Marble is a notoriously difficult surface for bonding. For starters, most marble surfaces have been polished with a very fine grit and as a result there are hardly any pores in the marble that would enable absorption and mechanical bonding of the new coating. Secondly over the years such surfaces may have been treated with various types of materials like varnishes, sealants, or waxes. Chemical bonding between such materials and epoxy based resins should not be easy.

In order to make sure that the new coating will bond properly I advise that all marble surfaces are thoroughly grinded with a diamond floor grinding machine. You want to remove all shininess and glossiness from the surface. You need to scrape the entire surface so it looks scratched. This is how you will enable mechanical bonding with the new surface.

Also the choice of primer is very important. Go with a low viscosity primer that will guarantee deep penetration of the surface. I always recommend selecting an epoxy primer with a polyamide hardener, such primers always do a better job at bonding with challenging surfaces.

Finally another factor that you should keep in mind is that marble is a cool surface. When working in the winter you should make sure that the surface temperature of the marble does not drop below the recommended application temperature of the product. Otherwise you may run into problems like very slow curing or poor flow of the coating.