MIS's "Eboni" inksets are 100% carbon. MIS PK, LK, and LLK are also 100% carbon. I believe Jon Cone's carbon sepia is also 100% carbon. All of the other B&W inksets and the OEM LK and LLK inks have color pigments blended into the carbon. It can take approximately 50% color pigment to 50% glossy carbon to make a neutral gray ink.
See
http://www.aardenburg-imaging.com/ for the lightfastness tests of Eboni and Carbon Sepia.
Although I have not updated it recently, page 2 of
http://www.paulroark.com/BW-Info/Eboni-6.pdf has some delta-e numbers from these tests that give a quick comparison of inksets.
Eboni is unique in that it is the most neutral of the carbon inksets. (Bob Zeiss, founder of MIS, and I spent a lot of time looking for and testing carbon pigments to find the one that gave the best dmax and was relatively cool/neutral.) At page 10 of
http://www.paulroark.com/BW-Info/Eboni-6.pdf I have a graph of the Lab B values for Eboni-6 on Epson Hot Press Natural, one of the most neutral-printing papers. Lab B values measure the warmth of carbon most clearly. At the low end, Epson Hot Press will hold the increase in Lab B from the paper white to the maximum value to about 1.5. Many papers are in the range of an increase of 4 to 5. MIS PK, LK, and LLK as well as Cone carbon sepia have increases on matte paper of about 8. Carbon on glossy paper can reach a Lab B value increase of 14.
When we judge the warmth of a print, our eyes will use a nearby white reference for our brain's "auto white balance." Thus, I find the paper white to maximum Lab B to be more significant than the absolute Lab B values for judging the warmth of prints that are aimed at being hung on the walls. With the relatively neutral printing papers like Epson Hot Press, the maximum Lab B of the print will be about the same warmth as a natural white mat board. I currently recommend Alpharag Artcare, 8 ply, Pearl White, #8647.8.
(Note that one of the variables in warmth for most papers is the drop size. Larger drops are cooler. With my old 7500, I could make a print on Premier Art Smooth Fine Art Bright White that had a Lab B value (absolute, not relative to paper base) that never went above Lab B = 0. That is, I could actually make a cold, 100% carbon print. However, the paper does have brighteners, and I do not recommend the 7500 as a printer. You need the modern Epson large format cart-to-printer coupling to be able to reliably remove the carts for agitation. All pigments settle; Eboni settles slightly faster than the OEM dilute pigments according to my centrifuge testing.)
I might add that with Eboni-6 and QTR, printing on uncoated Arches watercolor paper becomes very feasible. I consider "full sheets" (22 x 30 inches) of Arches Hot Press printed with Eboni-6 to be my top medium where one wants the absolute best possibility of a print that will actually last and look good for hundreds of years.
(Note that I have no financial connection with MIS or the sale of "Eboni" inks. I just design what I want on an open source basis, and MIS has chosen to commercialize some of these designs. To avoid undo profiteering from my work, I also publish the formula for a generic dilution base for Eboni MK, which MIS also decided to commercialize, but at a very inexpensive price.)
Hope this helps.
Paul
www.PaulRoark.com 
