Is it obligatory for women to apply black henna to their hands and feet so as not to resemble men, even though this is considered adornment and may be visible to others?

A woman's use of henna is desirable (mustahabb). Scholars have differed regarding the obligation to cover the face and hands. Those who hold that covering the hands is obligatory would require a woman to cover her henna-decorated hands from non-mahram men (ajnabis). Those who hold that covering them is not obligatory consider henna to be part of the apparent adornment (zinah dhahirah) that does not need to be covered, except when there is fear of fitnah (temptation) or as a precautionary measure.