The eggs looked very fresh when found, and the covering looked almost wet. I didn't disturb it enough to get a feel for its texture ("You can look but don't touch"). During incubation, when I misted the leaf fragment with water, droplets beaded on the surface and didn't soak in. Not sticky, I think; it didn't accumulate dust particles. I may be able to tell you more when I can retrieve it from the rearing container without letting too many nymphs escape.

Incidentally, the first linked photo of hatchlings shows material that might be exuviae sticking out of some of the eggshells. This is clearer in the older photo: . I wonder, do these creatures molt before/during hatching?

The leaf fragment is out of the container. The eggy patch is so small that all I can say after running a finger over it is, it's dry and smooth. Can you suggest any tests, like seeing how it responds to heat or trying different household chemicals to dissolve it?

Compare with this egg mass of Siphanta acuta, which you've observed on loquat before. The eggs are described here, and are said to be glued together with colleterial fluid... not a familiar term to me, but according to this it would be a sticky substance when wet; evidently not when dry. I'm satisfied with your description of its consistency--thanks for the follow-up.

I followed links from Google. Evidently, colleterial fluid is the stickum that attaches eggs to plants, and some insect species may secrete two kinds.