Monday, June 25, 2012

Scrutinizing the Scroll Part III: Investigating Ink

I had not originally intended to followup my previous two posts (Scrutinizing the Scroll:" Papyrus, Parchment and Vellum and Scrutinizing the Scroll Part II: Comprehending the Quill) with a third post about pigments and dyes. That being said, I also had no intention of following the original Scrutinizing the Scroll post with an additional post on writing utensils. However, based on speculation on other blogs, as well as the potential for application to game play, it was inevitable. I'm just sorry it took this long to get to it.

That may be blasphemous to certain clerics or to those wizardly sorts that think of magic as an art but, when it comes to color, it starts with the science of light. Without getting into a whole discussion of the basic difference between additive color (e.g., TVs, PDAs and computer monitors) and subtractive color (e.g., physically written and printed matter), know that this discussion will be limited to the realm of subtractive color as we are restricting ourselves to a consideration of the written scroll and its game world implications and applications.

In subtractive color, certain wavelengths are "removed" from (the total spectrum of visible) light. This is done through the use of pigments and dyes that filter out certain wavelengths to reflect the remaining wavelengths back from the substrate, and allowing those wavelengths back into the eye. So a pigment or dye that appears blue, actually filters out all of the other colors, allowing only the blue wavelengths to enter the eye. (NOTE: fluorescent, phosphorescent, and other forms of luminescent materials actually emit light.) Pigments and dyes are quite similar in the way they react with light (especially in terms of their color properties), but are vastly different in the way they react with the substrate to which they are applied. Simply put, the difference between pigments and dyes as color substances is this: pigments are insoluble and dyes are soluble.

For a pigment (as insoluble matter) to be applied to paper, it must be accompanied by a binding agent that will both: A) hold the pigment into a form that can be held/applied, and B) allow the pigment to be held to the writing substrate. Some binders are naturally darker than others (e.g., walnut oil compared to linseed oil), and each has particular way of reacting to temperature—and that's what it all comes down to. Dependent upon the binder being used (and, on occasion, the pigment), the key considerations of clarity, finish, smoothness of application, and so on usually come down to the temperature. How quickly does the oil/fat heat? And to what temperature should it be heated in order to remove the most impurities, most readily incorporate the pigment, best sustain or achieve the desired color, and produce the consistency desired for application? And then there's drying time.

Regardless of the method of application (brush, finger, stick, et al.), because the pigment is insoluble, it must "rest" on the surface of the substrate (paper, papyrus, et al.) Though the oils from the binder may bleed into the substrate and have affinity with it (see "Dyes" below), and some particles of the pigment may stain the substrate, as a whole the pigment does not.

Dyes, because they are soluble (unlike pigments), are normally applied in an aqueous solution which may or may not include a mordant (from the Latin "mordere", meaning "to bite) to give it fastness (usually included in dyes used to dye fabrics so the dye doesn't "wash out" from the fibers.) Also because they are soluble, dyes are able to form a bond with the surfaces to which they are applied (having affinity). Whereas the binder acts a "holding agent" for pigments, the aqueous solution acts as a "carrier", bringing it to the surface in a form that will allow the dye to form its bond.

Pigments and dyes come from both organic sources (vegetable and animal matter) or inorganic sources (minerals).
Example Plant Sources: roots, berries, bark, leaves, wood, fungi, lichen
Example Animal Sources: insects, cephalopods
Example Mineral (Inorganic) Sources: clay, iron oxide, lapus lazuli (an ultramarine semi-precious stone)

For the purpose of this discussion, we will use the term "ink" in a broader way than the restricted definition many have for ink (as something you use to write with) vs. paint (which is not something used to write with.) In this discussion, ink is simply a viscous substance (liquid or paste) that holds/carries pigments or dyes and is used to apply coloring/marking to a surface.

Regardless of formula, an ink commonly comes down to four components: 1) colorants (pigments and dyes), 2) vehicles (binders/suspenders), 3) additives (to control flow and thickness), and 4) carrier substances (to keep the pigment/dye even distributed in the fluid matrix). Additionally, the additives and/or carrier substances may perform the duty of inhibiting the growth of infectious agents (like mold).

Additionally, inks generally fall into four classes: 1) aqueous, 2) liquid, 3) paste, and 4) powder. While the viscosity of an ink will determine whether a quill can be used of if a brush or some other writing utensil (e.g., a stylus) is required, powdered "inks" are much more contemporary and are most commonly found in thermographic printing (you know.. those cheap "raised letter" business cards... yup... that's a powder that's "melted" onto the paper.) Powders, however, may be used as an addition to a written sheet to aid in drying.


Dyes can often be removed from plant and animal sources by boiling (or capturing/extracting in the case of insect or cephalopod secretions) and pigments are simply ground into a fine powder (putting that stereotypical mortar and pestle to good use). Colors can often be changed, enhanced, and/or synthesized through other means (e.g., interaction with other substances or through exposure to certain temperatures).

While pigments are usually much more color-fast (hold their color longer without fading), they can often be more expensive for a couple of reasons: 1) their source (e.g., semi-precious and precious stones and metals) and 2) the quantity of pigment required compared to dyes (which are much easer to "thin" with the use of a carrier.) The strength of a dye can also affect the strength of a scroll's desire effect. For example, a scroll written with a "watered-down" ink may produce a much weaker effect than a scroll written with a deep, rich, "uncut" source ink.

What of those pigments and dyes that absorb and re-emit light in the ultraviolet spectrum? Yes, they are invisible to the human eye, but in 1e many creatures are capable of seeing into that spectrum. That "blank" piece of vellum could easily be a True Seeing scroll written in an otherwise "invisible" ink that is easily seen by vision in the ultraviolet spectrum.

There is almost no limit to what pigment or dye source can be used to create an ink, or what you can do to it to achieve an effect; just understand the other (non-coloring) components required to create the ink, and that the process by which the ink is applied to the surface (per the Comprehending the Quill post) is dependent upon all the factors discussed above.

Now all that's left is to incorporate all of these posts into a game system for creating scrolls.

I guess I better get started on that.


  1. so where do iron-gall and lamp-black inks fall: pigment-based?
    (india ink, sumi ink, etc)

    Also, (semi-science related)
    "optical whiteners" (like in your laundry detergent) absorb incident light from 'invisible' wavelengths (i.e., ultra-violet), and reemit that energy in the visible light spectrum.

  2. Lamp-black does qualify as a pigment (e.g., Japanese/Chinese ink sticks, "India" ink). As for iron-gall ink, as I understand it, the conversion of the source material begins (acid extracts coloration from the oak galls) in a liquid form. The liquid is reduced by "drying" and the color changes (from clear to "black"). When it's mixed with the additional agents it's still in a liquid form so technically I believe iron-gall would be considered a dye.

    As for things like "optical whiteners" that "convert" energy, it depends on what the substance is and how it's used. For example: the optical brightener in laundry detergent is a dye; something like a pearlescent coating on a hot rod is a pigment; the pyranine used in highlighters is a dye; the fluorescence of blacklight paint comes from a UV-sensitive pigment, and so on...