Soap Bar Properties Explained

When using a soap calculator like Soaply, you'll see property predictions for your recipe. But what do these numbers actually mean? Let's break down each property.

How Properties Are Calculated

Soap properties are predicted using the fatty acid profile of your oils. Each oil contains different fatty acids (lauric, myristic, oleic, etc.), and each fatty acid contributes to specific properties.

The Properties

Hardness (29-54 ideal)

What it means: How solid and long-lasting your bar will be.

Affected by:

• Lauric acid (coconut, babassu)
• Myristic acid (coconut, palm kernel)
• Stearic acid (cocoa butter, tallow)
• Palmitic acid (palm, lard)

Tips:

• Below 29: Bar will be soft, may not last long
• Above 54: Bar may be brittle or crack
• Cure time also affects hardness

Cleansing (12-22 ideal)

What it means: How effectively soap removes oils and dirt from skin.

Affected by:

• Lauric acid (primary contributor)
• Myristic acid

Tips:

• Below 12: May not cleanse effectively
• Above 22: Can strip natural oils, feel drying
• Balance with conditioning for best results

Conditioning (44-69 ideal)

What it means: How moisturizing and gentle the soap feels.

Affected by:

• Oleic acid (olive, avocado)
• Ricinoleic acid (castor)
• Linoleic acid (sunflower, hemp)

Tips:

• Higher = more moisturizing
• Helps counteract high cleansing
• Important for sensitive skin formulas

Bubbly Lather (14-46 ideal)

What it means: How much big, fluffy bubbles your soap produces.

Affected by:

• Lauric acid (coconut, babassu)
• Ricinoleic acid (castor)

Tips:

• Coconut oil is the bubble king
• Castor oil stabilizes bubbles
• Hard water reduces lather

Creamy Lather (16-48 ideal)

What it means: Dense, lotion-like lather vs thin/watery.

Affected by:

• Oleic acid
• Stearic acid
• Ricinoleic acid

Tips:

• Olive oil creates creamy lather
• Complements bubbly lather
• Many people prefer creamy

INS Value (136-170 ideal)

What it means: Overall quality indicator developed by Dr. Robert McDaniel.

Calculated as:
INS = Iodine Value + (SAP × 100)

Tips:

• 136-170: Well-balanced soap
• Below 136: May be soft or sticky
• Above 170: May be hard or drying

Reading Your Recipe's Properties

When you build a recipe in Soaply, the calculator shows each property with:

• Current value
• Ideal range (shown in color)
• Warning if outside recommended range

Green = Good

Your property is within the ideal range.

Yellow = Caution

Slightly outside ideal - may still work fine.

Red = Warning

Far outside ideal - consider adjusting your recipe.

Balancing Properties

Properties often compete with each other:

High Cleansing	vs	High Conditioning
----------------	---	-------------------
More lauric acid	More oleic acid
Drying	Moisturizing

The art of soap making is finding your perfect balance!

Example Trade-offs

Facial Soap:

• Lower cleansing (10-15)
• Higher conditioning (55-70)
• Creamy lather preferred

Kitchen/Utility Soap:

• Higher cleansing (18-25)
• Lower conditioning okay
• Lots of bubbles helpful

Baby/Sensitive Skin:

• Low cleansing (10-14)
• High conditioning (60+)
• Gentle everything

Using Properties Effectively

1. Start with a goal - What kind of soap do you want?
2. Build your recipe - Add oils while watching properties
3. Adjust as needed - Swap oils to move properties
4. Check warnings - Our calculator will flag imbalances
5. Test and iterate - Properties are predictions; always test!

Beyond the Numbers

Remember: property predictions are just estimates based on fatty acid profiles. Other factors affect your final soap:

• Cure time - Longer cure = harder bar
• Superfat - Higher superfat = more conditioning feel
• Additives - Sugar adds bubbles, salt hardens
• Water hardness - Affects lather
• Fragrance - Some accelerate trace

Use properties as a guide, not gospel. Your best soap comes from experience and testing!

Try It Now

Head to our Soaply calculator and experiment with different oils. Watch how adding coconut increases cleansing while olive boosts conditioning. Finding that perfect balance is part of the fun!

Keep Learning

• Best Oils for Soap Making - Deep dive into each oil's properties
• Complete Guide to Superfat - How superfat affects your bar's feel
• Troubleshooting Failed Batches - Fix common problems

💬 Frequently Asked Questions

What is a good INS value for soap?

The ideal INS value ranges from 136 to 170. Bars in this range tend to be well-balanced with good hardness, lather, and conditioning. Values below 136 may produce soft or sticky bars, while values above 170 can result in hard, drying soap.

How do I make my soap bar harder?

Increase the percentage of hard oils like coconut oil, palm oil, cocoa butter, or tallow. You can also use a higher lye concentration to reduce water, which helps bars firm up faster. Adding sodium lactate at 1 tsp per pound of oils also helps.

Why is my soap not lathering well?

Low lather usually means your recipe doesn't have enough lauric acid (from coconut or babassu oil) or ricinoleic acid (from castor oil). Try adding 5-8% castor oil and keeping coconut oil at 20-25% for a good lather boost.

Can soap be too conditioning?

Very high conditioning values (above 70) can mean softer bars that don't last as long and may feel oily rather than clean. If you're selling soap, aim for 44-69 on the conditioning scale for the best customer experience.