I used Seitz-Kreuznach Tomato Red in cartridge form in a Kaweco Sport with broad and fine nibs.
Tomato Red is a very pleasant color. It’s lighter than many red inks, and softer. It’s even possibly too soft for me in a dry nib. But with a wet nib it’s a cheerful red color that never overpowers.
Here is Tomato Red next to Sheaffer Skrip Red, a standard red ink. You can see that Tomato Red is softer and less saturated, and has a pink tint.
I think Seitz-Kreuznach Tomato Red is extremely similar to Monteverde Red, as discussed in more detail here.
Tomato Red behaved very well for me. It started up well and flowed consistently. I got a bit of feathering with the broad nib on my “everything feathers” paper, but perhaps a bit less than normal with that paper, so it would be a good ink to investigate for poor paper.
I found it delightfully easy to clean, which is a nice feature for a red ink. On the flip side, it’s not particularly water-resistant. After contact with water, no Tomato Red remains on Rhodia, though some remains on poor quality paper.
Paper towel chromatography does explain Tomato Red’s lighter tint, since dyes in hot pink and a peachy pink are part of its composition.
Living outside the EU, I order Seitz-Kreuznach products from Seitz Global, which sells Seitz-Kreuznach ink in 100 ml glass bottles for $9.90 and in 20 ml glass bottles for $3.25. Short international cartridges are $2.19 for eight or $3.62 for 14. George Seitz kindly added this cartridge to an order I placed, so I could sample the ink, before they started selling the smaller bottles.
Fountain Pen Follies 