That happens sometimes. If you are careful in your bending, using metal bands to hold the splinters down, steaming or heating the wood adequately, making sure the wood is at a good thickness for bending and is not overly thick, etc, than they usually do not go that deep. At least for me. Although there are some exceptions. For example, I just steam bent 90 degree recurves on 2 different hackberry bows, both bows had splinters lift when bending on the recurves, but both were easily rasped and sanded down. The last recurve I made before that had the same thing happen. But I also recently steam bent some 30 degree or so recurves on a mulberry sappling that was mostly sapwood. The mulberry was thinner, I steamed it longer, and the bend was alot less severe. But both recurves broke on the belly, and the breaks went about half the thickness of the limb. Added to that, the recurves didn't stay. I mean they stayed bent after I took them out of the form the next day, but when floor tillering, they bent back with almost no force at all.
