Sodium Hydroxide and Potassium Hydroxide Soapmaking

April 09,2023

Making Soap with Sodium Hydroxide and Potassium Hydroxide

Lye (sodium hydroxide or potassium hydroxide) is a necessary ingredient when producing liquid or bar soap. Saponification is the process through which oils are converted into soap.

Lye is extremely caustic, therefore use suitable safety equipment before attempting to create soap. Prepare in a well-ventilated place away from children, pets, and individuals who may be unaware of the hazards.



The main chemicals required for soapmaking are sodium hydroxide (commonly known as Lye or Caustic soda) and potassium hydroxide. These chemicals combine with fats/oils to generate glycerin and soap, which are fatty acid salts. The precise fatty acids in the oils/fats you use will determine the qualities of your soap.

Soap is a material composed of glycerin that has been chemically bonded to three fatty acids. When this is combined with a strong basic (such as NaOH or KOH), the triglycerides of the fats/oils breakdown and create soap molecules.

The hardness of soap is determined by the acidity and alkalinity of the components. Soapmaking oils are moderately acidic, with pH values ranging from 0 to 7.

When coupled with an alkali, the alkali aids in the saponification of fats and oils and the melting of soap bars. When you mix a strong acid with alkali, the acid consumes some of the alkali, causing your soap to be less than it should be.

To compensate for the acid's consumption, you must add more alkali to your mix. This can assist to avoid the typical issue of unsaponified oil/fats in your soap.

It also aids in the prevention of soap volcanoes, which can be generated by fast saponifying oils or a too-warm mixture.

Some people use various acids in their soap batter, such as citric, acetic, or lactic acid, to prevent soap scum, extend the shelf life of their final soap, and/or make it tougher. Calculate how much of each sort of acid you need to blend with your sodium or potassium base and add it to your lye solution accordingly.

Another frequent method for hardening soap is to combine it with calcium carbonate. This is found in rock salts, but it can also be created at home by combining equal parts glycerin and calcium oxide.

Some DIY soaps are also meant to be dual lye, which means they include both NaOH and KOH. This allows you to make a firm bar of soap without needing to combine two lye solutions. However, this can be a tough task that necessitates some knowledge of the chemistry behind the combination. It is better to reference a scientific soapmaking book or one of the many online soap calculators.



Lye is the main ingredient in soapmaking that transforms oils and butters into lathering soap. While lye can be manufactured from a variety of chemicals, the majority of lye used in soapmaking is either sodium hydroxide or potassium hydroxide.

These are both white, solid, corrosive alkali metal hydroxides. You may be familiar with the terms lye (sodium hydroxide) and caustic soda (potassium hydroxide).

While both chemicals are soluble in water, KOH-based products are slightly more soluble than naoh-based products. Because of the way these chemical molecules react with water.

The reaction between these chemical compounds and water is highly exothermic, which means it generates heat and releases hydrogen. This is a wonderful thing for many reasons, but it may also be a problem if these compounds are used in the incorrect proportions.

Too much KOH can make the soap softer and harder, while too much NaOH can make the soap more difficult to rinse. This is why it is critical to select the proper lye combination for your recipe.

Potassium hydroxide has a somewhat lower molecular size than sodium hydroxide, allowing it to penetrate oil molecules and break down the oil more quickly. It is also more soluble, making it easier to eliminate oils after rinsing.

This makes it a great choice for a soap that needs to dissolve a thick coating of caked-on oil. It is also effective on metal surfaces with baked-on grease or oil.

It is also an excellent alternative for soaps that require the dissolution of a thick coating of glycerin. However, utilizing KOH as the principal lye in your recipe will require more time and work than using NaOH to achieve the same results.

Both of these compounds are widely available in a number of forms, including flakes, pellets, and a 50% water solution. This allows you to purchase only the amount required for your specific recipe. When purchasing a lye solution, make sure to thoroughly read the package and observe all safety precautions. When working with lye, you should wear gloves and goggles and focus on the task at hand because it may be quite corrosive.


Sodium Hydroxide and Potassium Hydroxide are alkali chemicals that are utilized in the production of soap and skin care products. They can saponify fats and oils, allowing them to lather into soap, and they can aid to establish the pH of a soap or other product.

These chemicals can also cause chemical burns if they come into touch with your skin or if you breathe in their fumes, so use caution when using them. Wear rubber gloves and keep lye solutions out of reach of children.

When working with these substances, you should also wear protective eyewear because they can cause significant chemical burns if they penetrate the eyes. If you have children, it is even more crucial to keep them away from the kitchen or other areas where these items are utilized because they are easily accessible.

To begin producing your own soap, you will need a few supplies. A digital scale, a bucket or jug (ideally glass or stainless steel), and a few implements for measuring, mixing, scraping, and putting the soap batter into your moulds.

When preparing a lye solution, a thermometer is essential. It will protect you from overheating the lye and water. Check the temperature of your lye solution frequently because it will swiftly rise, so don't let it get too hot!

To make the lye solution, you'll need some high purity (at least 95%), fully dry, and flowable Sodium Hydroxide flakes. You'll also need cooled distilled water to avoid overheating.

Always dissolve the lye flakes in modest amounts of water. If you add too much lye at once, it can react and bubble aggressively, which is harmful for you and anyone around you!

When handling any alkali chemical, you should also wear a decent pair of nitrile or rubber gloves. If sodium or potassium hydroxide comes into touch with the hands, it can cause severe burns.


When manufacturing soap at home, you'll frequently come across lye products with somewhat different technical names: sodium hydroxide (NaOH) or potassium hydroxide (KOH) (KOH). It can be difficult to determine which one to utilize when determining how much of each to use to make your recipes work.

NaOH and KOH are both strong alkalis, which means they react with lipids to generate soap. They are used to make both bar and liquid soap, though the latter is more popular.

Saponification is the process by which water and lye are added to oil or butter to create sodium and potassium soaps. When the soaps cool, they solidify or melt to form hard soap bars or soft liquid soap.

Lye granules are a strong and dangerous hazard that can cause severe pain if touched, so wear gloves and eye protection when working with them. You should also take precautions to ensure that you are in a well-ventilated environment.

If you come into touch with lye, thoroughly rinse your skin with water and wash it off as quickly as possible. If you have children or pets, be certain they are not exposed to it.

Personal protection equipment can also be purchased to assist keep you safe from lye fumes and burns: safety glasses, chemical-resistant gloves, and appropriate ventilation are all recommended when dealing with lye. On their Buy Protection website, Certified Lye(tm) sells these things (and more!).

When you mix lye solution, you will produce a lot of fumes that can irritate your eyes and lungs. Always follow the instructions on the lye container and avoid mixing it too close to your face.

Some lyes may react with metals such as aluminum, producing sodium aluminate, a highly exothermic and potentially explosive chemical. Because this reaction is extremely harmful, you should never mix lye and aluminum in a closed container.

Using glass or Pyrex containers during a lye reaction is not recommended. This is because they are brittle and readily fractured by the heat of the lye reaction. Instead, choose stainless steel or plastic containers that are not prone to shattering and do not include any lye-reactive ingredients.