Hair has “plaques” which are like petals on a flower. When the hair is hydrated and covered with sebum, the plaques lay flat and smooth. If the sebum is removed by harsh shampoos or not replaced by a conditioner after shampooing, these plaques open up like a Christmas tree. When that happens, the hair tends to matt, dulls in color, dehydrates, and no longer protects skin properly.
This is one of the reasons why conditioners should always be used after shampooing. You wouldn’t just shampoo and not condition you own hair, would you? Applying a good hydrating conditioner and using correct grooming techniques will help maintain a healthy beautiful hair shaft.