I'm not a knife craftsman, but I do make furniture and other wood items (clocks, boxes, etc) and I use a lot of maple, so here's what I can add.
First, the two hard maple varieties are Black maple and Sugar maple. While all maples' woods look pretty much the same, these two are harder and have more dense fiber to them. They machine very well, but you'll want to use dried (seasoned) wood, because they will change quite a bit dimensionally as they stabilize. Once stabilized and finished, they tend to stay quite stable.
Best way to color hard maple is to use aniline dyes. Maple takes dye well, and is forgiving -- you can wipe on more or take it off quick to control the shade. If the color is too dark or intense, you can rub the work with a cloth dampened with the dye base (alcohol or water) and it will take some of the dye out. After that, you can finish it with oil or polyurethane and it looks beautiful. Hard maple doesn't do well with regular stains unless the stain is a penetrating one, and then you usually have to leave it on for quite a while to get any kind of color saturation.
All maples can produce birdseye, quilting, or spalting patterns, and these forms of wood deformation (crotch wood, stress, etc) make for gorgeous finished pieces. Hard maple crotchwood is almost like ironwood in hardness, but a bit easier to work. It will chip, though, in smaller works. It's very important to make sure the wood is stabilized before working with these patterns so they'll hang together when the work is complete.
As someone already mentioned, toolmarks can be tough to sand out of hard maple. It's worth the work, but it does take some time. To give you an idea of the differences in hard vs. soft maple, consider the way bowling alley floors used to be made. The area with the dots, where you do your windup to throw the ball and all the way down to the arrows on the floor, were always made with hard maple. That way the landing ball (whether dropped or properly thrown) wouldn't scar the floor. The floor between the arrows and the pins were made of either soft maple or other variety, because the wear they took was only from rolling balls; they didn't need to be as tough. Bowling alley flooring, when you can find it, is great wood, because it was always treated and aged before use and it's in 1" thick, long, extremely straight and stable boards, and it was old-growth -- extremely close layering of the rings. That stuff is like cutting metal. My workbench top is a 7'x3' slab, it even has the dots where you line up your feet! This stuff could take a 10-megaton direct hit and all you'd have to do is sand off the scorchmarks. Anyway, when they tear down an old bowling alley, there's always somebody selling the floor wood cheap. That's how I found mine.
Hope this helps -- good luck! If anybody has any questions about using dyes with it, let me know -- I've made every mistake there is, maybe I can help you avoid some of 'em.
Specialized
