41Y/32M = 0 = grade 2?

[pau3]

I have a rather technical or maybe stupid question about
dichroic filter settings with variable contrast paper.

I have read in several places that dialing the same amount of
yellow and magenta in a color head has the same effect
of a neutral density filter and does change contrast. It only
changes the exposure.

However, the information provided by Ilford for their MGIV paper
says that one should dial 0 to obtain grade 2 with a single
filtration or dial 41Y/32M with a dual filtration, with and
enlarger using the Kodak CC system (like Omega or LPL).
But 41Y/32M is not the same amount of yellow and magenta.
How is it possible that both combinations yield the same
contrast (if they do)?

Note that I am not asking about enlarger differences or calibration.
I am only trying to understand why Ilford suggests using those
figures.

 

[sepiareverb]

Cyan can be used for ND- not terribly effective but possible. There are several schemes for a range of contrast divided into grades- each manufacturer has their own version, Agfa (? memory here) had their own version for various brands of colorheads.

The various mixes of M & Y filtration are approximations of filters- nothing is set in stone and I see students make the mistake of going from grade 2 1/2 to grade 3 and accidentally switching from an Ilford to a Kodak filter (or vice versa) and having wildly 'wrong' results. Use the filtration settings provided as a guide- nothing is set in stone here.

Years ago when I printed on graded paper the difference between Seagull G grade 2 and Ilford Galerie grade 3 was about zero.