I have a very old house with very old iron drains. In the past I've had two
different plumbers in to clean out clogs, and each has recommended a
different, exactly opposite, remedy. One snaked the drain, saying it was
dangerous to blow out an old pipe; the other blew out the pipe with air,
saying it was dangerous to snake an old pipe.
I need to have another drain cleaned, and would like to know which way is
best and least likely to cause damage.