First, Hunter, while creating a template that I used for the design of the book, suggested the Pantone Warm Gray Number 8 as the second ink, having used it with great success in a catalog that he had done previously

Notes on Printing for Alone in a Crowd
Jim Kasson

I printed 1000 copies of this catalog. My cost was $5600, or $5.60 each. A little less than a thousand dollars was for imagesetter film and plates, and the rest was for paper, ink, and press time. The cover is 100 pound glossy cover stock, and the interior pages are 80 pound glossy. The cover images were varnished for durability. I made the duotones in Photoshop, imported the images into InDesign, added the copy and burned a CD which I handed to the printer. The signatures were 11x17. The InDesign file was set up for 8½x11 pages, and the printer did the imposition. Using the small signatures meant that the press operator only had to deal with the images two at a time, and could optimize the quality with few tradeoffs. The press operator was an accomplished photographer and a superb printer, and his judgment undoubtedly improved the quality of the finished product.

This catalog is printed as a duotone, with black and Pantone Warm Gray Number 8. The duotone curves came from Stephen Johnson, and are distributed with Photoshop. The one I used is called WG8-2. I wanted to have fine detail in Zones VI ½ through VIII without having the halftone screen in that tonal range be obvious, even though the press was limited to a 200-line screen. Warm Gray Number 8 looks about Zone V when used 100% all by itself. So I wanted a duotone curve that used a lot of Warm Gray Number 8 in the Zone VI 1/2 to Zone VIII region, figuring that using the weaker ink would result in greater dot size, and therefore less dot visibility (The dots that seem to stand out for me in the highlights are the little tiny ones with a lot of white around them.) Stephen's Warm Gray Number 8 curve uses a lot of the secondary ink in the highlights and not much black, backing off on the secondary ink in the shadow areas (mostly because itÕs almost 100% by Zone IV), which is what I wanted.

Let's look at the curves and see how they fulfill my objectives. As a rule of thumb, in Gray Gamma 2.2 color space, one zone is about 12.5%, so in the curves below, Zone IX is in the lower left corner of the curve, and Zone I is in the upper right corner.

Here's what you see when you first open up the duotone in Photoshop.

If you double-click on the curve for Warm Gray #8, you see the following. Note the rapid buildup of ink until about Zone V, where the curve flattens quite dramatically.

If you double-click on the curve for the black ink, you see the following. There is hardly any black ink in the highest three zones, and then the curve slopes upward, becoming fairly linear by Zone IV. Thus the shadow separation is performed almost entirely by the black ink.