As already said by a few others - Sell the one you don't really want & buy a black one. Dying the kilt won't give you that deep black that you want - There'll be some parts of the kilt (say the thread) that will be of a different material construction that may resist the dye & give a different result because of this. The only way to dye the kilt proper would be to hand it over to a company that specialises in industrial dying. Just sell the kilt and buy the black one that you *really* want!