Canvas print, cracking corner problems!

[mm371337]

Hi,

I've recently purchased an Epson 9800 printer along with

100% cotton canvas
Breathing Color varnish (matte, silk, gloss)
Lots of stretcher bars
Nail gun
Spray gun
etc.

I have all the kit but I'm having some issues. When I stretch the canvas the ink flakes slightly on the folded corners.

I'm using the 'hospital' fold technique which I suspect is causing the problem although this seems a standard technique.

I'm using at least 3 if not 4 coats of varnish before stretching (which Breathing Colour recommend).

Am I just being a little heavy handed or is there a way of avoiding cracks on corners?

Thanks