So, how do ducks increase the humidity?

[Rosalinda]

I have 11 ducks in the bator in lockdown. I can't seem to get the humidity more than 75. I have a wet towel, sponges and container with water. I'm out of ideas on what else to do...

 

[SeaHen]

Isn't 75 as high as or higher than it needs to be? I just hatched out 7 ducklings in a Brinsea Eco 20 and never increased the humidity above 65%. My first attempt at hatching ducklings was in my home-made incubator with humidity pushed to 70 at lockdown, and several drowned in the shells. What type of incubator are you using?

ETA: Maybe more importantly, what type of hygrometer are you using, and has it been calibrated??