The new De Atramentis Document inks (not to be confused with other De Atramentis inks) are a dream come true for those of us who sketch with fountain pens and want waterproof inks. Before they came along, color choices could be described pretty much like Henry Ford described color selection for the Model T Ford – “any color as long as it’s black.”
The current elephant in the room question is whether we’re going to have a ready supply of these inks over time. De Atramentis is a one-man operation and Goulet Pens, to my knowledge, is the only source for them in North America. Their last shipment came in and went out before some people had a chance to even see them show up. Brian has said their current order is very large. I hope so.
I was one of the lucky ones. I’ve had De Atramentis Document Black and Brown for a while now and was able to fill in the other colors during the few hours they were available at Goulet Pens.
The potential to create any color I want now exists, except for one thing. De Atramentis sells a solvent for their inks and proper dilution should be done with that solvent. These inks are pigmented inks and every ink have a particular chemistry to give them the flow and paper interaction properties of a particular brand of ink. The proper solvent should be used to provide the proper lubricant, stabilizer, and maybe anti-fungal agent in their proper proportions. The big deal here is the lubricant as this generates proper flow through the pen. Too much lubrication and you can get feathering, nib creap, and slow-to-dry inks. Too little and you can get a dry-writing ink, though it may actually dry more quickly.
So before I continue, there’s my caveat. If you fear doing anything that might be referred to as an “experiment”, read no further. This is an experiment. I’ve mixed up a grey ink using the brown and blue ink in this line. It creates a very dark grey, not unlike Noodler’s Lexington Gray but a bit darker. I wanted to lighten it up, but the solvent isn’t available to me, so I used water. Worse still, throwing caution to the wind, I used plain old tap water to thin the ink. Here’s what I mixed:
De Atramentis Document inks, not to be confused with other De Atramentis inks:
Brown: 3 parts
Black: 2 parts
water: 3 parts
That works out to 60% water, which is a lot but I found that when thinning other inks I had to add a considerable amount of water to lighten their color. This proved true for the De Atramentis Document inks as well, maybe even to a greater degree.

As you can see, I got a decent dark grey. I may want to play a bit with the blue/brown mix or maybe try a green/red mix but this is just about what I want on a tonal scale. Just enough to take the harsh black edge off my sketches.
The real point of the experiment, though, was to see how diluting with water would work. I’m surprised to say that even with this extreme dilution, the ink holds up nicely. There is no feathering, the line remains consistent and there are no flow problems with the Pilot Prera (fine nib) that I used to dispense it. I wanted the sketch to reflect the tonal differences between the black and gray lines so I used De Atramentis Black to do all the shadow lines on the right side of the bottle. After scanning I quickly slopped watercolor all over it and can report that the waterproof nature of the ink is retained. All of this is being done on cheap sketchbook paper. Just to ensure that it wasn’t the result of the paper, I did a bunch of scribbles on Stillman & Birn Alpha series paper and those were were waterproof as well.
By the way, there’s been some discussion of a Fog Gray color being added to the De Atramentis line. Those few who have had access to it have found that it’s really more of a grey blue than a true grey. Given that it’s easy to mix our own greys, though, it hardly matters.
For me, the experiment was a great success. To be honest I’m still a bit surprised because in my experience, dilution of pigment-based products (wood stains I’ve used) with water are very limited and things tend to fall apart once you get past 10-15%. Here I’ve more than doubled the volume of ink with water..and it still works. Go figure. I still wish I could get access to De Atramentis solvent but until that time…I’m going to go draw a few shades of grey.