This thread caught my attention, I'm glad there isn't a product that lasts 4-6 weeks,we would all be worse off financially, lol.
It is completely impossible for an externally applied solution to the skins surface to last longer than the loss and reproduction cycle of the skin.
Of course if it was possible and tans,in a fairy tale world,did in fact last 4/6 weeks this wouldn't actually have effected your revenue stream as you would have been charging appropriately more.
I guess if you sit back and think about it you would be doing less work for the same amount of revenue income:lol::lol::lol: