The boilers of early American locomotives were
often clad in what is known as 'Russia Iron'. In the days before
rolling mills were able to roll thin sheets, Russia Iron
provided a practical but probably expensive solution. It is the
blue - gray colour of this material that is so often imitated in
the boiler cladding of models and restored locomotives with
colours varying from sky blue to silver. It's a highly emotive
and sometimes controversial subject!
Russia iron was made by hammering thin sheets of wrought iron
into ever thinner laminations in the presence of oil so that the
oil became trapped in the material, eventually down to about
.025" thick. While the resulting colour was rust resistant due
to the embedded oil, it also took on a lustre that's difficult
to reproduce nowadays. I'm very fortunate to possess a small
sample cut from the (believed to be) original boiler lagging of
the locomotive 'Glenbrook', built in 1875 for the Lake Tahoe
Railway and restored to working order by the Nevada Railroad
Museum in Carson City in 2015. The sample was given to me by the
Museum director and still carries the planishing marks left y
hand hammering all those years ago.
It's not silver, or sky blue, it's a dark blue-gray, closest
resembling the modern RAL2008 paint colour. And that's the
colour the C.P. Huntington's boiler will be!

'Glenbrook' in 2015, a contemporary of the C.P. Huntington built
to bring timber down from Lake Tahoe to the Central Pacific main
line. Shown under restoration in 2012 and complete in 2015.