The Seattle star. [volume] (Seattle, Wash.) 1899-1947, 1921-09-20

Northwest aitho some firms are
treating ties with . mixture Of Is
per cent crcosote oil and rs per
cent crude oil This combination
II not looked upon with favor b
engineers
Two methods Of preparation and
treatment are In common practice;
the steaming. vacuum. and pressure
proccsn. and tho boiling process.
which u another name for the open
tank method with tho addition OF
a pressure after tho water has been
boiled out OF tho wood The latest
and most modern plants are ualns
tho steaming. vacuum. and pressure
process refined and brought down
20 date. while many are stiil boiling
their timber. The boiling process is
more simple In its operation and re
quires a plant which can b con
structod Mt a somewhat lower initial
expenditure. 1t can be very sue
ces.sully used with some classes OF
timber, especially n first water
seasoned. but this process b open
10 some serious objections The pen
etrntion Of the Oh In fir plies when
treated In this way IL liable 10 be
very Irregular. varying In the same
pile sometimes from oneauartsr of
an inch on one side TO two and
one half inches on the other. Every
pile so treated has to DO bored at
one or more points to ascertain The
depth of The oil and In common
practice from to 10 per cent must
be returned for retrcatment on &C
count Of insufficient penetration.
This II caused by Q striking Pc
cuiiarity OF western FIR. which.
when exposed 10 the sun. and 10
some extent when air-seasoned. be
comes what ~ known among the
creosotinx fraternity ~ sun-bakcd.
tho exposed part being very bard
and almost iInpervious to the oil.
The sseaming. vacuum. and pres
sure process. although requiring q
somewhat more elaborate and en-.
pcnsivo plant. overcnmes In q great
measure both of these difficulties
and produces excellent results In q
period not exceeding - hours Re
cent tests made a, the forestry ex.
perimenfal station at the Uni
vcrsity OF Washington showed an
average depreciation Of but per
cent In steam-treatrd tsmbcrs. which
after two months recovered almost
their original strength.
During the first hours the steam
enters tho pores of tho cold wood
and condonscs. and later again
cvaporatcs when the wood rises to
the surrounding temperature. open
ing the pores so that when the
steam s blown off tho timber is
uniform as 10 moisture and well
heated throughout Undoubtedly the
blowing off OF the steam also has
tendency TO open tho pores. The
steaming need not be continued
longer than to feat the timber
through This In ties requires
from three to four hours and In
piiing from five to eight hours. ac-
cording TO the size of the timber
and the pressure Of the steam.
Having been steamed, tho drying
goes on uniformly under tho vac
uum. which Is the real seasoning
period and the most refined process
known To science. Timber treated
by this method Is found to contain
very uniform penetration OF oil.
as uniform. perhaps. rs could DO ex-
pccted In any wood whose grain
and density vary like that Of Doug.
las fir. II is very seldom. under tho
equalizing Influence Of this process.
that any timber Is found requiring
retreatment This fact together
with the high percentage OF remain
ing strength. Is certainly quite In
vorable to the latter process