Platinum Bottle Dye (60ml) Fountain Pen Ink

Both the blue black and the black are excellent inks. They seem to be iron gall inks even though they are listed as dye inks. They certainly have the superior behavior of iron gall inks on all paper. They seem fairly gentle iron galls, if they are iron galls. Absolutely no feathering or bleed. Pretty fine lines. Pretty waterproof. I haven't tested this but I'm told it's not completely light fast so if you plan to keep paper on which you have written in the sun, use Platinum Black instead. The Blue-Black is a fantastic blue-black. The black is not quite as black as some blacks but still plenty black. Highly recommended. Better performers than even Noodler's Black on cheap paper. But unlike Noodler's Black, these dry quickly on high quality paper and are really easy to clean. Very underrated inks. Excellent daily drivers. No real downsides.

I got the blue-black dye ink as a change of pace from Platinum's Classic Forest Black when I was working on crossword puzzles. And that it is.

This is a real-deal iron gall ink, although it's formulated to not be as aggressive to the pen and paper as that used in antiquity. It goes down a deep blue, dries almost immediately to a much brighter blue, then darkens as the iron compounds in the ink become insoluble and precipitate out of solution. The result is permanent markings on the paper. The dye may wash out, but the insoluble iron salts embedded in the paper will remain.