There is a dedicated chapter in ***Way Beyond Monochrome*** that explains the
procedure to match precise grades with a color head:
[http://www.waybeyondmonochrome.com/WBM/TOC.html](http://www.waybeyondmonochrome.com/WBM/TOC.html)
Some chapters were available on this site in the past, including the one that
interests us but, unfortunately, this no more the case.
Searching the web, I found it on another site (extracted from the first edition
of the book):
[http://babardestcyr.free.fr/CntrstCtrlClrEnlargers.pdf](http://babardestcyr.free.fr/CntrstCtrlClrEnlargers.pdf)
Anyhow, this book has a lot more than this and is an absolute must have ...
Ilford has a documentation on its Multigrade paper and color filtration tables
through 2 methods:
- single filtration - only one color at a time, from yellow to magenta, to
achieve all grades. Exposure varies from one grade to the other.
- double filtration - using a variable mix of yellow and magenta to achieve
most of the grades but keeping exposure constant between the grades.
[https://www.ilfordphoto.com/wp/wp-content/uploads/2017/03/Contrast-control-for-Ilford-Multigrade.pdf](https://www.ilfordphoto.com/wp/wp-content/uploads/2017/03/Contrast-control-for-Ilford-Multigrade.pdf)
As you indicated, Paul Butzi also wrote something on the topic but his former
website (butzi.net) does not seem available anymore.
The article is still available here:
[http://fliphtml5.com/exru/vhtf/basic](http://fliphtml5.com/exru/vhtf/basic)
Claudio Bonavolta
www.bonavolta.ch
Here's something that contains good information, including data for a DeVere
colour head:
[http://phototechmag.com/a-better-choice-than-vc-filters/](http://phototechmag.com/a-better-choice-than-vc-filters/)
As you can see, the primary adjustments are to the Yellow and Magenta
filtration. The Butzi (?) article explained a way of keeping the exposure
times uniform. (It was something equivalent to adding or subtracting
VC-neutral-density filtration.)
