What is more, there has been a discussion recently (can't find it now, but I think ReneZ was involved) about the specific properties of the iron gall ink and how some of it becomes much darker over time via some chemical reactions with the vellum. This process depends on the composition of the ink and it's not very easy to predict which parts will get much darker if the ink is not very evenly mixed. So, when the scribe initially inked the text, the text may have looked much less pronounced and the scribe may have felt the need to strengthen some of the outlines.
I think I saw a proper paper on this, but I can't find it either, so here's a link to a reddit thread: You are not allowed to view links. Register or Login to view.
There it's claimed that the ink on a page gets darker within the first 30-90 seconds, but then can get darker still within a day or so. However, I assume this is talking about modern inks made with modern technology. I vaguely remember reading in the past that authentic medieval recipes produce inks that take much longer to darken and are much less predicable in this.
I think I saw a proper paper on this, but I can't find it either, so here's a link to a reddit thread: You are not allowed to view links. Register or Login to view.
There it's claimed that the ink on a page gets darker within the first 30-90 seconds, but then can get darker still within a day or so. However, I assume this is talking about modern inks made with modern technology. I vaguely remember reading in the past that authentic medieval recipes produce inks that take much longer to darken and are much less predicable in this.