Go to staples and get the .5mm lead for mechanical pencils. They were my supply store before I started ordering direct from pentel. They also should have normal blue pencils as well.

You're looking for col-erase pencils, they're used in animation a lot.

The usual standard is actually an aquamarine col-erase pencil, I believe.

What you're looking for is col-erase non-photo blue pencils.

HOWEVER...

Don't.

Just don't.

Historically, these pencils were used because reproduction gear couldn't see the shiny blue lines they created, so the sketch lines would just disappear. Handy. However, modern scanners don't have this 'deficiency', and the non-photo blue shows up just fine.

But that's not the problem. The problem is that these pencils are very well known for destroying artists hands. They are hard waxy pencils that require considerable pressure to make any sort of mark on the paper, and this encourages the artist to push much too hard. Leading to both heavily imprinted paper and carpal tunnel syndrome.

Furthermore, despite the 'col-erase' name, the waxy marks these pencils make are, in fact, virtually impossible to erase. I think they call it col-erase because it's one of the few color pencils that can erase at all. But it's a bit of a overstatement to call them erasable. In the real world, you learn after a while to just give up on trying to erase the marks. They really can't be erased completely, only reduced. And even if they could, the indentations left in the paper from the induced pushing too hard would still be evident.

I know it seems like what 'real illustrators' and especially animators use, but it's not actually so. Non-photo blue pencils used to be all the rage and no professional was without them. But these days, the 'real illustrators' out there have learned to avoid them. Because everyone got their hands all fucked up by these things.

There's a reason why these pencils have become hard to find for sale.

The best pencils for erasable undersketch lines are normal HB or 2B lead pencils. Mechanical or standard art pencils both do the job well.

Thanks for the advice. I'll definitely keep it in mind. However, I still will be testing out these pencils. After watching Gami Cross work with one, I now see how it can allow for things the way a normal pencil can't. Specifically, by sketching in blue col-erase, regular pencil can be used as shading for the finished work, along with ink to solidify the lines. This will allow me to shade my pencil drawings without making a huge mess, which is why I haven't done so since my early days of drawing. If digitally scanned, blue pencil marks can easily be removed in Photoshop while retaining all of the ink and normal pencil marks. It's as easy as dropping out a color channel. But I'll heed your warnings and test it out on some unimportant paper before trying to go pro with it. Also, I rarely do any non-digital drawings, so I'm not worried about carpal tunnel syndrome. I'd sooner get that from my job as a programmer.

I know what kind of pencil you mean, but I don't know where to get them either. I always wanted to try it out too. <X3

Thanks for the info, everybody! I now know exactly what I need to. =}