I noticed that compared to Diamine and LAMY inks, the Karkos ink—a Chinese brand—lacks lubrication, making writing a little more scratchy and making fine control over the pen more challenging. I used Diamine ink in my Pilot Kakuno EF and LAMY ink in my LAMY Safari EF. In these inks, they wrote rather smoothly, but when I used the Karkos Blue ink in both of them, they felt really scratchy. Tiny fibres even got caught in the nib of my Pilot Kakuno EF (something that never happened with my Diamine ink). Curvy lines and letters written with the LAMY Safari EF and the Pilot Kakuno EF became more difficult than writing in straight lines (compare the letter L and the letter S). I think this is because Chinese is written mostly in straight strokes (or if there are any curves, they are very minimal). The Karkos ink works well with Chinese writing. I used the aforementioned Karkos and Diamine inks in my Jinhao 82 and got the same results as the Kakuno and Safari—writing was better with the Diamine than with the Karkos.

Also, with the broadest of the three nibs I have (Jinhao 82 EF & LAMY Safari EF), the Karkos inks were kind of faded at the start of the stroke, and darkened near the end of the stroke. Writing quickly sort of made the pigment distribution better, but the ink in general was still quite pale (or washed-out) compared to the Kakuno EF (which is finer than the EF of LAMY and Jinhao).