Quote: My freind I am sure that you never noticed a hen measuring the humidity but you stil do it!
It is a precaution from entering some nasty pathogens to your house.
You're right, but then I don't set dirty eggs, either. I'm sure there have been nastier things in this house in the last 43 years. My initial thought when reading your question, though, was that washing would remove the natural protection from the exterior of the shell, which may allow your sanitation agent to get inside. That brings to mind the practice of a horse breeder I once knew. He owned a valuable stallion that he stood at stud. Before he allowed the stud to breed a mare, he washed the mare with soap & water. I'm told that soap is a spermicide! All I know for sure is that my mare never carried a foal from that stallion. The question is for my freind that have suffered from Marek's that is decimating his flock, so he decided to re- start his flock and vaccinate his new flock, he decided, that although the convention is that MDV doesn't pass IN eggs and ON eggs shells he prefer to be on the safe side.
I don't know, Benny. I've never read anything about the possible adverse effects of a sanitation agent on embryonic development (which doesn't mean such studies don't exist). Lacking such information, I wouldn't do it myself, but everyone should do what they believe is right. It would be interesting to see what, if anything, happens if your friend tries it.
Maybe @ChickenCanoe could shed some light on it.