In itself, the substance makes a decent impression, but the essential problem is that the substance with the use of studio flashes affects brown and not gray. The camera (EOS 6D) is farbkalibirert with a ColorChecker, the white balance (with 18% gray card) is measured and adjusted to 6850 K (corresponding to a color temperature of overcast sky or an electronic flash). Result: brown background. To set the background color neutral white balance of 4300 Kelvin is required. This corresponds to a color temperature of a fluorescent tube or a cold moonlight. If one uses a white balance of 4300 K, so the skin tones are rather an alien and go noticeably bluish.
Sorry, but the background goes back. How should I pack a 3 x 6 m background again acceptable to me, however, is a mystery, despite intensive efforts, this works is not really good.