We have a tanning air-brush that we bought from the US. It sprays special tanning liquid. It looks very natural. It contains something like paint, that is brown immediately, but wears off within a day, but it also contains the chemical that darkens the skin for about a week.
After a week she looks somewhat darker than normal, but you would probably want to spray every three days or so if you wanted to keep the tan. I am not sure that it is really that much better than a spray can from a drug store, but I suppose that it will end up cheaper if you use it enough.
It rubs off somewhat, you have to stand around naked for thirty minutes or so. If you shower after that, you will not be as dark, but less will rub off. I do not shower after, and my clothes have been ok. Though I would wear a dark shirt, not a light shirt, the first day. White bedsheets get some rubbed off that you can see, but it is not too much.
