interchange front and back of gluNurbsSurface


I am lighting some Nurbs surfaces (created with gluNurbsSurface). The material properties
(diffuse, ambient, and specular reflecty, and shininess) are the same for both sides.
But the back side never shows a bright specular reflection when the surface is moved around (with the light fixed). When I interchange front and back side (using th non OpenGL code that produced the surface) the behavoir changes accordingly.
So this poses 2 questions:

  1. How can I get the same apperance of front and back side of the gluNurbsSurface (especially specular reflections)
  2. How can I interchange front and back side of a gluNurbsSurface within OpenGL (glFrontFace seems not to affect the surface)