I've been using a fountain pen for over five years. If you've used a fountain pen before, you'll know that not all inks are made the same. I've been through inks marked as fountain pen safe that aren't, inks that aren't as colourful as you'd expect, or as solid, and the biggest problem for me is that I've always used ink that's not waterproof because.... waterproof ink will (usually) clog or destroy your pen. Noodler's ink is the exception to that.Of the ten or twenty ink brands I've tried, most recently Manuscript, Higgins, Winsor and Newton, and Dr. Ph. Martins, Noodler's is the best. All the inks I've bought are marked as non-waterproof, dye-based, and fountain-pen safe. They weren't. I've lost many pens because the inks were too rough on the insides of the pens. Noodler's is different. First of all, this is a 3oz. bottle for $15 including shipping. That's a really good price for this product. Considering all the "cheap" ink I've been buying, this ink is not only affordable, but far from cheap in quality. A 3oz size is nice too because I don't have to order more for a while.When changing colours, remember it takes a few cycles for the new colour to set in (unless you wash and completely dry the inside of your pen, which I don't do). After a week or so, I started writing in a deep violet colour, very close to the violet in the picture on this page. The ink is smooth and comes out cleanly, and dries in just the right amount of time. It enables me to keep the cap off my pen for longer and still be able to write, but also write without having to wait too long for the ink to dry on the last line I wrote. This ink is brilliant. It's also fairly waterproof. I wrote on a notecard and ran it under water a few minutes later, and very little of the ink came off. This is very relieving, having used ink that can be washed off the paper pretty easily in the past.All in all, this is a great ink to buy. I've used their green and black colours as well. Both provided similar experiences. Different colours do write differently, but they're all very good. I will definitely be buying this ink again.