I put the folds in the fabric because I wanted to test the filter with a variety of moires. They seem to happen so randomly. When shooting still life you can try different things like changing magnification, lighting, angle, F stop etc. But the issue which is worst is when shooting people when the moire can pop up at any time as the weave on the fabric of clothes varies so much. I was hoping it might be good enough just to leave the filter on in these situations.
The Caprock filters come in different strengths, which relate to the size of the circles on the filter. The 5.6 is the second strongest (ie second largest circles). I did have the idea that maybe the least powerful filter (smallest circles) may be better suited to these high MP backs (I say high MP because I think they were designed in the days of 6MP dig backs). I would like to try some of the others, but at around $US200 each (once shipped), the results of this test is not encouraging enough at this stage to keep spending.
I don't know why the moire varies. It just seems to be the way the light catches the weave of the fabric.
I did send the test results to Caprock and asked their opinion, but got no response apart from suggesting opening up wide to get some softening. That is not a very practical suggestion for general shooting.