The present invention provides an indexed support substrate. In an alternative embodiment, a method for producing a photo-screen device for a real image projection system includes the steps of printing colors thereon in reverse order and positioning the photo-screen such that the non-printed side faces a viewer of the real image. There is included a mixing arrangement for mixing the liquid with gas upstream of the nozzle outlet and to impart to the liquidgas mixture a velocity in the same order of magnitude as the velocity of the surface treatment jet at said outlet. The concentrate may, optionally, contain a deflocculant andor an anti-syneresis additive. The floating module has an engaging portion to contact with the semiconductor package when the floating module is at the lowermost position.