What ink should I use?

This is another question I don't think there is a definitive answer to...there are just too many variables! Is your pen a gusher? Are you using copy paper? What I can tell you is that you need to always make sure you are using inks labeled Fountain Pen Ink. There are other inks, such as calligraphy ink, that are actually damaging to fountain pens so stay away from those. I personally only use blue ink from Waterman in my vintage and antique pens( yes, I use these all the time). These pens have made it a long time and I want to keep them going. I was once told that Waterman blue is considered a "healing" ink because its so mild. For my new pens I am pretty flexible, I may put an ink in a new Pelikan and find it is far too wet so I change it to a dryer ink. Often with a pen that is new to me I will use ink from the pen manufacturer, assuming that they are formulated to work best together. Once I get to know the pen better its easier to choose an ink. There are so many beautiful shimmering and sheening inks and I love to use these as well ( side note, check out Shogun from J Herbin, great black/brown shimmering ink) but I start with those in a TWSBI with a 1.1 nib so I can see just how much clogging I may encounter in another pen. Circle back to that Shogun ink, I use that in a vintage Montblanc these days with a broad nib and have no problems at all with it...but I think its a process to get there safely. Last years Pelikan Edelstein Ink of the Year was Golden Lapis, an absolutely gorgeous blue with gold but it clogged the first three pens I put it in...including the Pelikan it was meant to be in! I finally figured out that there are just so many particles in the ink that now when I shake it up to mix it I let it settle just for a few seconds so some of the particles are already at the bottom of the bottle before filling, since I have been doing this I have had no problems with the ink clogging at all. Final thoughts...choose an ink color that makes you happy and ask questions if there are too many options to choose from, I am happy to give my opinion, just send me an email with your question and what pen and paper you are using, that helps to know!

Inks I can't go without?? Waterman Serenity Blue, Iroshizuku Yama Budo and Kon Peki, Akkermans Delfts Blauw and SBRE Brown, Montblanc Enzo Ferrari and 100 Year Coral ( I actually bought 3 extra bottles of this one so I won't runout for awhile!) and J Herbin Shogun and Emerald du Chivor.  Ink I wish I still had...Pelikan Edelstein Ruby.