The 8 harness satin weave involves a warp yarn passing under 7 fill yarn, over one fill, then back under 7 and so on. The fill yarn does the same with the warp yarn. The most famous 8 harness satin weave we sell is the 7781 so we provided a microscope photo of it here.
To the right is a photo of the 8 harness satin weave style 3783 16 oz/sq yd fiberglass cloth that has a thread count of 54 x 48 ends/inch and uses the yarn ECG 37 1/0 in the warp and fill. All photos have different magnifications though one can infer the scale by a simple consideration of the thread count.
Here's a little closer look at the 16 oz/sq 8 harness satin weave style 3783. Photo taken with the side showing to obviate the orientation.