I cannot find pine bark locally but have purchased something called orchid
bark which, after a few phone calls to the company that bags it and ships it to
the local garden centres, I have been informed is all hemlock. If it was fatal
for Socrates, is hemlock OK for my cryptomeria?

Socrates' poison hemlock was an entirely different plant, a member of the
Apiaceae. Hemlock bark is from Tsuga canadensis, Canadian hemlock (or another
member of the same genus), a conifer. In this country we use Douglas fir bark,
a byproduct of the plywood industry. If it is safe for orchid roots, it is safe
for bonsai. However, how fine is it ground? I have found that the finest fir
bark available is only suitable for conifer mix. I gather that the finely
ground pine bark necessary for regular mix is only available in Florida.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)