Trim off any splintery bits and leave it alone.

Thanks. Now I have to get busy and cut up the downed limb before it dries and gets as hard as, um, iron.

Mmmm - might be fun to carve, huh?

But, just to jump off from where Lazygarden's sent you - they found that pruning spray and all that stuff that people put on the wounds on trees could hold bacteria in, instead of letting light and air and the tree's natural defenses take over, so right on, no paint.