In my humble opinion, this isn't just an evolution… but rather a REVOLUTION compared to traditional brushes.
Since AK launched its new line, I’ve bought about forty pens for my ships, airplanes, spacecraft, and vehicles.

My only reservation: most naval colors aren’t available yet, which poses a problem, for example, when painting a US Navy "splotch" camouflage pattern (Measure 12). Perhaps in the future, AK will expand its line to include naval colors.
And I expect more rival brands will enter this business, as the pens are less dangerous than jars for airmail.

On the plus side: in my model-making projects, these tools have almost entirely replaced good old paintbrushes:
- each pen is ready to use in a second;
- no more need to clean paintbrushes;
- no more need to mix paint in a jar beforehand;
- the coats are more even and thinner than those applied with a brush, and very similar to those achieved with an airbrush;
- the paint dries quickly: 5mn in Summer, 10 in Winter on the other side of the Pond. As it dries, surface tension gives it a very even and crisp finish. The result is a coat that resists masking tape and scratches

The available colors are primarily intended for aircraft and armored vehicles, but the range is expanding due to commercial success.

Naturally transparent colors (red, yellow, etc.) look best when applied over a white primer. However, I achieve excellent results by applying four coats with the white pen to surfaces several square centimeters in size (1/144-scale space launchers) directly onto the gray 3D resin.

The fine, flexible tip allows you to paint very small details such as the landing gear shock absorbers on 1:72 and 1:144 scale models—and even the white ailerons on U.S. Navy aircraft at 1:700 scale! (Well, in fact I use to paint the entire aircraft at 1:700 and 1:350)
Admittedly, it can be tricky to get into tight spaces, but a paintbrush presents the same problem.

Finally, this ink works very well with Parafilm masking: it doesn’t bleed through.

In conclusion, since last winter, my paintbrushes have been slowly gathering dust.

HTH

Bruno