SOAP MANUFACTURING LIBRARY

Industry Knowledge

Soap is one of the oldest continuously made products in the world, and the market today runs from single-person craft studios to large personal-care manufacturers. Most commercial makers land in one of four methods: cold process, hot process, liquid soap and melt and pour. The method you choose decides almost everything else, from the equipment you need to how long product sits before you can sell it.

By the Numbers (2025)

The global soap market was worth about $50.7 billion in 2025 and is forecast to reach roughly $87 billion by 2034, a growth rate near 6.3% a year. Bar soap is the biggest single piece at about $32 billion, growing slower at around 4.6%. Liquid soap sits near $23 billion and grows faster, above 7% a year. The handmade and artisan segment is tiny by review, roughly $170 million in 2025, but it is growing about 6.7% a year, and online marketplaces are its fastest path to customers. The takeaway for an equipment buyer: bar methods are the volume base, liquid is the fast-growing lane, and small makers scaling online are the ones most likely to be outgrowing their pots.

Batch Variables That Change Your Equipment

Working volume in gallons, not bar count, is what sizes a tank. Operating temperature matters because cold process runs warm while hot process and liquid soap need a real cook. Viscosity at fill temp decides how the product moves through transfer and filling. And your ingredient mix, more solid fats or more liquid oils, changes how you melt and hold.

Cost and Time Realities

Cold and hot process bar soap has to cure, so plan rack and shelf space, not just production speed. Melt and pour skips the cure but leans on base cost. Liquid soap ties up a kettle during the cook. Lye, oils and fragrance are the recurring spend, and fragrance load is often the single biggest variable cost per batch.

Selling and Labeling

In the United States, most soap sold for cleaning is regulated as a consumer product, but the moment you make a cosmetic or drug claim, different rules apply. If you are scaling, get your labeling reviewed before you print thousands of them.

Questions to Answer Before You Buy

What is your largest working batch in gallons? What method and operating temperature? How viscous is the product when you fill? What are you filling into, molds, bottles or jars? What is your daily output goal, and where does the line slow down today? Answer those and the equipment choice gets simple.

Sources: global and bar soap figures, Fortune Business Insights (2025); liquid soap, Future Market Insights (2025); handmade soap, TechSci Research (2025). Figures update yearly; refresh before each annual review.

Industry Knowledge

The History & Development of Soap

Soap goes back at least four thousand years. Clay tablets from Babylon, dated around 2800 BC, describe boiling fats with ashes, which is the basic chemistry of soap. An Egyptian medical text, the Ebers Papyrus from around 1550 BC, describes combining animal and vegetable oils with alkaline salts to make a soap-like material used for washing and treating skin.

The familiar Roman story about "Mount Sapo," where rain washed animal fat and wood ash into a river and gave soap its name, is a popular legend. What is real is that by the later Roman world, soap was known and made across the Mediterranean and northern Europe.

The Craft Centers

Some of the oldest continuous soap traditions come from the eastern Mediterranean. Aleppo soap, made from olive oil and laurel oil, is one of the oldest hard soaps still produced. In Spain, Castile soap built its name on pure olive oil, and Marseille in France became a regulated soap center whose standards shaped European soapmaking for centuries.

The Chemistry That Industrialized It

Two breakthroughs turned soap from a craft into an industry. In 1791, Nicolas Leblanc developed a process to make soda ash from common salt, which gave makers a cheap, reliable alkali. In the 1820s, the French chemist Michel Eugene Chevreul explained the chemistry of fats and glycerin and showed exactly what happens during saponification. Later in the century, the Solvay process made soda ash cheaper still. Together these turned soap into an everyday product instead of a luxury.

Timeline based on well-documented history. The "Mount Sapo" origin is noted as legend.

Industry Knowledge

The History of Soap-Making Equipment

For most of soap's history the equipment was simple and the skill was in the hands. Makers boiled fats and alkali in open cauldrons over fire, stirred by hand or with paddles, judged the batch by eye and feel, then poured it into wooden frames to set and cut. It worked, but it was slow, hot, inconsistent and hard to scale.

From Open Kettles to Controlled Heat

The first real jump was controlled, even heat. Instead of a fire under a pot, makers moved to heated and jacketed tanks that hold a set temperature, so a batch behaves the same way every time. That single change, repeatable temperature, is what lets a small maker turn a recipe into a product.

Mixing, Tilting and Transfer

Next came equipment that removed the heavy, dangerous manual steps. Mixing and tilting kettles let you heat, blend and then tip the batch out without lifting a scalding pot. Heated transfer systems move hot or viscous soap between vessels and to the fill point without carrying pitchers. Dedicated lye equipment made caustic prep safer and more consistent.

Integrated Systems

The modern step is treating the whole line as one heated flow: melt, hold, mix, transfer and fill, all kept at temperature so the product never sets up in the wrong place. That is the same logic behind our PRIMO systems on the candle side, applied to soap. The goal has not changed in four thousand years, consistent soap made safely. The equipment just finally caught up to it.

Industry Knowledge

Soap Types, Oils, Lye, Fragrance & Colorants

Four methods cover most of what people make. Knowing which one you run tells you what equipment you need, so start here.

The Four Methods

Cold process blends heated oils with lye solution, brings it to "trace," then pours to mold. No cook, but it cures four to six weeks. Hot process is the same start, then you cook the batch with heat to finish saponification faster, so it is usable sooner. Liquid soap uses potassium hydroxide instead of the sodium hydroxide used for bars, cooks to a paste, then dilutes and bottles. Melt and pour skips lye entirely: you melt a ready-made base, add color and scent, and pour. Fastest to sell, most limited to customize.

Oils and Fats

Solid fats like coconut, palm and tallow give hardness and lather. Liquid oils like olive, sunflower and castor give mildness and conditioning. Every oil has its own saponification value, which is how much lye it needs, so changing your oil blend changes your lye amount.

Lye: NaOH or KOH

This is the distinction that trips people up. Sodium hydroxide (NaOH) makes hard bar soap and is used for cold and hot process. Potassium hydroxide (KOH) makes soft and liquid soap. Superfatting means using slightly less lye than the oils could consume, leaving a small amount of unreacted oil for a milder bar. Lye is caustic and demands proper handling equipment and safety gear, whichever type you use.

Fragrance and Color

Fragrance and essential oils are added at specific temperatures, and some fragrances accelerate trace or discolor over time, which affects how fast you have to move a batch. Colorants range from natural clays and botanicals to micas and pigments. Both behave differently in a hot cook than in a cool pour, which is one more reason your method drives your process.