Hatching duck eggs and need help

[katiedecker1222]

We have 6 eggs incubating most pipped externally yesterday morning. Not really any progress today, they rocked a little but nothing since. Tonight I helped one that I wanted to check on. I picked a decent chunk of the shell off in the circle where is should be zipping its entire membrane is still intact. 2 questions when should I break into the membrane to give it air and what would its external membrane look like if it were dry?

 

[nuthatched]

Dried membranes will be brown. You can gently wipe water on the membrane to check for veins, if no veins, gently open a hole into the cell.

 

[nuthatched]

https://www.backyardchickens.com/articles/guide-to-assisted-hatching-for-all-poultry.72886/