What is henna?
Henna is a dye made from the plant lawsonia inermis. Leaves of the plant are dried and ground into a powder which is mixed with liquids to form a paste that dries on top of the skin. Once the paste is removed from on top of the skin, a stain is left behind where the paste had been.
How long does the paste stay on?
Once the paste is dry on top of your skin, you can wet it with a mixture of lemon juice and sugar to help it to stick to your skin better and to deepen the stain. The longer the paste is on your skin, the better your results will be. My minimum recommendation is that the paste remain on the skin for 6 hours for reasonable results and 12 or more for best results.
Does it hurt?
No! I always mix my own paste using only powdered henna leaves, lemon juice, cajeput essential oil, and sugar. This paste is applied on top of the skin from a cone, much like icing a cake. Henna should never be painful unless applied over broken skin, since there is lemon juice in the paste. There is a product falsely marketed as "black henna", which is actually a mixture made with para-phenylenediamine (a strong sensitizer used in hair dye) that can cause chemical burns.
How can I make my stain last longer?
Keep the paste on as long as possible, with as little picking at loose pieces as you can. Once you have to take the paste off, remove it with the back side of a butter knife using scraping motions. DO NOT WASH IT OFF. It is very important that the henna paste residue be allowed to continue staining before it is completely washed off. If you shower, try to cover the area with plastic to avoid soap and water for the first 24 hours after the application of the paste. In addition to initial care, the henna stain will fade as the skin is exfoliated off of you, so any drying chemicals (soap and chlorine) should be avoided or limited where possible to ensure the stain lasts.
How do I sleep with paste on?
It can work to keep your paste on overnight especially for areas of the body that resist staining. To do so, you will most likely want to cover the area to ensure that bits of henna that flake off don't stain your bedding, or other parts of your body (think what it might look like if you slept with your hand on your forehead). Before covering the area, spray or dab on a mixture of lemon juice and sugar (1:1 ratio heated or mixed vigorously so that the sugar dissolves into the lemon juice) Be sure the lemon/sugar seal is absolutely dry before wrapping. For hands and feet, stockings make great henna covers that allow airflow and so reduce sweating and "smooshing" of the paste. For other parts of the body, plastic wrap laid on top, NOT WRAPPED TIGHTLY, works well as it sticks to the sugar and doesn't shift too much.
My paste is coming off before the 6 hour minimum. Will I still get a good stain?
Dry paste can flake off, especially in areas of the body that are used or moved a lot like hands, wrists, feet and legs. This is normal and expected to some degree and shouldn't affect your stain outcome too much because of the residue that is still staining the skin there. To avoid excessive flaking, be sure to gently cover the area with a lemon and sugar mixture described in bold above, and do not pick at loose pieces, or accidentally rub/bump the area that has paste on. If you have a design on your hands you will want to avoid washing them and certainly, submerging them. Instead use hand sanitizer on areas that don't have henna.
Should I avoid any activities while I have henna?
While the paste is on it's best to avoid bumping or jostling, sweating, and water because you may remove the paste accidentally. Submerging the paste in water (swimming/bathing/washing) is absolutely going to remove the paste and shut down the staining process as it removes the paste residue as well.