A process for preparing coated nanoscale quinacridone pigment particles,
includes: mixing a quinacridone pigment precursor or crude quinacridone
pigment with a first solution including an acid to form nanoscale
quinacridone pigment particles; adding the first solution and formed
nanoscale quinacridone pigment particles into a second solution including
deionized water to form a third solution and to precipitate the nanoscale
quinacridone pigment particles; and washing the precipitated nanoscale
quinacridone pigment particles in a fourth solution including a surface
additive compound, whereby the surface additive compound coats the
nanoscale quinacridone pigment particles; wherein the surface additive
compound is a rosin compound.