---In STMFC@..., <jack.f.mullen@...> wrote :
Not quite. Eggs were dipped in an aqueous solution of sodium silicate which dried leaving a coating which acted to seal the naturally porous shells. Eggs thus treated kept much longer.
The treated eggs would be opened in the usual way: breaking the shells.
And I would assume for boiled eggs, the boiling water just dissolved the sodium silicate, which still didn't penetrate the shell.