Soap 101: The Only Guide You’ll Ever Need

There’s something in your bathroom that you may not give much thought to… but you really should! Yep, we’re talking about that bar of soap hanging out by the sink or shower. The pleasure of using a finely-crafted soap is one of life’s little luxuries! When you really delve into the world of soap, you’ll discover there are a surprising amount of varieties with different benefits. We carry an extensive collection of soaps from around the world, and often get questions about their ingredients, how long they’ll last, and which ones are best for which skin types. So, we decided to create a soap tutorial to explain various terms and help you discover your new favorite soaps!

What is Soap?

Soap is made by combining oil or fat with an alkaline solution, which induces saponification. Using a different alkaline solution results in a different type of soap. For example, soaps made with sodium hydroxide tend to be firm, like Saponificio Varesino, while soaps made with potassium hydroxide yield a soft or liquid soap, like Dr. Bronner’s. Each oil or fat has a distinctive fatty acid content which results in soaps with different textures, lather, and skin benefits, which we’ll investigate further.

Soap-Making Techniques

There are two main ways to make soap: the hot-process method and the cold-process method. In the hot process method, the oil or fat and the alkaline solution are mixed together and heated to speed up the saponification process. Hot-processed soaps can go through additional steps to remove impurities and create a more uniform bar. Preferred by most small-batch soap-makers, the cold process method warms the oil or fat and mixes it well with a lye solution. The mixture is poured into molds and continues the saponification process for 12 to 48 hours. Cold-processed soaps are usually cured for an additional 2-6 weeks.

Types of Soap

Vegetable-Based

Vegans, vegetarians and others concerned about avoiding animal ingredients should use vegetable-based soaps. We mentioned above that each oil has a unique fatty acid content, which will result in a different performance and distinctive skin benefits. Coconut oil yields soap with lots of suds, but it can be drying, so an additional moisturizer is usually added. Shea and cocoa butters give soap a rich, luxurious feel and offer skin extra hydration. Both almond oil and apricot kernel oil have a lighter viscosity which absorbs easily into skin and leave it exceptionally soft. Extremely popular with soap-makers, olive oil makes hard, long-lasting soaps that are mild with a low lather. Vitamin-rich, avocado oil has a heavier feel that creates a richer bar of soap. Kala’s Avocado Soap is nourishing for both face and body.

Tallow-Based

Tallow is a form of animal fat that has been used to make soap for thousands of years (you can even find ancient Egyptian tallow soap recipes!). It tends to give soap a creamy lather, while offering extra conditioning and hydration for the skin. Tallow became less popular as many people started to avoid products with animal ingredients. These days, it’s making a comeback, particularly in shaving soaps; fans say they offer a superior, rich lather and better cushion for a fantastic shave. The Formula T line by Wet Shaving Products is particularly popular within the shaving community.

Triple-Milled Soap

This type of soap goes by a few different names: triple-milled, hard-milled, and French-milled. After the saponification process, the soap is passed through high pressure rollers at least three times. All the ingredients are thoroughly mixed and excess water and air is pressed out of the mixture, creating a fine, smooth paste. The resulting hard soap has a luxurious, refined consistency and is extremely long-lasting. Mistral makes triple-milled soap with lovely scents and exquisite packaging—perfect for gifts!

Marseille and Castile Soap

Traditionally made with a high olive oil content, these soaps are extra mild on the skin. Marseille Soap has been crafted since the 1300s with a mixture of sea water, at least 72% olive oil, soda ash, and lye. This formula creates a hard, long-lasting bar of soap with a light lather (it can also be adjusted to produce a mild liquid soap). Though it can be made in a bar, Castile Soap is most popular in its liquid form. Originally crafted by the early soap-makers of Europe with 100% olive oil, nowadays it can be made from other oils. Castile soap is favored to due its versatility—you can use it to wash your hands and clean the stove! Dr. Bronner’s is probably the best known castile soap in the U.S.

Glycerin Soap

A component of oil or fat, glycerin is a naturally occurring byproduct of saponification. To create Glycerin Soaps, additional alcohol and/or sugar are used during the soap-making process. This aligns the soap molecules, giving the soap a distinctive clear look. Glycerin soap doesn’t offer much lather or last as long as other types of soap. However, it is mild and hydrating, making it a good choice for those with skin sensitivities.

Milk Soap

During the soap-making process, milk is used instead of (or in addition to) water, which yields an extra creamy bar. Milk Soap has additional vitamins which make it especially nourishing for sensitive and dry skin. Chivas Skin Care makes excellent soaps with fresh goat’s milk from the family farm.

Black Soap

Originating in West Africa, African Black Soap is crafted from the ash of local plants, such as plantain skins, shea tree bark, and cocoa pods. It can be made into a bar or liquid, and has been found to have antifungal properties. Featuring a high content of pure olive oil and pulp, Moroccan Black Soap has a very unique gel-like texture. Rich in vitamin E, it is extremely hydrating and leaves skin noticeably supple. We’re big fans of Zakia’s Morocco’s authentic formula.

Charcoal Soap

Charcoal has been used for thousands of years to purify and detoxify. Charcoal is extremely porous—due to this unique molecular structure, impurities are drawn out into these pores. When used in soap, it provides deep cleansing without over-drying. Charcoal Soap is especially popular among folks with oily or blemish-prone skin. We love this Chidoriya version made with bamboo charcoal from Japan.

Pine Tar Soap

Created by burning pine wood, Pine tar is a sticky substance that has been used over the centuries for everything from weather-proofing nautical rope, to coating baseball bats, to eradicating dandruff! Pine Tar Soap is commonly used to soothe and treat skin conditions like eczema and psoriasis. It does have a very particular smell, so you may want to give it a sniff before buying! The Grandpa Soap Co. has been making this classic soap since 1878.

We hope our tutorial helped guide you on your sudsy journey towards soap nirvana! Don’t forget to check out our curated selection of amazing soaps from around the world.