Natures Garden

Elements Bath and Body
Soap Bar Qualities

FAQ number 4.  What are the best values for Hardness, Cleansing, Condition, Bubbly and Creamy?

The number ranges are meant to be a relative indicator of the soap's qualities and are general guidelines, not absolute standards. The numbers are based on the combined fatty acid content of your recipe (the "All" column) . Each fatty acid contributes certain qualities to the soap as shown in chart below.

 HardnessCleansingBubbly LatherCreamy LatherConditioning
PalmiticYes  Yes 
StearicYes  Yes 
Ricinoleic  YesYesYes
Oleic    Yes
Linoleic    Yes
Linolenic    Yes

The ranges of numbers below represent typical values.  They are suggested guidelines. As you gain experience, you will lean where you can color outside the lines so to speak.

Hardness - This refers to the hardness of the soap bar.  Higher is harder.  A range of 29 to 54 is satisfactory for this soap quality. A low Iodine value also contributes to hardness (see below).

Cleansing - This refers to the soap's ability to grab on to oils.  A soap molecule is a chain of carbon atoms. One end of the chain attracts water, the other end attracts oil.  When you wash your skin with soap and water, multiple chains will gather around a droplet of oil (which contains, for lack of a better word, dirt) with their oil-hungry ends attached to the oil droplet. The water hungry ends are surrounded with water. To make this happen you need to mix up (scrub or rub) the soap and water on your skin.  When you rinse, the oil droplets with the attached soap molecules are washed away.
more info here

Some soap molecules can have a very hungry oil grabbing end.  Soap made with too much Lauric and/or Myristic Acid can irritate the skin by washing away not only the top dirty layer of oils, but also the protective layer of surface oils on the skin.  Generally speaking, keeping the total of coconut and palm kernel in your recipe to no more than 30-35% is considered the norm.  However, when using large or very large percentages of coconut and palm kernel the strong cleansing can be compensated for by superfating with an oil or butter that has a high conditioning value.  A typical range for Cleansing would be 12 to 22.

Condition - Conditioning refers to the soap’s emollient content.  A soap’s emollients are left on the skin. They help the skin  retain moisture.  They sooth the skin and keep it soft.  A range of 44 to 69 is satisfactory for this soap quality.

Bubbly lather - This refers to the soap’s ability to lather up and get bubbly.  A typical range of values would be 14 to 46. The higher Bubbly numbers will tend to produce a foamy, fluffy lather rather than a creamy lather with littler or no bubbles.

Creamy lather - This value indicates the stability and creaminess of the lather.  Usually, increasing Bubbly will decrease Creamy and vice versa.  A range of 16 to 48 is common here. The higher Creamy numbers will tend to produce a creamy lather with lesser amounts of bubbles or foam. Soap made with oils that do not contain Lauric, Myristic or Ricinoleic acids will produce a soap with just creamy lather. An example would be 100% olive oil soap.

Iodine - As a general rule, the lower the number, the harder the bar and the less the conditioning qualities and vice versa.  A recipe with iodine values higher than 70 will tend to produce a somewhat soft bar of soap.  Definition: number of grams of iodine that will react with the double bonds in 100 grams of fats or oils.

INS - A measure of the physical qualities of the soap based on the SAP and iodine value. This value was introduced by Dr. Robert S. McDaniel in his wonderful book "Essentially Soap". The exact origin of the value is unclear but INS is derived from Iodine value and the SAP value; hence INS - "Iodine ’n SAP"  If the value is not in "Essentially Soap", it is estimated by subtracting the Iodine Value from the KOH SAP.  It is used to predict the physical characteristics of the soap bar - the ideal being 160.  Experience has proven a range of about 136 - 170 will gennerally be acceptable.

Summary of values:
Hardness29 to 54
Cleansing12 to 22
Condition44 to 69
Bubbly lather14 to 46
Creamy lather16 to 48
Iodine41 to 70 (lower = harder bar)
INS136 to 170 (higher = harder bar)

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