A Guide to Soap Making Supplies: Lye, Preservatives and Fatty Acids

Want to kickstart your soap making venture effortlessly? Prep up your knowledge on soap making essentials with this curated handbook that covers everything from lye to acids used in the soap making process! 

It is true that the idea of making homemade soaps can seem a bit overwhelming in general, especially for the newbies in this domain. There is a lot to catch up on when it comes to the different kinds of processes, supplies and ingredients involved in making soaps, and at times knowing too little or too much can have adverse effects on your entire soap making process. And for that reason, if you're worried about leaping into this exciting world of soap making, we've got you covered!

From soap making lye to preservatives and fatty acids, here's a complete guide on everything you need to know about soap making supplies and ingredients for a smooth soap-making experience.

Soap Making Lye

When it comes to making cold processed soaps, there's still a lot of unboxing and clearing up to do regarding the ingredients, especially in the case of addition and handling of lye.

Though lye is an essential component in the process of soap making, it is still referred to as "that" ingredient by the newbies in the soap making process for particular reasons. But ever wondered what's all the fuss about lye in the soap making sector? Read on to find out more about lye, its role in soap making and its handling for an effortless soap making experience!

What is lye in soap?

Lye is a chemical compound that is essential in the soap making processes, primarily used to maintain the pH levels and to execute the reaction between oils and butters present in the soap. This reaction between the oils and butters with lye is known as saponification and is one of the most crucial steps in the preparation of soaps, shampoos, and other cleaning products.

Although there are various forms of lye available in the market that are derived from different alkali elements, lye is scientifically referred to as sodium hydroxide, which is a caustic chemical of sodium salt. One common misconception about lye is that it is a synthetic chemical that makes soaps seem a chemically derived product, which is obviously not correct. Indeed, lye isn't organic, but lye or sodium hydroxide is technically a naturally derived substance, and adding it to your soap doesn't make it any less natural or unsafe for usage.

When adding lye in soap, make sure that you take help from saponification charts and lye calculators to accurately calculate the amount of lye to be added to your specific soap mixture.

Is lye dangerous?

Though lye is a corrosive substance in its pure form, adding lye in soap can do absolutely no harm to your skin and health. This is because all of the lye that you've added to your soap mixture reacts with the oils, butters and other ingredients present in the mixture, which is what happens during the saponification process. After saponification took place, there won't be any lye (in its pure form) left in the soap mixture.

However, care must be taken while handling lye before mixing it into the mixture, like wearing protective gloves and goggles while pouring the lye. Keep in mind that the corrosiveness of lye does not differ both in its bead and liquid form.

Sodium Hydroxide Lye

Sodium Hydroxide or Lye is undoubtedly one of the most popular soap making ingredients used by soap making professionals and beginners alike.

With the chemical formula NaOH, sodium hydroxide lye is a rather corrosive chemical in nature, and because of that, it should always be handled with utmost care while adding it to water or any solution. If you're a beginner looking for suitable lye for your cold-processed soaps, sodium hydroxide is the best pick for you!

Potassium Hydroxide Lye

Potassium Hydroxide or KOH is another popular saponifying agent in the soap making domain, namely for preparing liquid soaps that include liquid handwashes, dishwasher liquids, and laundry soaps.

When it comes to the preparation processes, the preparation of liquid soaps differs considerably from that of bar soaps, and this difference is mainly because liquid soaps are 'hot processed', while ordinary bar soaps are 'cold processed.' Keep in mind that while adding potassium hydroxide to water, it'll react with a muted fizzy sound. Also, for storing potassium hydroxide, make sure that it is kept in a cool dry place so that it doesn't come in contact with moisture (potassium hydroxide is highly hygroscopic and can attract moisture from surroundings).

Handling Lye Safely

That being said, let's now discuss some essential precautionary measures to be taken while handling and pouring lye into the liquid, starting with its pouring technique and reactivity with water. When adding lye to water, always make sure that you add the lye to the water first and not the other way around. Adding water to the lye first will cause the reaction to be highly exothermic, which will produce a splash of heat and cause serious burns.

Also, while pouring lye into the liquid, make sure that you wear safety goggles and gloves to prevent burns and serious injuries. Make sure that you use a stirring spoon made of either stainless steel or silicone and not made out of wood.

Best Preservatives for Soap Making

Take a look at some of the most popular and favoured soap making ingredients that keep your soaps fresh and rejuvenated for much longer!

Sodium Metabisulphite (SMBS)

Sodium metabisulphite, also known as sodium pyrosulphite, is widely used as an effective preservative and disinfectant not only in the soap making industry but in the food and packaging sector as well. With the chemical formula Na2S2O5, SMBS usually appears in powdered form or its white crystalline state.

Apart from its preservative nature, SMBS is also known for its excellent antioxidant and antimicrobial properties in maintaining the shelf life of products. Since it is a strong reducing agent, sodium metabisulphite prevents oxidation and inhibits the growth of bacteria and mould triggered by the natural chemical reactions between the ingredients in the product. Including sodium metabisulphite in your soap making process can increase the shelf life of your soaps and maintain the quality of the ingredient formulation of the soap content.

As for the safety concerns of this preservative, SMBS is declared as a safe preservative under the category Generally Recognized As Safe (GRAS) and reportedly has no harmful side effects on usage.

Tetrasodium EDTA

There is no perfect batch of soaps made without adding this ingredient, and that is tetrasodium EDTA! Tetrasodium EDTA or tetrasodium ethylenediaminetetraacetic acid is used as a 'chelating agent' in the soap making process, which simply means that it helps the soap to induce a better cleansing effect even in hard water. This is because it deactivates the calcium and magnesium ions present in hard water so that it suppresses the degradation of the constituents in the soap. That being said, tetrasodium EDTA is great for maintaining the texture, consistency and fragrance of your soaps and preventing them from going rancid.

Is tetrasodium EDTA safe?

According to the Cosmetic Ingredient Review Expert Panel, tetrasodium EDTA is safe to use as an ingredient in skincare and personal care products.

Although this preservative is known for its potentially high penetration effects on the skin, the Cosmetic Safety Database declares tetrasodium EDTA as an overall 'low health hazard' in products like soaps, shampoos, and cosmetics.

  • Always make sure that the preservative is added in small amounts as high usage of EDTA can gradually lead to certain skin diseases. Being a derivative of formaldehyde, tetrasodium EDTA is known to be a 'penetration enhancer,' which means it can weaken the skin's natural barrier and potentially allow the entry of harmful components into your skin.
  • Never add tetrasodium EDTA to a saturated lye solution, as it can cause precipitation of scum in soap.

Propylene Glycol

Looking for a preservative for your soap that is completely safe and beneficial for your skin? Then propylene glycol is the right pick for you! Not only does it have amazing antibacterial properties (which makes it a good preservative), but it is also a humectant, which means that it has a great moisture-locking capacity that can benefit those with dry, flaky skin. And for that reason, adding this ingredient to the process can help with premature skin ageing by ensuring hydration.

Moreover, according to skin experts and dermatologists, the presence of propylene glycol in skincare and personal care products can make them ideal for acne-prone skin and have the ability to clear away spots and pigmentation of the skin, thanks to its moisturizing properties. Real talk: this ingredient is one of the best ingredients that you can have in your soap!

Top Fatty Acids in Soap Making

Create the most healthy and refreshing batch of soaps with these natural fatty acids that are most beloved by soap making experts!

Lauric Acid

If you want your soap to be extra foaming and fluffy with excellent cleansing action, then lauric acid is the pick for you!

Lauric acid is a saturated fatty acid with the chemical formula C12H24O2 and is a natural acid derived from plant and animal-based fats. Although it melts pretty rapidly when mixed with boiled water, lauric acid remains solid at room temperature.

Despite its popularity in the soap making industry, lauric acid is known for its medicinal properties, particularly in treating internal and external infections that affect the human body. Being a saturated acid, lauric acid has the ability to solidify your soap and enhance the cleansing action of the soap to a great extent. When it comes to the matter of safety, lauric acid is non-toxic and completely safe to use as an ingredient in soaps and other skincare products.

Myristic Acid

Myristic acid is a water-soluble fatty acid that is commonly used in making soaps, shampoos and gels. With the chemical formula C14H28O2, myristic acid is often used as a surfactant and an emulsifier in personal care products enabling them to suspend oil and dirt in water more easily by stabilizing it. Natural oils like coconut oil, palm oil and babassu contain high levels of myristic acid and are usually incorporated in skincare products like facial cleansers and other personal care products.

Just like other saturated fatty acids, myristic acid is known for its foaming action and hardening of soap in making cold processed soaps. Apart from its usage in cold processed soaps, myristic acid, because of its water solubility, is also widely used in making liquid soaps as a thickening and foaming agent, making it the perfect ingredient for both bar and liquid soaps alike!

Stearic Acid

Want your soaps to be moisturizing and hydrating for the skin? One answer: Stearic acid. Being a long-chained saturated fatty acid with the chemical formula C18H36O2, stearic acid is commonly used as a surfactant in the soap making process that enables water and oils to bind together to effectively cleanse out dirt and oil from the skin. In addition to that, including stearic acid in soap making can effectively stabilize, thicken and produce foaming in cold processed soaps.

Although it is considered 'mild and safe' to use according to the Cosmetics Database, stearic acid is not the best when it comes to treating sensitive skin as it can irritate the skin. Despite its prevalence in the soap and skincare industry, this ingredient is a popular hardening component in candles as well.

Palmitic Acid

Palmitic acid is a saturated fatty acid that can produce stable, bubbly lather in soaps. Being an emollient, adding palmitic acid in soap can enhance its moisturization properties that will soothe and nourish your skin immensely.

Speaking of its origin, palmitic acid can be naturally derived from palm oil and cocoa butter, which are both popular (and beloved) ingredients in making cold processed and melt and pour soaps. Palmitic acid is known for its role in producing soft creamy lather in soaps which adds to the cleansing action of the soap by preserving the moisture barrier of the skin. That being said, palmitic acid is definitely an all-in-one ingredient to have in your soap making process!

Citric Acid

Talking about soap making acids that are not necessarily fatty acids, citric acid is a gamechanger when it comes to stabilizing (lowering) the pH of your bar or liquid soap. For this very reason, citric acid is often termed by soap making professionals as a 'neutralizer.'

Naturally derived from cane sugar and corn, adding citric acid in soap making routine is definitely a win-win because of its excellent cleansing action and its ability to get rid of soap scum that forms in hard water. Apart from that, citric acid is also used as a preservative in making cold processed soaps as it prevents them from going rancid. Make sure that if you're adding citric acid to bar soap, the suggested percentage is about 0.5 to 2 percent of the total weight of the mixture.


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