All of our surfaces arrive to us already primed.  We do not prime any of our surfaces in our facility.
Claessens uses zinc white, bound with linseed oil as a primer.  The surface is air dried, sanded and then a coating layer (or 2) of titanium white is added.  The zinc is never used as the only pigment, but as a small part.
Artfix linens have an infinitesimal quantity of zinc in their priming, which does not affect its archival rating.