The penetration of ink components into paper was studied by applying i
nk formulations containing C-14-tagged varnish to paper Surfaces of th
e treated papers were ground to provide a uniform gradient in thicknes
s from one side of the sheet to the other The relative mobility of pig
ment and varnish were measured on the ground sheets. Varnish penetrate
d to a greater depth than the pigment for the three inks studied. The
pigment content of the ink was an important factor in dictating varnis
h ingress