Theoretical Glaze Components?

[Benzine]

I've seen some recipes, list glaze ingredients as "Theoretical".  What does this mean?

Is this like Quantum Physics, and said ingredients may, or may not, exist depending on the point in time...

 

[High Bridge Pottery]

They are both amorphous and crystalline until you observe them 

 

I take it to mean the pure form of a feldspar would be theoretical but you are never actually getting pure feldspar out the ground.

 

 

[Benzine]

9 minutes ago, High Bridge Pottery said:

They are both amorphous and crystalline until you observe them 

 

I take it to mean the pure form of a feldspar would be theoretical but you are never actually getting pure feldspar out the ground.

 

 

That make sense, but I do like the philosophical ambiguity of a physical object being "theoretical".    "Theoretically" I have the money to pay my bills...

[Pieter Mostert]

Joel is right.

You've probably seen this in recipes that came from Glazy, which used to describe certain ingredients as theoretical, although this seems to have changed recently. The problem is that some recipes just call for something like 'potash feldspar' without specifying which brand. In order to work out the Seger formula for that recipe, you need to know (or make assumptions about) the composition of oxides in each ingredient. 'Theoretical' potash feldspar just meant that the composition of pure, i.e. "theoretical", potash feldspar was used to crunch the numbers.

In practice, think of it as a warning that your brand of potash feldspar (or whatever) may give different results than the brand used by the author of the recipe. (Also, don't trust the given Seger formula 100%)

[neilestrick]

For instance, the theoretical formula for feldspar is 1KNaO-1Al2O3-6SiO2, but it's never that orderly in real life, and there are other trace elements in there.