sweet potato crisps

People online complain in comments that no matter what they do their sweet potato crisps do not crisp so they give up. 

These are crisp. First time. Although most are overly browned. 

I looked at two recipes and they both instruct to use coconut oil and rosemary, but I don't know why. 

I crushed sea salt in a mortar and thought, "Well now,  how much salt would I add to a single sweet potato?" Then used three times that much. That was a mistake. And I knew it at the time. 

I think I just now poisoned myself with salt. 

This sea salt has less sodium than table salt, but I still used way to much. When am I ever going to learn? 

Never!

That's when. 

I have a lot of baking trays each with its own Silpat, six I think, like a restaurant over here, so I baked all three trays at once and switched them around halfway. Why mess around? That's my motto.