Good point. Perhaps a hot wash after the 24 hours would eliminate salt, or would the salt have been absorbed by the shell? I think its beginning to sound risky.
I really think you're overthinking this.
Just bake or microwave the eggs and feed them back (crushed up).
The membrane isn't a problem. There's probably some protein in it.
We are new to caring for chickens and have just started to prepare for their arrival. I have been reading several books about care and feeding of the chickens and read about utilizing the shells as a calcium supplement, not a replacement for other feeds. As a retired engineer I always want to research stuff and this was one of those times. Thanks for your input and I will take your advice.
Good for you to research thoroughly before jumping in.
You probably have a long time to wait before you need to worry about this.
Are you getting chicks, started pullets or mature hens?