Schwarzkopf Professional BC pH 4.5 Color Freeze Silver Shampoo 1LSchwarzkopf Professional BC pH 4. 5 Color Freeze Silver Shampoo 1L effectively cleanses hair and scalp while reducing colour fade, helping to maintain the hair's natural structure at optimal pH 4. 5. It preserves and revives cool tones, neutralizes warm undertones, and adds a cendre shimmer to white or highlighted hair and very light bases. What are the benefits and features of Schwarzkopf Professional BC pH 4. 5 Color Freeze Silver Shampoo 1L Helps