In a footnote in the booklet they referenced how they prepared their buckthorn berries since they bought them dried rather than fresh (from the same supplier where I bought mine). So, that solved question one I had about how to reconstitute the berries in a useful way. I figured soaking them in water would work, and had played with that a bit when the supplies first came in, but it was good to confirm it worked from a secondary source.
The recipe I'm using is in the Plictho and is the one I've been laughing about since I first got the book. It uses paternosters as a measurement of time (as in boil the mixture for the time it takes to say six paternosters). Now, I have no idea how long that is, but based on the length of text and normal speaking rhythms, I've guesstimated that it takes 1-2 minutes to say a paternoster. So, I boiled my mixture for 10 minutes.
I've done two samples, one with the leather untreated (other than using a deglazer to remove any surface finishes and dirt) and one pre-soaked in my alum water. I want to see how much of a difference it makes.
To make the dye I basically soaked some berries in tap water overnight to re-hydrate them. I then put them in a pot with a bit of alum, covered them with vinegar and boiled them for 10 minutes. I included the water I was soaking them in on the theory that there would have been juice in the berries if they were fresh. It may have weakened the vinegar a bit but I'm using strong vinegar (10% acid as opposed to normal white vinegar that is about 5%) so it should still be OK.
Once it had boiled I poured it into a jar and let it cool. It's a really dark, mucky colour. It almost looks black or dark brown in the jar, but when you paint it on the leather it's a bit like a dark olive colour. Interestingly, when you rinse the brushes, it comes off in the water as a yellowish colour (which makes sense since unripened buckthorn was used in period for yellows).
I applied two coats of colour on both sides of the leather and let it dry. Both pieces turned out a yellowish colour with a hint of green,
Applying a coat of olive oil darkened both pieces a bit. They definitely have a green tinge to them, but are in the yellow/brown tones.
Here are the pictures:
|This is the colour before I add the olive oil finish. Much yellower.|
|This is the colour after the oil layer. The piece on the right is the alum treated leather, the piece on the left is the untreated leather. Underneath is the yellow dye that I did in my first experiment as a comparison.|
The alum treated leather was much stiffer but otherwise I didn't notice much difference in colour or colourfastness. The green isn't quite what I was looking for, but it's pretty similar to what the Yale scriptorium achieved. I do have another recipe that includes verdigris, which might make a more blueish colour.