Does henna containing oxygen act as a barrier to water during wudu (ablution)?

For the ablution (wudu') to be valid, water must reach the skin. If there is a substantial barrier that prevents water from reaching the limbs of ablution, then the purification is invalid. However, a mere color that does not prevent water from reaching the skin does not affect the validity of the purification.

It is stated in An-Nawawi's "Al-Majmu'": "If there is wax, dough, henna, or similar substances on some of one's limbs, and it prevents water from reaching any part of the limb, then one's purification is invalid, whether the amount is large or small. But if only the trace of henna and its color remain on the hand or other parts, without its substance, or the trace of a fluid oil that allows water to touch and flow over the skin of the limb, but does not adhere, then one's purification is valid."

In Ar-Ruyani's "Bahr al-Madhhab": "If one performs ablution while there is henna on one's hand, and the substance of the henna remains and has not been removed, then the ablution is impermissible; rather, one must remove it. But if only the color remains, it does not cause harm."

Therefore, what matters is that the water reaches and penetrates the surface of the skin.