I was going through my Danish definitives the other day, and I checked the back of the 10 ore orange stamps from the wavy lines series. One of them looked like it might have been on laid paper, which isn't listed in the Facit catalogue, so I scanned it to get a good look.
To my great surprise, the paper has a honeycomb pattern, Here's a close up of the top right corner:

Extraordinary, I think!