Cosmetic Chemistry: What Does QS Mean in a Cosmetic Formula?

 

When I just started learning how to read a cosmetic formula, there is one abbreviation that I often encounter – q.s. which stands for the Latin word quantum satis that literally translates to “as much as is enough”. When applied to a specific ingredient in a cosmetic formula, q.s. essentially means “add as much of this ingredient as is needed to achieve the desired result, but not more” (source: Wikipedia). You will often see q.s. as quantity indicator for cosmetic ingredients that may vary in amount depending on the formulator’s preference such as preservative, fragrance and colorant.

In the sample cosmetic formula below, both the preservative and pH adjuster are indicated as q.s. as their quantity. Different preservatives have different usage rate, so q.s. in this case simply means “to add the recommended amount depending on the preservative you are using”. In the case of pH adjuster (e.g. citric acid or sodium hydroxide solution), the amount needed also varies depending on the final pH of your formula, thus the need for it to be specified as q.s. in the formula.

Formula: Aloe Vera Face Toner

(Makes 100 grams)

Ingredient	Weight (%)	Weight (g)
Phase A
Water	to 100	to 100
Aloe Vera Extract (liquid)	20	20
Glycerin	3	3
Phase B
Preservative (water soluble)	q.s.	q.s.
Phase C
pH Adjuster	q.s.	q.s.
	100	100

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