Coconut Oil in Soap: Guide and Recipes

TL;DR: Coconut oil adds hardness and foam - but only in the right amount (25-35%) with the corresponding super fat. Above 40% without super fat, the soap dries out. For 100% coconut soap, 20% super fat is required.

Coconut oil is the most commonly used oil in home soap making - and for very specific reasons. It adds a hardness, lather and cleaning power that other oils simply cannot provide to the same degree. But it can also be overdosed, resulting in a soap that dries out the skin more than rainwater after a bath.

This page will tell you how coconut oil in soap works, why it's so popular, how to dose it correctly and what happens when you make it into a 100% recipe.

Why coconut oil belongs in (almost) every recipe

Lauric acid: the foundation of everything

Coconut oil contains approximately 48-52 % lauric acid (lauric acid, C12:0). It is a short-chain saturated fatty acid and is responsible for three key properties of coconut soap:

Hardness. Sodium laurate crystallizes rapidly and forms a solid structure. Soap with a good coconut oil content is hard when removed from the mould - unlike pure olive soap, which tends to be soft for weeks.

Big, thick bubbles. Lauric acid produces a big, fast lather - the type that most people associate with "proper soap“. Olive or sunflower oil alone produces a fine, creamy lather, but without significant bubbles.

Cleaning power. Shorter chain fatty acids are more effective in removing dirt and grease. Coconut soap cleans well. However, too much coconut can clean too much - and thus remove natural skin oils.

Myristic and caprylic acid

Coconut oil also contains 18-20 % myristic acid (myristic acid, C14:0), which adds foaming and hardness, and small proportions of caprylic and capric acids (C8, C10), which further contribute to the cleaning properties.

How much coconut oil to add to a recipe?

The correct dosage determines the quality of the soap. This is the most common question and the answer depends on the purpose of the soap:

15-20 % - minimum for a good contribution to foam and hardness. Suitable for very mild soaps (for babies, sensitive skin). Soap will be less hard and lather less dramatic.

25–30% - standard amount in recipes for normal skin. Optimal balance between lather, hardness and gentleness. This is where most recipes start.

35-40 % - A stronger cleansing soap, suitable for normal to oily skin or as a hand soap. Super fat is important here (5-8%).

50-65 % - distinctive cleaning soaps, laundry bars, camper soaps. Super fat required (20% for 100% coconut soap).

The golden rule: The more coconut oil, the higher the super fat you need to keep the soap from becoming drying.

What is superfat and why is it essential?

Super fat (overfatting) is the deliberate addition of slightly less lye than would be needed for 100% saponification of all oils. This leaves some of the oils unsaponified and creates a conditioning layer in the finished soap.

• For recipes with 30% coconut oil: super fat 5% is standard
• For recipes with 50%+ coconut oil: super fat 8-10%
• For 100% coconut soap: super fat 15-20%

100% coconut oil soap: when does it make sense?

At first glance, 100% coconut soap sounds like a recipe for disaster - after all, coconut is drying. But it's actually an interesting and functional soap if formulated correctly.

The key is in the super fat 20%: With such a high overflow, a large amount of unsaponified coconut oil remains in the soap, which conditions. The resulting soap is hard, produces a dramatic lather and yet conditions - because unsaponified coconut oil does not dry.

When to use 100% coconut soap:

Laundry bar (laundry soap): With zero or minimal overflow (0-3% SF), 100% coconut soap is excellent for hand washing. It cleans powerfully, does not form deposits and is ideal for delicate baby gear.

Camping soap: It works even in salt water - a unique feature that other soaps can't do. Sea water breaks down other soaps (sodium salts are soluble in salt water), but sodium laureate is more resistant.

Hard soap for the workshop: Mechanicslike hand cleansing soap - add pumice or coffee grounds for exfoliation, no super fat.

Recipe: 100% coconut soap (laundry/camping bar)

Ingredients:

• 700 g coconut oil (RBD - refined, unscented)
• For SF 20%: 97.3 g NaOH + 233 g water
• For SF 0 %: 121.6 g NaOH + 292 g water

Saponification number of coconut oil: 0.178 (NaOH). For 700 g: 700 × 0.178 = 124.6 g NaOH for 0% SF. With 20% SF: 124.6 × 0.80 = 99.7 g NaOH.

Procedure: Same as the standard cold process. Note: 100% coconut soap trace is achieved very quickly (2-5 minutes with a stick blender). Add ingredients quickly or prepare them in advance. The soap will be hard after 24 hours and can be cut.

Coconut oil as a palm oil replacement

Palm oil is a controversial topic in the domestic soap industry. Traditionally, it is used for hardness and for a stable medium-large lather. A palm oil-free alternative requires replacing its function in another way.

Coconut oil can provide hardness, but it does not create the same type of foam as palm. A better substitute is a combination:

• Coconut oil (25-30%) - for hardness and large bubbles
• Cocoa butter or shea butter (10-15 %) - for hardness and conditioning
• Tallow or hydrogenated castor oil - for foam stability

A typical palm-free recipe looks like this:

• 30% coconut oil
• 15 % cocoa butter or shea butter
• 10% castor oil (for foam)
• 45 % olive or sunflower oil

The result: a hard soap with good lather and conditioning properties, without palm oil.

Which coconut oil to buy for soap making?

RBD vs. extra virgin

RBD coconut oil (Refined, Bleached, Deodorized) is ideal for soap making. It has no fragrance, so there are no conflicts with perfume or essential oils. It is cheaper. The properties for soap are identical to virgin oil - the saponification number is the same.

Extra virgin coconut oil is quite functional, but brings a natural coconut scent that may clash with other scents. For natural "coconut soaps&#8220with no added fragrance&#8220this is an advantage in contrast.

Where to buy

• Dm, Rossmann, Tesco: regular virgin coconut oil in cups of 400-500 g. Price 80-130 CZK for 400 g. Functional, but expensive for larger batches.
• E-shops focused on soap making (see Suppliers in the Czech Republic and EU): RBD coconut oil in packs of 1-5 kg for 80-150 CZK/kg.
• Rohlik.cz, Kosik.cz: virgin coconut oil 1 kg for 150-200 CZK.
• Macro, Metro: large packs for those who produce regularly.

For the occasional soapmaker (1-2 batches per month), supermarket coconut oil is perfectly affordable. For regular production, it is worth buying a kg pack from the e-shop.

Melting point: 24 °C

Coconut oil solidifies below 24 °C. In a cold kitchen (cold, air conditioning) you will need to melt it - just a water bath or microwave for 30 seconds. In summer it can be liquid right in the jar - this is normal, it does not affect the quality.

Frequently asked questions

Can I use cooking (food grade) coconut oil? Yes, no problem. Food grade coconut oil, virgin or RBD, works in soap just like "cosmetic“. There is no difference in the saponification number or the resulting soap.

Why does my coconut oil soap cut poorly? 100% or high percentage coconut soaps are very hard and brittle. Slice as soon as possible after removing from the mold (24-36 hours) - they may crumble later. Or use a silicone mold for individual pieces.

The coconut oil has melted but quickly solidifies back - what to do? Temper the oils together. Once the coconut oil is melted, add the other liquid oils - the resulting mixture has a lower freezing point and will remain liquid even at room temperature. Stir the lye solution with the oils as soon as possible after tempering.

My coconut oil soap is cracking on the surface. Causes: mixing too hot (lower the temperature of the oils below 40 °C), too fast trace with an aggressive gel phase, or over-soaping. Deep cracks indicate overheating - next time don't pack the mould into the blankets (let the gel phase run more slowly).

How much super fat do I need for 35% coconut soap? The standard is 5-7%. For very mild soap 8-10%. Without super fat the soap will be drying, with too much SF it will be soft and greasy.

Is 100% coconut oil soap suitable for skin? Not without super fat. With 20% super fat, yes - the conditioning oil compensates for the cleansing power of lauric acid. But it's still a soap more for shaving or washing than for sensitive skin.

See also:

• Oil and fat encyclopedia - comparison of all oils and their properties
• Recipes for beginners - proven first recipes with coconut oil
• Soap calculator - Calculate the amount of NaOH for your recipe
• Palm-free formulation - how to replace palm oil