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§ 16

Cream recipe: phases' weight

How many grams of each phase should I weigh out for my cream?

Answer: A cream recipe is written as a percentage of the finished amount: so much fat phase, so much emulsifier, so much active substance and preservative, and the rest is water phase. When you mix a portion at the clinic or school, the percentages must be converted to grams. The calculator works out each phase and finds the water phase as what is left up to 100%. You take the dosing of emulsifier and preservative from the manufacturer's datasheet. The calculator invents no doses.

Formula

Gram af en fase = færdig mængde × fasens procent ÷ 100

Vandfase = 100 % − fedtfase − emulgator − aktivstoffer − konservering (opskriften skal give 100 %)

If the water phase fraction is negative, the recipe is over 100%, and the percentages must be corrected

Symbols and units in the formula
SymbolMeaningUnit
batch_gFinished amount creamg
fedtfase_pctFat phase (oils, butter, wax)%
emulgator_pctEmulsifier (per manufacturer's instructions)%
aktiv_pctActive ingredients and additives (e.g. glycerine, extracts)%
konserv_pctPreservative (according to manufacturer's instructions)%
=Water phase (water, hydrolat)g
=Fat phaseg
=Emulsifierg
=Active ingredients and additivesg
=Preservativeg
=Water phase's share of the recipe%

Validity and source

Source
Competence objective: homogeneous mixtures and fats in skincare · percentage calculation

Does not apply when

  • Preservatives can only be used if they are listed in Annex V of the EU Cosmetics Regulation (1223/2009) and at most in the concentration stated there and in the product's datasheet. A cream for sale requires a safety assessment under the regulation.

Worked example

The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.

Substituted

  • Finished amount cream200 g
  • Fat phase (oils, butter, wax)20 %
  • Emulsifier (per manufacturer's instructions)5 %
  • Active ingredients and additives (e.g. glycerine, extracts)5 %
  • Preservative (according to manufacturer's instructions)1 %

Giver

  • Water phase (water, hydrolat)138.0 g
  • Fat phase40.0 g
  • Emulsifier10.0 g
  • Active ingredients and additives10.0 g
  • Preservative2.00 g
  • Water phase's share of the recipe69.0 %

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Sådan bruger du den

Når du laver en creme i undervisningen eller rører en grundcreme til klinikken, står opskriften i procent. Du skal vide, hvor mange gram af hver fase du skal veje af. Beregneren regner fedtfase, emulgator, aktivstoffer og konservering om til gram og finder vandfasen som resten op til 100 %.

Step by step

  1. Bestem hvor mange gram færdig creme du skal lave.
  2. Skriv opskriftens procenter for fedtfase, emulgator, aktivstoffer og konservering.
  3. Gang den færdige mængde med hver procent og del med 100.
  4. Vandfasen er det, der mangler op til 100 %. Er den negativ, er opskriften over 100 %.
  5. Vej faserne af hver for sig, og bland efter opskriftens metode, fx ved samme temperatur.

Typical errors

  • At glemme at procenterne skal give 100. Lægger du et aktivstof til uden at tage det fra vandfasen, bliver cremen forkert.
  • At veje små mængder som konservering på en køkkenvægt. Brug en vægt, der vejer på 0,01 g.
  • At finde selv på doseringen af konserveringsmiddel. Den skal komme fra producentens datablad og må ikke overstige grænsen i kosmetikforordningen.

Examples from everyday life

Let dagcreme

Du laver 200 g let dagcreme med 20 % fedtfase, 5 % emulgator, 5 % glycerin og ekstrakter og 1 % konservering efter producentens anvisning.

Finished amount cream
200 g
Fat phase (oils, butter, wax)
20 %
Emulsifier (per manufacturer's instructions)
5 %
Active ingredients and additives (e.g. glycerine, extracts)
5 %
Preservative (according to manufacturer's instructions)
1 %

It means: Vej 138 g vandfase, 40 g fedtfase, 10 g emulgator, 10 g aktivstoffer og 2 g konservering af. Vandfasen er 69 % af opskriften.

Fed natcreme til tør hud

Til tør vinterhud laver du 100 g natcreme med 35 % fedtfase, 6 % emulgator, 3 % aktivstoffer og 0,8 % konservering.

Finished amount cream
100 g
Fat phase (oils, butter, wax)
35 %
Emulsifier (per manufacturer's instructions)
6 %
Active ingredients and additives (e.g. glycerine, extracts)
3 %
Preservative (according to manufacturer's instructions)
0.8 %

It means: Du skal bruge 35 g fedtfase og 55.2 g vandfase, svarende til en vandfase på 55.2 %. Emulgatoren er 6 g og konserveringen 0.8 g. Vej konserveringen på en finvægt.

Rule of thumb

Let creme: ca. 15-25 % fedtfase. Fed creme: ca. 30-40 % fedtfase. Resten er mest vand.

How to check the answer

Alle faserne i gram skal tilsammen give den færdige mængde.