Is It the Sapwood, Or Is It Just Me?

When I bought a bunch of kempas 2×4s for my workbench, I didn’t know squat about selecting wood, and ended up getting a mix of heartwood and sapwood boards. No problem. I noticed that one board in particular was nastily face-cracked, which I read means that the board is entirely unusable. (Side note: Could the board have already had all the face cracks, or was it perhaps because I planed it before letting it dry enough first?)

Well I’m working on a box for my wife, and want to use some sapwood as a sort of inlay on the top. Since I only need strips that are about 1/8” by 1/2” and a few inches long, I figured I’d try to get it out of this face-cracked board. Now when I cut a piece off, I noticed a couple of things:

• The crosscut is glassy smooth. I mean seriously, it feels like glass. Is that common for sapwood, or is it my awesome ryoba pull saw skills? The rip cut, by the way, wasn’t glassy but cleaned up really smooth with my plane.
• This wood is rock-hard and seems heavier than the heartwood.
• The pores appear to be “dirty” – you can see what looks kind of like “bleeding” or staining that seems to come from the pores. Even if this is natural, it is not attractive as it looks accidental.

So my question is: Is this normal behavior of sapwood? Or is it because I’m using a ruined board? I figured I’d ask here first before sacrificing another sapwood board, because I’m trying to save most of them for my actual workbench. Here’s a pic of the piece I cut off (click to enlarge), and thanks for any words of wisdom you might have!

-- Eric at http://adventuresinwoodworking.com