Previous studies18 also were conducted on a UV filterb combined with crosslinkedHA gel in order to form a sunscreen product with increased surface retention and reduced absorption into the skin. Test samples, i.e., 4% sunscreen with cross-linked HA gel, and control samples, 4% sunscreen solution only, were applied to skin sites at a rate of 10 μL per site, and allowed to dry for 2 hr. The penetration of the sunscreen was measured by tape-stripping each skin site of application.