This is a method of deriving the oxide amounts from a glaze recipe. It uses the relative weights of all the atoms that are in the fired glaze and organises how many there are of each sort relative to one another. It is important to note that the molecular formula is an abstraction that is based on what actually happens. So in a molecular formula it is common to talk about fractions of molecules, when in reality that isn't the case, but the important information isn't about the absolute numbers of molecules in a glaze (which would be countless billions) but rather the relative numbers of each.

To start the process, first list the ingredients:
(for our example we will be using the Leach Limestone glaze)

Next we find the list of oxides that makes up each ingredient and what it's molecular weight is. Molecular weight isn't an actual physical weight, instead all the atoms are ranked from lightest (hydrogen) to the heaviest (ununbium), hydrogen was given the molecular weight of 1 and the weights of all the other elements are expressed in terms of their relationship to the weight of the hydrogen atom. For example the atom oxygen is sixteen times as heavy as hydrogen so its' atomic weight is 16. The molecular weight of a material is just the sum of all the atomic weights that make up the material's formula. So for a material like china clay with the formula; Al2O3.2SiO2.2H2O the weights are added up like this;
Al = 27 X 2 = 54
O = 16 X 3 = 48
Si = 28.1 X 2 = 56.2
O = 16 X 4 = 64
H = 1 X 4 = 4
O = 16 X 2 = 32
Total = 258.2
The attached sheet lists all the common elements used and the molecular weights for all the common materials used in glazes.
Now we layout the glaze recipe using the above information: