Sanford, the company who makes Sharpie and many other fine products also makes Children's art products under two different brand names "Colorific" and "Foohy." While I really like their glitter markers and their double ended metallic/bold markers, it's their gel markers that are really fantastic. Why? Because they are opaque. You can draw a line in black and then moments later, go over it in yellow and the black does not show through. Sometimes you have to work to get the timing right when it's too humid for everything to dry quickly, but it's the closest thing I have ever found to drawing with acrylic paint.

I have been using these markers near exculsively for nearly a year for all of my work. While I haven't the slightest idea how colorfast they are, I've also decided to not care.

Sometimes, these markers are hard to find. So when you find them, buy all of them. You won't regret it. I swear.