You can achieve desired stain of henna dye on hand using following two-
MEFIX TAPE-
Medical tape that's breathable, lightweight, and flexible. Allows for free movement all day and night without having to worry about stained clothes or sheets or flakes of Henna/Jagua in bed. Protects the paste all day and doesn't get in the way of your hustle. Applied when henna is 100% dry, and kept on as long as possible, commonly overnight. Just remove when ready and the paste will come off with it. Apply natural oils to the skin after.
TRADITIONAL METHOD LEMON JUICE & SUGAR
Traditional method of sealing the paste with a mixture of lemon juice and sugar. Melt 1:2 ratio of sugar to juice in microwave for 15 seconds and apply on dry design with cotton pad. Great for brides Mehndi night, and clients who want to show off the design while its staining the skin. It's not recommended to sleep with this or be moving excessively. Can be done at home after appt. Paste has to be removed with a blunt object and then finish off with natural oils.