Confusion with Storey's Guide to Raising Ducks. Need clarification

[4-H chicken mom]

I picked up a copy of Storey's Guide to Raising Ducks to refresh my memory on incubating. On page 157 at bottom third of the page, he says "the correct reading on these instruments during the incubation period usually ranges between 82 and 85 degrees on the wet-bulb thermometer, which is equal to a relative humidity of approximately 55 percent on the hygrometer." Then the very next sentence he states " When eggs have been washed prior to incubation, the correct humidity level is normally between 85 and 88 on the wet bulb or 65% on the hygrometer."
I'm confused on this. Why would washing the eggs make a difference in the humidity?

Now if you look at page 154 #1 He states their eggs are washed in antibacterial soap. Which means he would be incubating between 85 and 88 on the wet bulb or 65% on the hygrometer.

But, then on #7 He states from day 1 through day 25, the wet-bulb temperature is run at 83 to 84 degrees. Which means were back at 55%.

I can't find my notes on last years hatching of my BEI's, so I don't remember what humidiy % I used.

What readings are most of your incubators running at?
Thanks.

 

[duckluck]

I was running at about 60-65% before I checked my air cells and thought them too big on my current upstairs (read: hatcher bound very soon) GQF batch and so I backed it down to about 55%. Downstairs Humidaire is varying between 84-87 on the wet bulb...we'll see how those air cells look, I may wind up backing it down too. I have 27 eggs in that right now, staggered group, all call eggs.

A veteran call duck guy told me he runs his at 55% before hatcher time.

 

[1lpoock]

The washing takes the bloom off of the egg, making it more difficult to hold humidity in, therfore; you have to raise the humidity.

 

[4-H chicken mom]

Well now that makes sense. Why don't they tell us that. Thanks 1lpoock for clearing that part up.

 

[tia]

55 for the first 25 days and 65 last three days.

 

[1lpoock]

Your welcome... I've read that book and the book of geese many times, I still keep looking over it and finding bits of info I didn't see before!

 

[CityChicker]

The right humidity can vary so much depending on so many different factors, like your machine, your location, etc... I really go more by weight and air cell size, altering humidity as necessary. Generally though, we keep our humidity on the higher end, most often around 60% (to 65% or so sometimes) the first 25 days. For hatching, we will bump that up even to sometimes as much as 85%.