The timber for creosoting shall be long-leafed or southern pine. Sap
surfaces on two or more sides are preferred.
_Piles._--The piles shall be of long-leafed or southern pine, not less
than 14 in. at the butt. They shall be free from defects impairing their
strength, and shall be reasonably straight.
The piles shall be cleanly peeled, no inner skin being left on them. The
oil used shall be so-called creosote oil, from London, England, and
shall be of a heavy quality.
The treatment will vary according to the dimensions of the timbers and
length of time they have been cut. Timbers of large and small dimensions
shall not be treated in the same charge, neither shall timbers of
differing stages of air seasoning, or the close-grained, be treated in
the same charge with coarse or open-grained timbers.
The timbers shall be subjected first to live steam superheated to from
250 to 275° Fahr., and under a 30 to 40-lb. pressure. The live steam
shall be admitted into the cylinders through perforated steam pipes, and
the temperature shall be obtained by using superheated steam in closed
pipes in the cylinders.
The length of time this steaming shall last will depend on the size of
the timbers and the length of time they have been cut. In piles and
large timbers freshly cut, as long a time as 12 hours may be required.
After the steaming is accomplished, the live steam shall be shut off and
the superheated steam shall be maintained at a temperature of 160° or
more and a vacuum of from 20 to 25 in. shall be held for 4 hours or
longer, if the discharge from the pumps indicates the necessity.
_Oil Treatment._--The temperature being maintained at 160° Fahr., the
cylinders shall be promptly filled with creosote oil at a temperature as
high as practicable (about 100° Fahr.). The oil shall be maintained at a
pressure ranging from 100 to 120 lb., as experience and measurements
must determine the length of time the oil treatment shall continue, so
that the required amount of oil may be injected.
After the required amount of oil is injected, the superheated steam
shall be shut off, the oil let out, the cylinders promptly opened at
each end, and the timber immediately removed from the cylinder.
In the erection of timbers the sap side must be turned up, and framing
or cutting of timbers shall not be permitted, if avoidable. All cut
surfaces of timbers shall be saturated with hot asphaltum, thinned with
creosote oil. The heads of piles when cut shall be promptly coated with
the hot asphaltum and oil, even though the cut-off be temporary.