Sorry for the absent of a week, I was sick and had high fever >__<
Rohrer & Klingner, RK for short, is a German ink company which, as all other German companies, is very anal with details. The Document ink line, the 41s, postponed several times for the release (I placed the order once I know about the release and wait for almost a year to receive it =___= Oh well….)
Braun, brown in German, is not very brown from any prospect. In the photo it’s a little bit like brownish gray and dark gray in person. It is somehow similar to the Super5 Frankfurt (which is also manufactured by RK) – Frankfurt is gray, a #111111 gray, and Braun is probably #222222 with slightly yellow tone (oh well, it should be brown)
Very fast dry, about 12 seconds, and it will be even faster with finer nib or with a more controlled pen. Very saturated with limited shading. However, if you leave this ink dry out a little bit (within the bottle and the fill into your pen), the ink flow will be very very dry and there might be no ink for the first stroke.
According to RK, the document ink line passed ISO12757-2 (which I have no idea what this is about) and clammed they have resistant from erasing, water, ethanol, hydrochloric acid, ammonium hydroxide, bleach, and light. In my test, it does passed the water resistant test, however the color pigments were washed out by ethanol (there is 1 drop of EtOH at dry TIME and satuRATIon)
CP value: 85/100, the color might not be as useful as black (41700)