Introduction to Soap Making
What is soap?
Soap has been produced around the world for millennia. Soap is primarily made for its use as a cleansing agent, however it is also used widely in industrial settings as an ingredient in grease and other industrial lubricants. According to Wikipedia, the earliest known soap recipes were recorded on ancient Babylonian clay tablets around 2800 BC. Systematised soap making industries first appeared in Syria and other Middle Eastern countries around the eighth and ninth centuries AD.
Soap is technically a sodium or potassium salt of a fatty acid – a type of salt compound that is produced as a result of the chemical reaction called ‘saponification,’ which takes place when fatty acids (plant oils, butters or animal fats) are emulsified with a sodium or potassium hydroxide (alkali – ‘lye’) solution. (See my soap making terms page for more information).
Prior to the development of modern soap making ingredients, ashes were used as the alkali to make soap. In modern times, the primary alkali used in handcrafted soap making is sodium hydroxide, otherwise known as caustic soda (NaOH). Potassium hydroxide (KOH) is another type of alkali that is used to make liquid soap. Both sodium hydroxide (bar) and potassium hydroxide (liquid) soaps can be made by home soap makers.
This video provides a comprehensive introduction to soap making, essential information about safe handling practices for sodium and potassium hydroxide, and full safety information necessary for all soap makers.
The handmade soap making process
There are two main approaches to soap making available to the home soap maker – the ‘cold-process’ and ‘hot-process’ methods. The formulation of soap recipes and much of the soap making process is similar between these two methods, however as the names suggest, in cold-process soap making the soap batter is mixed and poured at room temperature (or slightly warmer) with no additional heat added, while the hot-process method includes additional heating of the soap batter throughout the mixing process to accelerate the saponification reaction. Further detail on these methods is provided on my soap making terms page.
What about melt and pour soap? The ‘melt and pour’ method utilises pre-made soap bases that are formulated differently from hot and cold processed soaps, which enables them to be easily melted and mixed with other additives (colours, fragrances, botanicals etc.) before moulding again to the desired shape. I have never made soap from a melt and pour soap base, or made my own melt and pour soap base from scratch, but it can be done and is a method enjoyed by many hobby and professional soap makers.
The majority of soap recipes demonstrated on my soap making channel use the cold-process method, which I generally prefer due to its ease and simplicity for beginner soap makers. It is interesting to note that while hot processed soaps are usually fully saponified by the end of the cooking process, cold process soaps are also generally fully saponified within a day or two of making.
Cold-process soap making is also easier for most beginners due to the fluidity of the soap batter when poured into moulds. Hot processed soap batter is thicker and can have a flaky, gel-like texture which can be more difficult to handle. Hot processed soaps also require some kind of method for cooking the soap, usually a crockpot, slow cooker or double boiler on the stove, whereas cold process soap requires a simple plastic or stainless steel container for mixing the soap.
Both cold and hot processed soaps generally require a curing and drying period of 4-6 weeks after moulding to ensure the soap is as hard and dry as possible. Depending on the recipe used, some handmade soaps can be used after a slightly shorter cure period, and some benefit from a longer cure of around three months.
Ingredients and Equipment
To make your own cold-processed soap at home, you will need the following items:
Personal protective equipment – safety goggles that completely cover your eyes from splashes from any angle are ESSENTIAL through all stages of the soap making process. Rubber latex or nitrile plastic gloves are also important to protect your hands while mixing lye solutions and making soap batters. A respirator mask is also recommended when handling lye solutions. See my soap making safety essentials video for more information.
A small bucket, large jug or another container to mix your oils and soap in. Ideally, this would have at least three-litres capacity to accommodate most soap recipes. Make sure your container of choice has a pouring lip (for jugs), or a fine edge (for buckets) to ensure that your soap will pour cleanly without spilling down the side of the container. Polypropylene (no.5) plastic and stainless steel are the safest materials to mix your soap in.
An immersion or ‘stick’ blender to emulsify your soap batter. Budget department stores and charity shops sometimes have cheap stick blenders available that you can reserve for your soap making. It is ideal to have a separate blender for soap making and cooking purposes.
A digital kitchen scale for weighing your oils, water and sodium or potassium hydroxides. An accurate scale is essential. A 5kg kitchen scale is usually sufficient for the hobby soap maker, just ensure that your scale measures to the nearest gram.
A couple of spoons and/or spatulas (silicone spatulas are great) and a cheap whisk for stirring fragrance or essential oils into your soap and for scraping your soap batter out of the bucket or jug into the mould. Avoid using wooden spoons as they will be degraded by contact with lye. Stainless steel or silicone spoons are ideal. Never use aluminium utensils or containers for soap making.
Various smaller plastic containers for mixing your sodium hydroxide lye solution, weighing fragrances and mixing colours etc. Any plastic container with the number 5 recycling symbol is made of polypropylene and is heat resistant, safe for both soap batter and lye solutions and reusable.
Something to use as a soap mould – You will likely need containers or soap moulds of various sizes depending on the soap recipes you use or formulate for yourself. *See my soap tech videos for information about calculating your own soap recipes and getting them to fit your moulds perfectly.
You can use silicone muffin pans, silicone loaf pans, an old ice-cream container, Tetra pak milk cartons, old plastic lunch boxes or other food storage containers lined with non-stick baking paper or an old plastic bag. *Note that silicone moulds do not need to be lined, all other moulds (timber, hard plastic etc) will need to be lined. This is my neat method for making a folded soap mould liner for non-silicone moulds. This is my method for easily calculating the oils needed for a soap recipe for any sized or shaped mould.
Newspaper or plastic sheeting to cover your bench or kitchen counter. Raw soap batter, sodium and potassium hydroxides and liquid lye solutions are all highly corrosive and can damage some work surfaces (stainless steel benches do not need to be covered).
You will also need the basic ingredients for soap making:
Various oils, fats and butters - depending on your recipe of choice.
Sodium hydroxide (caustic soda) from online suppliers or your local supermarket/hardware (depending on your location). Make sure it is at least 98% pure sodium hydroxide and be aware that some drain cleaning products are made with a sodium hydroxide base but have other nasty fillers in them.
Potassium hydroxide for liquid or dual lye soaps, see this page for details of suppliers if you are in Australia.
Essential oils or fragrance oils for soap making – you can start out with eucalyptus or lavender oil purchased from the supermarket (in Australia), or purchase a wider variety of essential oils through the suppliers listed here if you are in Australia. Good quality fragrance oils and essential oils for soap making can be hard to source in some countries. Please check with manufacturers to ensure your products are safe for soap making and labelled accurately (they are what they say they are) before you use them.
Herbs, clays and colourants – you can make your soap as simple or extravagant as you like. Garden herbs and spices such as turmeric and paprika are simple and natural ways to add colour and interest to your first batches of soap.
Soap Making Safety
🔺 Sodium hydroxide and potassium hydroxide (lyes) used in soap making, in granular or flake form, or in solution with water/other liquids, as well as raw soap batter, are highly corrosive and require careful and attentive handling and the proper use of personal protective equipment.
You must protect your eyes at all times when handling lye in any form and throughout the soap making process.
Always refer to the Material Safety Data Sheet (MSDS) for your sodium hydroxide or potassium hydroxide products. Your supplier should be able to provide you with this information when you purchase these ingredients.
I’m sorry to sound like a broken record, but I highly recommend that you watch this video as it provides important essential information about the basics of soap making 👉
When making sodium or potassium hydroxide lye solutions for a soap recipe, ALWAYS pour the hydroxide beads or flakes slowly INTO THE WATER and NEVER THE OTHER WAY AROUND. If you pour water or other liquids onto dry sodium or potassium hydroxide granules, the mixture will generate a vigorous reaction which could include aggressive bubbling and spitting of the caustic lye solution into the air around the lye container (which you do not want!).
Always wear goggles that cover your eyes completely, and always pour the lye granules into the liquid and do this slowly and carefully every time. Cold water, ice cubes or other frozen liquids can also be used for making lye solutions, which greatly reduces fumes and the heat generated from the reaction of the hydroxides when they come into contact with water/other liquids.
Soap making is a fun hobby, but it needs to be taken seriously. Make sure you have fully researched your materials and methods before you start to make any soap recipe. Different ingredients and materials can have different effects that you may not anticipate.
Be safe, and have fun!