The benefits of glycerin for hair is moisture and retention. Why retention? Hydrated hair breaks way less than dry hair. Glycerin is a humectant with awesome moisturizing capabilities with its ability to draw moisture from the air and surrounding environment. Glycerin based products are very moisturizing when used properly. When used improperly, glycerin based products lead to extremely dry hair.
Optimal Conditions for Glycerin
Benefits of Glycerin for Hair
As previously mentioned, glycerin draws moisture from its surroundings. Ideally, it will pull moisture from the air, but when the air lacks moisture, it will pull moisture from the hair, leaving it feeling dry. Applying water to the hair before / after the glycerin based product just ensures the hair is properly moisturized so that if the air lacks moisture, glycerin can pull moisture from the water applied to the hair and not dry it out. I’m no scientist / chemist / stylist, so I can’t quite provide receipts and change why this works. All I know, I tried it and it works!