry.  In addition to expert panels, home use testing with consumers is conducted to evaluate product performance under normal use conditions. For home use testing, products must be matched in appearance and odor to enable differentiation based solely on chemistry/formulation.  Home use testing with consumers complements expert panel data to provide a more comprehensive understanding of product performance. Both expert sensory panels and consumer home use studies are valuable tools for evaluating and differentiating bar soap products based on skin feel and lather properties. 38

39. 9)Clinical Evaluations : Clinical evaluations of soap products are used to determine how effective the products are on certain attributes, primarily mildness/irritation skin dryness/tight- ness antibacterial efficacy, and deodorancy .  There are several methods of measuring the clinical attributes of a soap bar ranging from trained panels to biophysical instru - mentation . 39

40. REFERENCES 1. POUCHERS Perfumes, cosmetics and soaps 10th Edition ( Edited by Hilda Butler) 2. Industrial Soap Production and Manufacturing Process | Saponification ( chemistryscl.com) 3. Continuous Saponification Plant - Mectech Process Engineers. 4. SAPONIFICATION PROCESS - Saponification Plant 5. Chapter 66: Process Flow Diagram - Soap Manufacturing Technology (zoboko.com ) 40

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