I have a Waterman Kultur with F nib, and a Sheaffer No Nonsense with an italic F nib. The Waterman nib produces a much finer line. I am looking for an all purpose black ink, and possibly a red as will. I have not decided if they will both become eye droppers or possibly converters.
What ink can I use in both pens?

Technically, you can use any fountain pen ink in both pens. (i.e.- not calligraphy, india, or drawing ink)

Here's some suggestions to get you started:

In terms of black inks, Aurora, Waterman, Noodler's, and Pelikan are some popular brands.
Aurora is generally known as a very dark ink with great flow and excellent lubrication.
All Waterman inks are generally known as very well-behaved, and the black is no exception. It is less saturated than the other three blacks, but has very good flow and behavioral properties.
Noodler's is the only waterproof ink in this bunch, and it is also what they call "bullet-proof." It is often called the blackest black of them all, although I see it as looking very brown.
Pelikan Black is the driest flowing and least lubricating of the bunch. In a dry pen, this can sometimes result in skipping, but if you have a pen with a flow that is too wet, this can slow it down. I would say it is between Waterman and Aurora in terms of opacity.

As for reds, I don't have too much experience, but I like Visconti Bordeaux and Waterman Red.

Check out these inks and some others in the Ink Reviews section. If you're still not sure, or you want to try more than one, check out the ink sampler from Pear Tree Pens. (no affiliation)

I have used Noodler's regular (i.e. the 'bulletproof') Black in both pens and it works well. I really like this ink, because it's archival and waterproof and does not feather on or bleed through even the crappiest paper and because it always gives you a very saturated black line. In addition it's not as pricey as the other saturated black that's often recommended on FPN. However, it left some particles behind in the feed of my Kultur which I couldn't rinse out - not even after repeated soaking. They don't clog the pen or affect its function in any way, but you can still see them through the clear section (the small black dots in the photo).
Click to view attachment
(Another ink that stained the pen is Diamine Maroon, btw. At the moment it's filled with Schneider Turquoise, so those turquoise bits aren't stains but ink)
Hope this helps
Nellie

edited to add: great choice of pens, btw. - several of my much more expensive pens aren't half as good as those two !!

It would help if you gave some pointers for what you're looking for. For instance, some of the following are common variables with ink - which matters to you?


- Water resistance (or ease of washing)
- Secuirty ("bulletproof" inks)
- Depth of colour
- flow (how wet the line is when it is drawn depends on this)
- drying time
- feathering tendency (spreading out on the page; if you use good paper, this matters less)
- cost

Two standard blacks for me are Aurora Black, and Noodler's Bulletproof (un-removeable) black.

I rarely use black, so I have no recommendations for that color.

I like Waterman Red.

Private Reserve Navajo Red is a very good standard red. Well behaved, flows well.

Pelikan Brilliant Black is the black I'm happiest with after testing several: Sheaffer, Lamy, Parker.