I mixed some waterman Florida Blue and Waterman Black along with some distilled water. The color is ok, but mixing ink is a pain.

Any suggestions for a nice blue black ink? It would be nice if it were permanent.

I 'm also curious to know if Diamine Registrar Ink is safe to use in fountain pens.

The Index of Ink Reviews has links to lots of reviews and responses.

Some BB's are a little blueish-greenish, some are grayish, some are greenish-grayish, some are blueish, and some are purplish-grayish. The drier-writing or narrower-writing the pen is, the less blue is visible in your writing.

The partially or fully permanent ones are some Noodler's colors (BB, Legal Lapis, Tahiti Pearl, Midnight Blue; what are the newer ones?) and some iron galls (bottled MB BB? bottled Lamy BB, Diamine Registrar's, Rohrer & Klingner Salix).

Edit: Diamine Blue-Black has been reported as somewhat water-resistant.

The iron gall inks marketed for fountain pens are OK if you never let them dry up in the pen (it helps to store a loaded pen on its side, not pointing nib-upward) and you flush the pen every few weeks. Also, iron gall inks have been reported as working better in wetter-writing pens.

Note: Noodler's Squeteague and R&K Verdigris are not permanent.

Diamine Blue-Black has a gorgeous color and even after soaking in hot water you can still read what you wrote, although i'd say the fading factor is 60-75%.

All the iron gall inks are waterproof. they lose most of the blue color but the black remains.

Noodler's does make some eternal inks. Ble-Black by noodler's could work for you but the colour is not nearly as beautiful as Diamine's.

I have a Lamy Blue/black bottle as well as a Diamine Registrar's ink on the way and i will be able to tell you more about them when they come in.


Mame

Sailor makes a very nice Blue Black ink. It isn't advertised as being waterproof, but it has better water resistance than do most inks other than bulletproof or iron gall inks. The color is nice, too.

I use the following Blue Black inks regularly:

Lamy
Diamine
Montblanc
Dupont Night Blue

All of these have passed my water tests with flying colors. Of the bunch, I have to say the Diamine is my favorite.

this mix is actually one of my favorites. i don't find it a "pain" at all... do you mean messy? in that case i use a syringe and works well.

once i did the mix (blue, black, distilled water), then i added a tinge of PR shorline gold... very nice! the color was in between PR sonic blue and Skrip BB!!!!

I use and love Noodler's blue-black. It's a dark blue-black, I think it looks like a black with a cool zing to it, so it's not boring. I think it is adverized as being "nearly bulletproof", or something to that effect. I suppose that it is Bulletproof Black mixed with blue, so the blue washes off but not the black.