This is probably a stupid question, but...
Do all inks spread equally - i.e. I'm not referring to flow through the nib but to the tendency for that spreading effect that one gets on certain types of paper (Is there a word for this?). Brought a pen filled with Waterman ink to work today and I'm having a hard time finding paper to write on without the spreading...

Spreading is typically known as "Feathering" and is a function of the pen, ink and paper. Different combinations of these factors will have different effects, and you can imagine how many different combinations there are. However, in my opinion, the pen itself is the single most contributing factor of the three. How much ink the pen lays down is the first factor. What the ink is, how thin it is, what solvents it is comprised of determines how well it feeds through the pen, and what it does once it is on the paper. Lastly is the paper.

I expect a pen to write on any paper. That isn't right, of course, but it is the starting point for me. (Fountain pens don't write on wax paper.) If I don't like the way a pen writes, the first thing I change is the paper. It's the easiest thing to change, right? Well, maybe. If it's my journal I change pens, if I'm determined to write with that pen, I change inks.

I'm going through this process right now, with a Duofold I just had overhauled. If it doesn't settle down, I'm relagating it back to the baggie brigade.

I really do hope this helps.

Noodler's Bulletproof Black ink is the best ink in terms of non-feathering that I have ever used. It doesn't even feather on cheap newspaper.

In a word, no.

No.

And the same ink may spread or feather (they are not the same thing) differently depending on pen, paper, and weather (humidity and temperature).

Use a different ink in that pen and you will get different results.

The combination of pen, paper, ink, and writer is not subject to exact science or to analysis beyond certain limits. One of the charms of writing with a fountain pen is that the resulting communication is unique and reflects the circumstances of its creation. Those who want consistent, exactly reproducible results would do better to stick with a computer and a black and white laser printer -- no personality whatsoever, always the same (probably why the federal government standardized on the combination).

Thanks for your responses. I'm awaiting some Noodlers inks (including black) and am looking forward to experimenting... And now that I know that the most appropriate word is feathering, I have taken a look at some of the previous threads which have been very interesting.

Lloyd and Bill (Unless I've missed something, its nice to see his posts again.) pretty much cover the question. Just a couple of quick ammendations: Noodler's Antietam and their Standard Green are also among the best behaved inks w/r to spreading and feathering. To avoid the problems of feathering and spreading I've taken to using very fine nibs on pens with excellent flow control.....viz. Sailor F nibs. Among other things I'm frequently writing very extensive margin notes on baaad ink jet paper. The Sailors manage this with nearly any ink, including the fast flowing PR Tanzanite.