Hi there. Thank you for insightful explanation! This is good to know how to use appropriately the inks, as they were designed for their specific pens.

Thank you for sharing your experience, Alan! Indeed, with a fine nib the Noodler's Black Eel dries faster than applied with a thick nib. I am also using Noodler's Black Eel with a Lamy Safari (F nib) and it dries faster. It needs a bit longer to wait to dry completely, which might be an inconvenience when sketching on the go. Also, the time it gets dry depends on paper type. I noticed that Noodler's dries faster and does not smudge on 100% cotton paper, especially on hot- pressed paper. I think it absorbs better in the fibres of cotton paper, rather than regular cellulose type paper and consequently does not linger on paper longer than needed.

Noodler Black/Black Eel seems to have a mordant in it that helps it bind to the cellulose in cotton. That is safer for fountain pens than the finely granulated pigments in many other "permanent" inks. I read somewhere that the Noodler's black inks needs to be mixed before filling the pen, so I regularly do that. Some Noodler inks (certain blues?) are said to damage the plastics used in certain pens, but not the Black/Black Eel. "Bulletproof" is explained on the Noodler web page--as memory serves me it means it cannot be removed by water or solvents, so is proof against forgers. I have also had good luck with Rohrer & Klinger iron gall inks--a 50-50 mixture of their Salix and Scabiosa inks (I call it "Saliosa") makes an excellent waterproof blue-black ink that is safe for vintage fountain pens because that was the standard type of ink used before about 1945. (Note: iron gall inks darken overnight.) But one must be careful to very thoroughly flush the pen before changing to or from iron gall ink--if it comes in contact with modern inks it produces a horrible precipitate. Many modern inks called "iron gall" inks are so weak they are not water-resistant. The R&K iron gall inks are the only ones I have found that tame Pelikan nibs, which are very wet. (It makes sense to me that an old German ink would work well with an old German nib.) The R&K "Saliosa" seems to be comparable to the traditional Montblanc "Midnight Blue" ink, which has not been available in the US for a long time.

The Noodler "Black Eel" contains a lubricant that makes it work better in piston-filling pens.

@@alanjameson8664 Thank you so much for your insightful explanation! There is lot to learn about fountain pens and inks. I will take into account such valuable information if I will do a future comparison between inks. Also, I have just realized that even though Rotring ink flows well in Rotring pens and does not clog them, it would not be a safe idea to fill a fountain pen with Rotring ink.

Thanks for sharing your experience. I find that Noodler’s black eel ink dries much longer than Rotring ink and it is not completely waterproof as it stains the paper with a light gray shade after applying clean water. Maybe this depends on the kind of paper. I tried it on cellulose and cotton papers with the same results. I am now questioning the authenticity of my Noodler’s ink as many people I have been watching on this topic on KZfaq claim it is completely waterproof.

I haven’t tried but Rotring ink might be more viscous and designed for use in technical pens, which might clog the Pentel Fude pen’s feed mechanism.