CompuServe Messages

While trying to create a boolean object out of mostly flat surfaces, I notice that sometimes on the edges between two booleaned objects, a triangle will be shaded funny, as if it were no longer flat with surrounding triangles. I also notice that this happens less when I opt not to weld vertexes, but I still cannot always prevent it. I understand in a polygon environment csg is sometimes sketchy, but I was wondering if anyone knew if there was anything more I could do to avoid this problem, and maybe correct it after it happens. Thanks – Kai.