We examined silica coating methods on Fe3O4 (black), FeOOH (yellow) and Lithol Rubine BCA (RED) powders by means of atmospheric pressure glow plasma CVD with tetraethoxysilane. These pigments were deteriorated easily by heating or oxidation. However, cooling the discharge tube and depositing protective films on the pigments before plasma oxidation could prevent the deterioration. We developed three ways to make protective films, which suited each pigment's characteristics.