Update on Blue Leather Dye

I've searched the city for powdered gum arabic with no success, so I ended up ordering it from a US pigment distributor along with my ripe buckthorn berries. Hopefully they won't take too long to get here. I could have probably gotten it from another more local company (I did find an online store near Toronto that carried it), but since I needed my buckthorn berries anyway I figured I may as well tack on the gum arabic at the same time.

In the meantime, I got impatient and did a bit of an experiment using the liquid stuff from Michael's.

The challenge with using the liquid is there's no indication of the concentration. Is it mixed at a 2:1 ratio? 3:1 ratio? More? So, when my recipe calls for an ounce of gum arabic, I really have no way of knowing how much of the liquid to use. I ended up just eye-balling it, which is always a good way to go with chemistry. :)

I boiled down the indigo dye as instructed, then added my gum arabic. I then let it settle overnight so the indigo sediment settled. To get a decent coating without too much natural colour showing through I needed to do at least three layers, but I suspect that would vary by batch.

The colour is very much a blue, but when I apply it to the leather it gets very dark. You can see the blue tinge but it really depends on the light. In some light it looks like a dark grey or even black.

It also didn't bind at all to the leather. I was able to use a damp paper towel and almost completely wipe the colour off the leather, after it had dried. I was worried this might be a problem with this recipe, since every other recipe using indigo I've seen requires a strong chemical like lye to break down the indigo. It could also be because I used the liquid gum arabic, maybe it wasn't strong enough. From what I've read, the gum arabic is supposed to act like a glue and help bind the colour to the surface, so its certainly possible. I'll have to try again when I get the gum arabic powder.

Even if the next batch binds better to the leather, I'm not entirely sure I like the colour. It's just not "blue" enough in my books. There are a number of other recipes in the book for blue, including one that calls it "light blue", so I may need to keep experimenting.

Me waiting for the watched pot of indigo to boil

This is the finished dye. You can see the blue on the glass is pretty nice.

In the light of the flash the dye looks black-ish but in normal light it is a dark blue.