QUOTE(Deirdre @ Feb 20 2008, 05:45 PM) [snapback]520901[/snapback]
Also, I wouldn't recommend bottled MB blue-black in non-MB pens. The MB pens are designed to handle the acidity, but most brands are not (it's an iron gall ink).
I think we should be careful we we say most other brands are not capable of "handling" iron gall inks, when it is really the construct of a pen that may be affected versus an actual brand of pen that is affected. This is a contentious subject, so we should clarify what what iron gall ink is and what type of pens can and cannot handle iron gall ink. So let's review from a prominent source, Richard Binder's website:
iron gall ink (also ferrogallic ink or gallotannate ink) A permanent ink whose primary ingredients are oak galls (a source of gallotannic acid, C76H52O46) and green copperas (hydrated ferrous sulfate, FeSO4·7H2O, also known as green vitriol). More technically known as iron gallotannate ink, it has a pale color in its liquid form; as it dries, it oxidizes (to ferric oxide, Fe2O3) and turns intensely black. The addition of indigo imparts a blue color that makes the ink easier to use; on drying, the ink assumes a blue-black color. Iron gall ink is acidic, and its corrosive effects can destroy fountain pens whose nibs or other working parts are made of metals that do not resist corrosion.
and:
Iron gall ink was invented more than 1500 years ago. It was used by innumerable nameless scribes to copy sacred manuscripts; by great secular writers and thinkers such as Voltaire, Shakespeare, and Leibniz; and by ordinary people. When fountain pens came into existence, iron gall ink made the leap to the new technology, and it is still in use today because it is perhaps the most permanent ink of all, even more tenacious than Noodler's "bulletproof" formula. But it has a couple of drawbacks. First, but of less serious consequence for most of us, is its reputation for destroying, over the course of centuries, the paper on which it is used. Of more concern to you, as a fountain pen user, is that it is rather acidic: it can corrode metal pen parts such as steel nibs and cartridge nipples, and plated trim rings — every part that comes in contact with it. Only gold alloys are safe from its ravages; if your pen features a gold nib and has no other metal parts that are continually exposed to the ink (such as a metal cartridge nipple), you can use iron gall inks such as Montblanc Blue-Black and Diamine Registrar's ink with impunity.
My point is not to impugn Deidre, but to make sure readers understand the term iron gall ink and it's use in fountain pens.
Regards, Eric