WHAT IS THE PURPOSE OF PAINTING?

I recently acquired an old pine table that my father in law had made approx. 30 years ago. It was refinished by a family friend years ago, but has remained sticky. Papers, napkins, table cloths stick to the surface and leave a residue. What would cause this and how can

How can you tell if the exterior stain is oil or acrylic? Unable to get oil due to going green. Can an acrylic stain be applied over an oil stain? If not what must be done in order to use an acrylic over oil?