After becoming obsessed with Esterbrooks, I've felt a need to acquire an Esterbrook desk pen set. I really wanted to try out desk pens and see if I could really use it daily. While this never happened, I got a Platinum Carbon Desk Fountain Pen instead. This pen is particular in that it comes with a cartridge of carbon ink, which is waterproof.
The Platinum Carbon Desk Fountain Pen writes as smoothly as a fountain pen should and solidly. It has a 14K platinum nib and takes ink with cartridges. After the ink empties, I'm pretty sure you can just take a syringe and fill it up perhaps. What's interesting about the cartridge though is that it is stopped by a metal bead which plugs the whole of where the ink comes out. Just stick the cartridge in the pen, push with some force, and then the bead is dislodged and the ink is flowing. The pen feels very nice in my hand and looks very elegant with its elongated body. The cap feels a bit cheaper, but this doesn't mean that it not good quality. I guess it is because it comes with a stand to put the desk pen in, but I did not buy it and felt that the cap was sufficient for me.
I found that I really loved the carbon ink! It's waterproof and it dries reasonably fast compared to the majority of fountain ink pens. However, this carbon ink is lighter in pigment and is more so a dark grey than black. And also, because it is carbon ink, it is not suitable for all types of fountain pens and may clog up some of the finer more delicate ones (or so I have heard).
However, I found that I cannot ever posses a desk pen. In the beginning, I was able to use it daily and it was nice. Yet, as time went by and I became swamped with school things, I used it less and less.. and it made a big mess as the ink pooled to the bottom since I heard that a desk pen has to be stored pointed down.
In conclusion, I found that this pen is not for me. At all. I've realized that I really do need portability for me to actually use pens (daily), especially since I am not always at my desk. But, the carbon ink is really interesting and some people may be able to find good uses for it, particularly artsy folk who like to deal with watercolors and other watery things. I'm highly considering buying a bottle of Platinum carbon ink and loading it up a fountain pen, if I find the correct fountain pen to use it with.
The Platinum Carbon Desk Fountain Pen can be found for a mere 12$ at Jetpens.com! A fairly great price. (But it appears to be sold out currently). The accompanying stand can be found for 18$, and a bottle of carbon ink can be found for $22.50 - both at Jetpens.com.