Last Saturday, at the Fountain Pen Network-Philippines Christmas pen meet, I won a bottle of Platinum Blue-Black ink.
This is a dye-based ink, as opposed to the pigment-based ink that Platinum also produces. Pigment-based inks have bigger particles, making it necessary for one to clean their pen often so it won’t clog. Dye-based inks usually clean easily with water.
This is also, according to Platinum, a ferro-tannic ink. This means it’s iron gall ink, whose main claim to fame is that it’s reasonably water-resistant. As the blue dye eventually fades away with time or exposure to the elements, the part that is ferro-tannic remains black and stays on the paper. Some people don’t really want to call it a blue-black, just a dark blue, but the color is sufficiently attractive and sober enough to be used in many official situations.
I wish this was a review of the ink, but the Platinum 3776 Century Chartres pictured above is full of Pelikan Blue-Black ink. I will direct you, however, to the very reliable review by the Peaceable Writer, JD. JD explains that if you don’t clean your pen well after using Platinum Blue-Black, it may mix with your newly-filled ink and refuse to write. Here’s a more recent review over at the Goulet Pen Blog, which mentions one has to use and clean the pen regularly – long, unmonitored exposure to iron gall inks can cause corrosion on steel-nibbed pens or fixtures.
My last iron gall ink was the old formula of Lamy Blue-Black, which I enjoyed using. It did flake off a bit of the gold plating on my Pelikan M200 steel nib. I plan to use the Platinum Blue-Black in the Platinum 3776 Century, which has no decorative trim rings on the section that can be corroded, and whose gold nib and feed are easily removed for cleaning.