Yesterday, my girlfriend remarked on how pleased she was with the effects of the hair moisturizer she has been using: "I started using it just a month ago, and look, it's healed all the damage." I complimented her, then said "...but hair is dead, so it couldn't have helped heal it." She replied, "Well it fills in the cracks". I accepted her answer; lots of hard-surface sealers work that way.
However, hair moisturizer seems odd.
- Unlike hair moisturizer, the effects of hard-surface sealers typically don't need dozens of reapplications to obtain.
- The exceptional sealers that do need several coats, typically do not need to cure before reapplication (although I suspect that some do). However, if a person were to apply coat after coat of hair moisturizer, they'd just get greasy hair.
I suspect that the porousness of hair necessitates the use of a "wetter" solvent than the one used in most hard-surface sealers, which protracts the curing time.
I also wonder whether the porousness of hair protracts the time it takes for the moisturizer to penetrate its fractures, and thus protracts the time the user ought to wait before reapplying: assuming the presence of the solvent along the path of penetration slows the penetration of the moisturizer then, the coats applied immediately after the first coat would penetrate the hair more slowly, and so they would cure closer to its surface, and would thus produce results that differed from the ones my girlfriend was so pleased with.
Are there substances that exhibit the properties that hair moisturizer seems to exhibit. At the molecular level, what explains why these substances exhibit those properties?