So, back to square one, aren't I? I'm at the "this is what salt is used for" point, using the gastronomic metaphor. I need to look at the basic of maths as it applied to nodes. Which I've started doing with the simple adding of colours. Subtracting required a bit more understanding of what values mean to Poser. Applying an "average function" was obvious to you because you prove unknowns with knowns. I've got to get to the point where I would naturally reach for that sort of function to solve a problem.

Now, I'm going to have a look at your candle shader...

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks