Has anyone had the problem with Perle Noire turning grayish in colour? I have my Lamy Safari 1.1mm stubb inked up with J herbins Perle Noire. After the initial inking when the feed is swimming in ink, the colour put on the page is a very deep rich black with absolutely no shading whatsoever. After a few pages the colour seemingly turns grayish with some shading. It's no longer the deep black black black like I was expecting. It's not a flow problem I'm pretty sure because the nib glides across the page. The ink is just less saturated than what I was expecting. Has anyone experienced this with this or any other black ink???