Since my powdered gum arabic came in before the holidays, I decided to make another attempt at the blue dye this week while I was off work.
I followed the same process as previous, boiling down the indigo and then adding the gum arabic before letting it cool and letting the pigment settle.
Unfortunately, much like my first attempt, it just won't stick to the leather. It just wipes right off the surface at even the slightest hint of moisture.
At this point I think my original suspicion may be correct, and this recipe may just not be workable. The water is clearly taking on the blue colour but I just can't get it to transfer that colour to the leather itself or bind to the leather at all.
I'm thinking it has something to do with the leather itself. Maybe the process used to tan the leather in period introduced something that would allow the dye to sink in or stick. Short of using one of the tanning recipes in the Plithco (which just isn't practical for me), I think I'll have to write it off for now. Which is a shame, because all of the other blue recipes use heavier chemicals, which I don't want to deal with until I can setup outside in the spring.
I've also started the process of getting a green and a red dye going. Not sure how well they'll work either. The instructions for the red are rather confusing so I'll probably have to try a couple of times before I figure it out. The green is also a bit of a concern because all of the recipes use fresh buckthorn berries and the ones I have are dried.
Guess there's more trial and error to come.