... that the PPh is added before emulsion or when pigments are ground, so that it can easily couple ... effect, while having no effects on the stability of pigments, etc.Generally speaking, PPH is added 3.5~6 ... that the PPh is added before emulsion or when pigments are ground, so that it can easily couple ... effect, while having no effects on the stability of pigments, etc.Generally speaking, PPH is added 3.5~6 ...