Even among papers offered by Harman the different VC papers have different nuances, which one
just has to learn by experience. But if one is going to jump into the pool in the first place, it's easiest
to teach simple Blue versus Green tricolor, or basic Magenta versus Yellow variable filtration. Once
these basics are understood, then the more complex interactions of the actual paper engineering can
be fine-tuned, like adjusting the water temperature after you dive in. It's a lot easier to demonstate
on test strips than it is to explain. No need to make a religion out of any single method.