This is a question I received via messenger on Facebook. The question is simple and the answer can be too. But, to give a good answer takes up more space than a computer chat program is good for.
What is colored ink used for?
Colored inks in medieval and renaissance manuscripts were used for many things. Red inks were used successfully to draw the attention of the readers eye (as you are experiencing) and became known as rubrication though any color ink came to be known as rubrication. Colored inks were used for decorating manuscripts with thin lines as well as drawings. One very practical use is that colored inks were also used to rule the page making it easier to write the text. Colored inks were used for many things but these are the three most common uses in my experience.
There are three terms to explore when talking about rubrication and they all have the same root word, rubrico. Rubrico is latin meaning “To color red.” Rubricate is a verb that the Oxford American English Dictionary defines as, “Add elaborate, typically red, capital letters or other decorations to (a manuscript).” This definition is very limited in its scope but it gives us a good jumping off point. “Rubrication” is a noun and is the results of someone having rubricated a page. A “rubricator” was often a specialized scribe who did the rubrication.
Rubrication of capitals happened often at the beginning of text and sometimes in the text block itself. Often a title, or paragraph starter was rubricated. It was also used to begin a book or sections inside a book. Rarer we see that colored inks were used for entire blocks of text. Sometimes we see rubrication occurring in lists of important things so that the items in the list are easier to find. And any color of ink was useful for rubrication. Red is most common but blue, green, yellow and gold were used as well. Gold could be an ink but was most often gilded or painted on. As an aside there are recipes that exist for “gold ink” which are gold colored as they have no gold in them.
Here are some examples of rubrication from manuscripts I have handled.
Rubrication in the mini-book, Shelfmark Adomeit 9 Lilly Library
A line of rubrication. Shelfmark Medieval and Renaissance 29, Lilly LIbrary
Rubricated capitals. Shelfmark Ricketts 20, Lilly Library
A list of Saint’s Days in March. We presume that the saint’s days written with gold were the important days to the person who commissioned the book. Shelfmark Medieval and Renaissance 29, Lilly Library
Two rubrications right next to one another. Shelfmark Poole 11, Lilly Library.
Colored inks were also used in drawing lines as ornamentation. We see red, blue, green and purple inks in several of the examples below.
Shelfmark Ricketts 240, Lilly Library
To very complex full page decoration:
And even fun:
A variety of rubication and line ornamentation shown in this picture. Shelfmark Ricketts 141 Lilly Library
Did you see the bird done in red ink lines?
We also see line drawings done in colored ink. The Wall Street Journal has has an excellent slideshow.
And in practical terms colored inks were sometimes used in ruling out a page. Shelfmark Medieval and Renaissance 29 Lilly Library
And colored lines, almost exclusively red ones, were used in music staffs. I did not take good notes when I took this picture so I do not know the shelfmark of this antiphonal. It is also in the Lilly Library collection.
So what was colored ink used for in medieval and renaissance manuscripts? Just about anything you can think of. Pragmatically colored ink was used to rule lines so the scribe could write evenly on the page. Artistically colored inks were used to make line drawings and ornimentations. And to mix pragmatism and art colored inks were used to draw the eye of the reader to important things on the page in very pretty ways. Colored ink did a lot of work in these manuscripts.
For a look into making period inks one resource is, “The Book of Secrets Diverse Ways of Making Ink.“