Thanks Paul for your response. I usually just choose one lace for the perimeter which lately has been French as the SFS does not last long at all. For a while it was always SFS all the way around - up until about a year, year and a half ago. The SFS had been falling apart on me on the second attachment.

That being said, stretched, enlarged by moisture could be the case - here are photos of the base from a few mins ago -although it has a curve to it there seems to be little ripples although it just came off my head and has not been washed or anything.

The bottom line is it is as if you had to shape a piece of paper over the outside top of your template. There would need to be darts all the way around in order for every edge to be totally flush all the way around.

Maybe there is a stronger SFS out these days?