ScottyEvil

No, fountain pens are designed with water based inks in mind. For alcohol based ink, or dye in this case, there are refillable felt tip pens.http://www.gouletpens.com/plat-cftr-250/p/Plat-CFTR-250 I'd try the ink that comes with it first, but if it runs, I'd just empty the cartridge and refill it with dye.

The ink slowly turns black over time, it is dependant on how strong the chemical reaction is. The pen is similar to what I have.

Can't say, I've never had to write on leather. Here's the results of my little experiment. You'll have to forgive the lighting and poor penmanship. Wetted down with water. Rubbed with a paper towel. No pigment, so no rub off, like vinegaroon. I didn't prep the leather. The pen point was a bit sharp, but I think this ink would work in a refillable felt tip or brush style pen, if you prefer that over steel nibs. And 45 minutes later. It will get slightly darker with time.

http://www.diamineinks.co.uk/listings.aspx?catid=20 Diamine Registrar's Ink, blue-black. I use a cheap flex fountain pen when I write with it. Just out of curiosity, I dug my bottle and pen out and did a test on some scrap. I'll upload the pictures shortly.

I'd try registrar's ink (iron gall ink) and a dip pen or cheap refillable fountain pen. No bleed as it is a chemical reaction just like vinegroon. Not sure if the leather surface would need prep similar to parchment, I've only used it on paper stationary.

Lowly pharma tech here. Make sure you get untreated as they also come with water activated dentifrice. For those that just wanted to try it out, ask your local community pharmacist if they have them. We carried them for hospice patients and would sell them individual for a few cents apiece. Also, don't mix them up with glycerin oral swabs, as some places use the term "oral swab" interchangeability. Brand names I used to order when I worked retail were DenTips and Toothette and the boxes were 100 count.

Looks like a wood burner or a modified soldering iron.

Dr. JPH: Would you mind creating a thread explaining what ingredients/process you use in making your own dyes or the basic recipe you use? I, for one, am curious as I've seen you mention making your own dyes in another thread. I hear making dyes and I think of crushing rocks for pigment and various alchemy type flasks of liquids. By the way, I really enjoyed reading your books. Truly impressive work. Scott