Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Doesn't write seamlessly

I've recently begun using fountain pens and started with one of the pilot disposable pens and was quite happy, with the exception of the ink running a bit. I got this pen as a Christmas gift but have not been entirely satisfied. I now have the opposite problem I had with the pilot pen. If I attempt to strike a line, even at slower speeds, I usually do not end up with a continuous line. I thought perhaps it was just the ink cartridge, so I got a converter and filled it with Noodler's polar black (after flushing the pen with an ammonia/water mixture), but I'm still having the same issue with not being able to strike a seamless line. Perhaps this is just common of the fine nibs, but it's been rather frustrating.