First of all, let’s be clear on one thing: a properly working fountain pen should not leak. Apart from the case where the pen is malfunctioned, there are other situations where you can expect leaks from your pen. If you’re used to carrying your pen in your pocket (other than your jeans, I hope) make sure the nib is facing upwards. If you place the pen in your pocket upside down, chances are the pen will leak because the ink flows from the reservoir through the feed causing the cap to fill. Once you unscrew the cap, excess ink will inevitably leak out.