So I decided I needed some red ink for writing, as seen in many manuscripts. Of course it turns out that vermillion, that is, mercuric sulphide is a bit toxic, as is red lead, which is the other commonly used medieval option.
Which immediately makes me wonder what they used in the manuscripts I have been handling!
Fortunately the internet has lots of information, some of it from real people who know what they are talking about. It turned out that the simple safe one was a 16th century recipe using Brazilwood:
Of red colour, and first of Brasill.
You must take care when you seeth Brasill, that you do it when the element is clear, without clouds, rain, or wind, otherwise it will not be good you must make it thus:
Take quicklime poure rain water upon it, let it stand all night, in the morning poure the water softly from the lime or straine it through a cloath, & for a quart of water, take an ounce of Brasill, let it seeth till it be halfe consumed, then put into it one ounce of gum Arabike, two ounces of gum of a Cheritree, or else two ounces of cleane glue, straine it from the wood: you may likewise put into it some chalke beaten to pouder.
I thought I’d start simply enough, with 200ml of the lime solution and some brazilwood. Unfortunately my small scales aren’t good enough to weight out 5g of it, so I had to guess. Nevertheless, after 45 minutes of steeping and some boiling, I had reduced the volume by over half, which was this colour:
I filtered it out and heated it again, adding gum arabic. I don’t have any gum of a cherrytree, they aren’t very common round here, although the internet suggests it can indeed be used in ink or chewing gum. Here’s the bottle of it:
And here is the writing using it, red enough, but not the glorious solid red of medieval manuscripts:
The first writing I tried with it turned a bit blue, but it was probably contamination from the quill which had previously been used with black oak gall ink. Anyway, good enough to start with. Maybe I’ll try using red lead at some point, but I need a recipe for that. The linked source of the Brazilwood recipe has plenty of black ink recipes, but only one red one.