Minimizing shrinking and swelling of wood by replacing the water with nonvolatile materials


Material Information

Minimizing shrinking and swelling of wood by replacing the water with nonvolatile materials
Physical Description:
Mixed Material
Stamm, Alfred J ( Alfred Joaquim ), b. 1897
Hansen, Lawrence A
Forest Products Laboratory (U.S.)
University of Wisconsin
U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory ( Madison, Wis )
Publication Date:

Record Information

Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 29614986
oclc - 758353564
System ID:

Full Text

June 1935

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I.. ~.i

No. 1PIOC2

Madison, Wisconsin
In Cooperation with the University of Wisconsin

The antishrink treatment described in this report is
not a Scure-all-ills"' proce... It is limit-d in application
to "L, ...ion stock; it is expensive .nd has not beon suf-
ficiently tested for reconmcidations regarding its use. I
Gives wntishrink protection cxcoiUl .: that obtained by direct
L.'. fL'nation over relatively :hor1t relative h-.11idity c.'.c
cycles, but whether the additional. protection warrants the
additional exporse is also as yet uniauirn. Further experi-
m ntation is now bcing carried on with the hope of finding; a
cheiape.r, r.ore Gnerally aplicabl. 'Acthod. Tl-oe extremely
hiLi adsorptivwe pox. r of wood for water ac-Los t:..e solution
of this nrobl.:i a difficult one.





A. T. STA2I:,
L. A. IL, 3Senior Scientific Aid

Forest Products Laboratory,-1 Forest Service
U. S. Department of Ariculture


Jhen either green or dry wood. is iiprc nated with "uat r-insoluble ii,
or molten wax or resin, the Li, cntin''; o al ierly ters the I
cally visible ca)illry structure. WVater in the fine swollen structure of the
cell wall can, however, be replaced by a liquid which is co].pletely .Liscibl
with water. This liquid if also a soiv.nt for waxes and resins can be r-p,.Lco,
by the latter at temperatures above the tieltinp point. This pro.ce ur' has beer
used for getting water-insoluble waxes, oils, and resirns into the int"ina.
structure of the cell wall, usinm cellosolve as the iterned ,t sclv nt. Only
a partial shrinkage of the wood frcaa the -reon condition occurs ad the subse-
quent dimension chances with chanc;os in e-uilibrix., relative hui.iidity are
materially reduc d. The process can thus se:ve as a co.iuined seasoning ar-
antishrink imprecnation tratr.ent for refractory species. DLta obtained by
the ordinary ipreronation i.;ethod, and data obtained by i1. preCntini ary vXo d
with the wax:es and resins dissolved in wood-sw1l1i solvents are iven fo.

Introduct ion

Tr'Iatr.ients for nint.inizinjC moisture content chages ... ...."
shrinkinrg and swelling of wood thliat have been e-ither proposed or successfully
applied d fall into two classes, (1) moisture-exclusion treat.... ntsn al.d (2)
moisture-retention treatiiients. The former class :.ay be further subdivided
into coatings and intrafiber trcat.ents. Coatini^ treatments can be still
further subdivided into external surface coati" -S nd total s'rfacel coatinf'.

IPresented before the Colloid Division, .-i.ric.n Oe-iical society, ,e. Yorz,
April 22, 1955, and published in Journal of Industrial and nhincerini
Ch.3iistry, 27(4):401-406, A )ril 1935.
9intaind at dison, is., in cooratio ith the University of iscoin.
*^.4laintained at Madison, Jis., in cooperation with the University of 'Jiscons2inf.



External surface coatings have received the most intensive study. Coat-
inrs that show a moisture-excluding effectiveness as high as 98 percent as co::-
pared to untreated controls when alternately exposed to relative humidities of
95 to 100 percent for 2 weeks, 60 percent relative humidity for 2 wvee:s, and
'either exposure for 6 weeks for periods of over a year have been developed at
the Forest Products Laboratory (1, 2, 3). These consist of coatings of alulinu-
leaf between coats of other materials such as paints and varnishes. Coatinfj
of varnish, enamel, or paint containing aluminum powder give a moisture-excludirn
effectiveness of 90 percent and better. Bituminous paints, Lranular pigment
paints, and spar varnish as well as synthetic resin varnishes all show a good
moisture-excluding effectiveness (50 to 90 percent) when a number of coats are
applied. Although this means of excluding moisture in many is very
effective, it has the distinct disadvantage of being dependent upon the coating
remaining perfectly intact. It is thus unsuitable for use where the wood is
subject to considerable :echinical wear and tends to lose its effectiveness
under severe weathering conditions. Subsequent cutting and nailing of the wood
immediately subjects it to moisture sorption.

It would seem preferable to give the wood a treatment that would coat
or fill all of the capillary structure as well as to coat the external surface.
Unfortunately, aluminum powder and other granular pig-cnts which form the basis
for the best surface-protecting are too coarse to penetrate the fiber
cavities bocau.e the con.unicating openings between the fiber cavities ra.-ie
only from about 0.02 to 0.4 ricrons in diameter (4). Impiflnation tests have
been made using various oils, waxes, and resins (3). I preonation of wood with
linseed oil, paraffin dissolved in gasoline, molten beeswax, spar var:nishi nO a
cellulose varnish under alternate vacuum and pressure treatment gave uois&ture-
excluding efficiencies over a period of 17 days exposure to 95 to 100 percent
relative humidities of 0, 40, 47, 55, and 63 percent, respectively (3). 'Jhen
the wood was merely surface coated with the varnishes by applying several brush
coatings, better moisture exclusion was obtained than by in-pretnatirng with the
varnishes. Evidently internal surface coatings are less thoroughly for:ied than
the surface coatings. One perfectly intact thick film sees to be superior to
innumerable less complete thin films. The foregoing *moisture-excluding efficien-
cies of impregnated wood are also liable to be considerably less over longer
exposure periods. 1:acLean.. iziersed paraffin-impregnated blocks of wood in
water and followed their dimension changsa and increase in weight with ti.e over
a period of more than a year. In all cases the treated specimens swelled as
much as the controls but it took 3 to 4 times as long to attain equilibrium,-

Sime work has also been done on minimizing dimension changes of wood by
retaining rather than excluding the moisture. Treatments with sugar solutions
(2) and with concentrated salt solutions are of this type. One of the authors
has shown (5) that wood imjr'.n?.ted with strong salt solutions does not start
to shrink until the prevailing relative humidity is equal to the relative vapor
pressure in equilibrium with the salt solution. For example, if a block of
wood is impregnated with a solution of zin-^siuc chloride of a concentration
that will attain saturation before the wood is dried to the fiber-saturation
point, shrinkage will not occur until the equilibrium relative vapor pressure

-lacLean, J. D. Unpublished For-ot Products Laboratory report 8-4 M22W (1J.3).


of the system falls below 33 percent In many localities this iuy 'n.svr vc e j
so one might say th.,t this ( ent af ords mlutoe an tisrirn rT ion r c 0 .
This is, however not the case :is at hig hud l il ab.lotb ...... oil
Thi is, .. ..~ ,i sir ,ie -.ntc -r r
much water t-hat i .'ill tend tc drip fro. the surface and cd.rr sait wit i.
This may continue until virtually all of the 3 salt las b in Io1t T' T bl '
then loses its aitisL.rink properties wh 'n again dried. This d.ffi'IALLy .'!
be avoided by oriGinally dryili, the block to a moisture cotint ,il, b olec.A
t at at which ashri g co .0c.... an .. '..yin a2 is a oing t- voal1 be
pervious to waYter but not to salt and which would not lousen fr'v:: ti., su .....'
under the osmotic action whichh 'ould result. It is !;tobl,
such a coautig sl'aterial exis-ts. Trea,,tinr, thV ico vw d 1.it3 ay le.s y o
salt, sucK as sodi.i chride., ujould 7.atcrially reduce tlio dri:)in*.L tendesncy
at high relative iip.idities. A sodiLr. ochlorid(- trotoud s, ci ..o ,ul J, -,
start to shrinkiI .t 75 OercnIlt reLativI '.i dity, o that bc 'ot ish rik v -
tuction would ilo be reduceXd.

Whn -' ood is treated 'it> witer-solub.e nat riils si, ef salt: :ji
sucaur, the solut' diffuses into the sater in the fine capillar s.r.t.r. o
the wood within I'.'hich swsolling takes plco thus civiln an intrafiber tr'a.. 0,,.
A salt solution xi ll, in fact, attain concentration esithin the ads)rbed
water_,o virtually thoK as in the bull: water (5). ...' a. -the water i: evapo'tDd3
the i.t 'will deposit in tV.- coll ] all, cutting doi total shrink 4- to tri,
oven-dry condition by an r'ioLunt eqiua to th, volume of salt doeosited (5). If a
water-insoluble -,aterial could be deposited within the cell ',alls in i:.iilr
manner, it would very likely 1,,ave an ape ciable effect upon th s..b qu ..t
shri'skin, mand swellin, nd, should have none of the inherent d-'-2av t'"e;; intro-
duced by using i ater- solub e, ateria Is L. IrIpr.rognation of oritie ri'(. en or (ry
vood v'ith water-ins oluble materials hovover, results mere ly in thK wonetration
of the microscosic'slly visible caiillary structure. 7Jat ar-i'solubl a iai.s
which do not sweoll wood te e can ,ntr t cell als oo only by
diffusion into a vood-s;',ollin solvent which is adsorbed by the wood, or by
the method of re)lace:m.t in which wter is_- replaced by a series of 'Luids in
succession each I' wh ich is completely> :scible with thC 'ollo'i. liuid (6)

E xmper moaental

Ti.s p aper is rn mntroductor, sve:y cf the intra"i"e- ti at
wood with uatcr-insulublot aterial;; usi" th.. replacemn 1 ... i ffa...' "
method s. The effective ,,ss of r'et'rding th sr inin a ; i f _oo
obtain .' ,ith thos< treating processes is co; paarod with thK eifec ivo :.; of
total s-rface coatings obtained by dirct L-proa Ation.

The trcatm entis w.ere 'odAo on sm.all wood blocks of 7:L. it: i' .'...
xpproxiratstly 9 by 2 by f c. The lon-, ar esioo n 6s i te tU2 1nAti al
direction. Ashuirt di.nsion in the fiber cirection ce, C; .. :;de to
etlinat th.- factor of penetration. Th- results thu's s'. i ;a1 L" 1 ,e.ts
i ."er ce:D)!ete l'pregnavtion condition,-;. .TI :a t" 2, ]e..;t in ei
present st u.t of &v 1;I t .. .. sC~n
pre-sent st. o: ., arOe nol ap licable f r treating al)rc specir-s,
of re'fr_.ctory spocios T: T f e tive.s o' reducing, te 3 rir'-i..- a.d s wil d
ing of many forms of di.ension stock, :- ve'ry wel]1 be conuid rably less th"a

RI : ,i-


the values given in this paper, even under the most drastic treatments. 2n1-
-r'in block floorin-g and other similar forns of sraall i. ,-n-.ion stock, however,
fall well within the realm of treating by these methods.

Air-dry wood with a moisture content of 7.5 percent ws chosen as thu
starting i:iterial. The swelling of the blocks given in the following. t34 i.;
are front this condition.

Replic;nt Process

In order to riake the replacement fr-c',ss as simple as possible, it is
desirable to use a single internediate replacing liquid which is c,:ltely
*iscible with water and with the water-insoluble materiall that is to be
deposited within the cell wall. The liquid should also boil above the boilin--,
point of water to facilitate its replace ient of water. Cellosolvo (ethylene
glycol monoethyl ether) was found to be an ideal solvent for this purpose
(b.p. 1300 to 156 C.) and was hence u,.-ed for all the replacements given in
this paper. It is cc.'.pletely miscible with afterr at all t ei.,peratures arnd with
various waxes, oils, and resins at only reasonably elevated t.. ,oratures. Table
1 gives the temperature above w'.ic. the various L.mprcnatinF sr.atcrials used
flom a solution with c2llosolve in any proportions. The effect of .idi s"all
amounts of water to solutions of beeswax in cellosolve was determined. Co.iplete
mriscibility was obtained when 5 percent of water was added to a solution of 5
percent beeswax in cellosolve. Separation into two layers resulted when 5 p'r-
cent of water was added. The- lowv water tolerance of the ,-ystn thus e-akesL it
imperative that the roplaceiont of water by cellosolve be quite co..pll-.o.

The blocks wore weighed to 0.01 ra... and tlio di:.ens ions doter Linod with
a .micromreter caliper with an accuracy of frio_ 0.002 to 0.006 cmi. Th,1 blocks
wore then soaked in water in a vacuu.i desiccator, the ai r being removcad 1.r',
the blocks by alt-rnate evacuation and rleasir4n, of the va.'.... This procedure
brought the Loij;t:..'c content considerably above the norimial ren coiidition.
This was done to XHk the replac..-.,nt conditions uniformr:i a nd as svero as would
ever be encountered in practice. T".; bloc':s wore the,!n eOic,1 ,, iC-.;LLrecU, eJid
soaked in cellosolve, the volu... of coellosolve u.,_- being about twice that of
the water contained in the blocks. After soaking for about a weeok the water
was distilled off under a vac.',L,' of about 60 cm.. of .lurcury (teaT]pOrature 400
to 45 C.).

The distillation was carried out in a number of steps, each a dey apart,
in order to insure complete outward diffusion of water and inwarmd diffusion of
cullosolve. About 20 to 30 percent of the total volumie was distilled off each
time and an equal volu-,o of fresh cellosolve edl,;d. The water content of each
of the succeedinr distillates for a batch distilled ei*,ht tiics was 53, 41, 19,
5, 1.6, 1.3, 1.0, and 0.4 percent as determined from the refractive index. Af-
ter the last distillation two of tho blocks were dry distilled on a steam bath
and the water content of the total distillate determined. On the basis of the
dry weight of the, wood it was approximately 0.2 percent. T.he" possibility of a
s'all Eamount of volatile ,xtractive :-torial in the wood distillinm over with
the cellosolve and .-.ter made this determination of tho r,"sidual wator b;-
rofractive index a little uncertain. For this rc-s.-.n a similar replace.oent

R -062


of the mattere r in cotton lintors alpha cellulos by ccllolov' ;as .
r-sidual water in this case was found to be less than 0.1 perce-t. iirtu .1 iy
all the froe and adsorbed water in wood can tus boe relaced by c1l1so --
This replacem-nt : ado without any shr,"i-0 occurring; in lact, t'.r 'is
a slight increase in dimensions resulting from soa.king of tho ,at .'-swol.a
blocks in ccllosolve. Althoui a slijit shrinkage aco.a)'nied t. f V
water, the di:-iunsions in thc dry cellosolve in general remained slit -
greater than the original wuater-soaked dL'mnsions (fig. i).

Subsequent replacements of tihe water with collosolve in blocks rt
moisture content just belov.w the fiber-saturation point of the wood (av rag
moisture content 25.1 percent) wore carried out b heating th blocks in .llo-
solve to 70 C. under a vacuum which just caused continuous distillation. The
total distillate obtained in 24 hours containied 20 percent .?ter, .id the
blocks still retained 5 percent of oater as dctc;r.iinod from thj dry distillation
of the blocks. The total distillate obtained in 43 hours unucr the sa:'. condi-
tions contained 6.8 percent water and the blocks but 0.25 percent ..'t,;r. It
is thus possible to replace the vjatr ',ith cellosolvu much faster "... te
replacements used in the regular measuremcnts if the initial caoistur t c _oUt t
of tho wood is at thu fiber-saturation point ur less. Continuous distill-tion
and the use of higher temperatures and less vacuum are also atdvantaeous.

Preliminary measurements made by R. C. RounIs at the Forest Prouctl s
Laboratory indicated that the replacement of a wter-soluble inteu diale re-
placing, agent by a nonpolar liquid cannot be :'.ade so cfficientl, fro the
standpoint of constancy of di.ensions as the original replac .,ent (table 2).
These replacements with the exception cl' the acetone-toluone re1placemient,
were made in a continuous distillation-extraction appa.ratus in hich the liocks
were kept continuously,.od in the distillate. This was neces ary as the
replacing liquids boil at lovjer temperatures tkan the liquids repl, c,. Th
last value given for the purcentaie retention of th- s:wellin in wvter was
determined under the most drastic replaceent conditions and is pe;apu ne
rc*r sentative value tian th,, others. In all cases t)- values ore IpteticI ly
constant for the replacement iwitu the diff rent nunol,.r liquid.., ..... vais
replacing agents. Althou_ all the water hld belo tuic fiber-saturationa point
(29 percent for th white pine) can be replaced by at er-soluble in.ter..di te
replacing agents without accompanyinC shriankage, about 19 percent e th- re-
placing agent corres2ondin to a moisture content of tuo t o!" 0f .5 percent
cannot be repl.ceod by am nonpolar liquid, alt.olug it can 1e Ue'ovw i the
,resenco of the nonpolar liquid w.iIh acco.a .yig shrink Lge It is int.r, sting
that this moisture content cu=rresonds close ly w:ith the moisture colt-nt at
the inflection pointt in the Ioisture co:tt-relativ vaor r. Cu2ve
hich, in tur.i, is believed to correspond to the initial surfacc-bcunu mono-
molecular lay, r of water (7). This surface-bound .wattr caui ap nrently b re-
placed by swelling a, .!Lts which have _ain affinity for the wood but net by non-
polar liquids which themselves show no affinity for wood aiiC cause no swelling.

after r-_placinrg the water with celiosolv the r'ular'' t-'st bloc:, ere
placed in oils, molten waxes, and .:olt a ru,;ins and .,d Lat te ... r; .tu'es
sli '-tly in excess of those given in table 1 for more tl"an a a:e to a iow the
outward diffusion of cellosolve and the invward diffusion of t:e treatin
material to bake nlacre. The cellosolve was tin' distilled ,.)ff under r reduced


press-ure at these temperatures in the p:resence of an -:-.cess of wax. A number
of distillations several days apart were imade to insure complete removal of
the cellosolve. In all of these distillations only cellosolve distilled over
so that each distillation was continued until no more visible condensate could
be collected. Thl blocks were then weighed and measured and placed in a 90
percent relative humidity room at 80 F. All of the determinations were made
in duplicate. One block .s kept in the 90 percent relative humidity room for
0 weeks and the other for 2 weeks. The latter were next placed in a 30 per-
cenIt relative hLumidity room at 80 F. for 2 w..eeks and then returned to the 90
percent relative humidity room. These block s were put through five c(_. plete
cycles after which they were placed in the 90 percent relative humidity room
for 6 to 8 weeks. The blocks that were hold for 20 weeks in thie 90 percent
roomi were then placed in the 50 percent relative humidity room for 6 to 6
weeks. The diriensions of each block were determined every 2 weeks for the
first ,0 wr-.ks ,.nd then again at the co,.letion of the humidity tests. T-e
retardations ofi the shrinking and swelliri occurring between 10 and 90 percent
relative h-.umidity referred to the control (volume change of control minus the
volilue change of the treated block divided by the volumee-change of the con-
trDol) are given in table 5 for the average of four 4-week relative hm-:idity
change cycles. The first 4-week: cycle gave s E.ewrmt erratic results for so2e
of Lhe specimens, presumably b-,cau.;e Cll thl- ceilosolve had not Leeni previouly
compLetely removed. wor t hi- reason tuh .veraes for cycles numbers 2 through
5 are Civen. i:miilar values for the ) -rc:ntaj. retardation of th'; sorl-i:.
and swellinE are Jiven for a long, cycle (20 wekes at 00 percent r.oitive
I uidity and 6 to 8 weeks at 30 percent relative humiidity)

The volumetric swelling of blocks of wihte pi.e from the air-dry co. '1-
tion to different stages of the process tf replacing l the witer with stearin
are shkwn diagreu:aatically in figure 1 togth-,r 7ith t:he swelling occurring,
at each step in the subsequent 2-3week e::iosures to 90 and 3C percent rlativ:
hui iditj. Corresponding, data for the control and for direct ,preg6ation with
stearin trc Livcn for comp-iison.

Data are givenri in table. 4 for th- retardation. of the shrink:ing and
swelling of wood under various drastic replacement conditions. The values
for no distillations are for cellosolve replaced blocks socakod in molten oils
and :waxes for a w.eek. Subsequent values are for blocks fro,, il-hich cellosolvo
was reoiovd by differe-it mribers of distillations 2 days apart.

Dirp ct p. i *. t ._-t ion

,ir-dry blocks ,ere also im'pregnated directly with te oilj, molten
w"xues, &aid moltei resins by imersin the.i in the liquid at about 83 C. and
aiternl.Itely pulling a vacuum and reaisi.; until air bubbles; no loigr appeared.
Th .4ere put through the s,-ie rel,.tive hkmtidity cyclos :s tihe blocks, im-
pro xated by r .nlac met. Te rutardations Jf _ri: I ard .i> reeaiqi
J=)],Lie~ threat ,,,nts,, .1re i~vr .1 t2- 1 3 zi tli! 5'-7( b Iti /f or 15 -j .. Ilt
*U ,,a t., -I it ;


Diffusion Process

Oven-dry blocks ,'r ; aso i pren ated :itr solution ol i I i, (is,
and resins, dissolved in ,ood-swce1 i.-: solvents, cellosolv .tyl '"
and acetone. Thy i-,mr -n tion .'as carried on i4n a, rilu .na..r t-. ; 2;'
ii.iprLranliOdn u maintaineded. Tie blocks a.,ro heated in th; .'._ .eat tin& so0li>. os f :r 4 t, I
days at t 'ar sli :..l blo-: th boiin point to .r. ot diff.sion
the solute into the ce1l ualls. The volumetric s(A"lin. f ':ood in t: ..':
solvents rel,.tivo to its s-.jollin, in vjator arc c -1.osolvc 35 percent, .. K:7
alcohAol 94 p. rcont, and acetone 65 percent. Th, trotd bloc: ec di
in a vacuizt ov:;n at 'b C. afta'r jhich thy -aCJre subjected to siai! r r'.-
tive hu, idity c L .:,3 cycles to tho,- -... for tstinG the ant ish"rini: ef-
ciencios of thui other treat d blocks. Te results are givn in tabl"e 5 fr
the retardation of the shrin:in', and swellin{: obtained dur'in( one 4--.,'en cyc'.

Discussion and Conclusions

It is -vident from table 2 and co!'"2 of table 5 that the .....
efficiencies of replaceriont of :-;ater v.tilth a uiter-insoluble :-.ter. 1rr:.
the standpoint of retention of the vwatcr-swollen dimensions of .o, is ab '
80 percent. The value riven for rosin is higher than 80 percent but this i1
undoubtedly due to the fact that the residual cellosolve as not c:.plet ly
removed in the :.iolten rosin. bccessive, of the rosin :iad' it pr cti-
cally i-,.ossible to re>-ove the last traces of cellosolve. The relative l hih
hyprosccpicity of Plycoryl tonoricinoleate indicating, its polar nature countss
for the more co...plete re,)Lacenei,,t in this case.,

Replacerent of .', a' ell sol.. alone shso cn o i ; in th sub-
sequent cquilibriuw. swelli:, and shrinking (table 5). Thc relaclja.. t .f .
cellosolve avit> .'axes, oil, ir rsrsi" does, hodtever, decre!aase O', sI-t
dLi, .:.;ion changes. The best results -vere obtained .ith beosn'x, stee.ri:,
rosin, si linseed oil and rosin, u.nd oil and'a.. Rsi:.
is not satisfactory, honorer, as it c,-usod rather s verv chec'i :;, of th; ._1'jd.

The efficiencis of tLibo trat_-ints on o ea l a s"cS i s .' i ral,
p.ararll.led those on a volun:e o3h nnCL basi. Tre'at:.ents -:it> hr..sooic >a-
terials such as the diclycol olcat ad an1d'. ryl rionoricinoleate,, cave
negative efficiencies on a iht ha basis. The antis.rinLc f-ct of such
terials is evidently si]i.a in .ichanisn to the antishri k effect obtained
aith inorganic salts, ., :'ate'r buinm retained rathr than bein;. excludA .

T'h effi.cincies obtained by direct i-nioroination with the :.oitn ..a.f
oils, and r esinLs are less than t'l se obtained by th: reolace --'nt '.i.toc aith
the exception of pxaffin in which case the, efficiencics are prIctically the
sate. In the replace..nt ... :;ith -araffin very little par'affin ant .d t'- cell
.jall of the wood as indicatcd by the 1e,' retention of aater sellia. (s.
column 2, table; 5). This .ill accounml, for the fact that the r lacuoe:t :eth4.d
had no advantage over thu direct i-.-regnation nethod -.'irn trat irn. jti ) 'a:' J'i..


In all cases the efficiencies for retarding the shrinkin, and swelling
of th; treated wood d(Ccrcaso with an increase in tho tino of (xposuro to each
of th. r ltive htmnidities. (Column 4 versus 5 and columnn 7 versus 0, table
5.) This indicates that the retardation of shrinking and swellir,, is I- .ru ly
a matter of docroasing the rate of sorption of water rather than a shift in
the true equilibrium.

Increasing the efficiency of the cullosolve replacement with lXuZ,s
oils, and resins M.aterially increases the retardation of the dimension changes
as is shorvn in table 4. These data, together jithL the diffusion data given
in table 5, indicate that it is not enough to get some of the trcatirIL material
into the coll wall, but that the whole structure should be filled to -bt-iin
high efficiencies. Fairly good efficiencies are obtained, however, by the
simple diffusion process with bees.,:-': and combinations of beeswax with other
atetrials when 50 percent solutions are used. The useu of a morc volatile sol-
vent than cellosolve is desirable in this process but, unfortunately, most of
the highly volatile swelling, ;olvents, are poor solvwit, for the natural waxe,:s,
oils, and resins.

If more highly moisture-resisting materials could b, found th. t would
dissolve in wood-swelling solvents, the amount that would hv to be pt into
the wood to give good efficiencies might be materially reduced. Such ;i amaterial
is now: beine, sought.

Thu ruplac.: -nt process not only materially decreajia the di-.elnsion
changes but it also causes a r.-tontion of :':r.. nearly the greoi diirmnsions
of wood than any other treatment (fig, 1). The replacement process is thus of
as great if not gre.atur value in cutting doun the degrade of wood due to the
shrinl.i:C> occurring on initial seasoning as it is in maintaining unifomi
d i.nsions.

The replacement ijrocoss as here deccr'ibod is unquestionably too ex"'.i:sive
for general use. It should, however, be of value in seasonin(g a.d rct.iil n:_
the dimensions of small u!xpensive articles nade from refractory woods. In the
case of voods, th.; seasoningr degrade of which is small, the dry wood can be
impregnated with a nonaqucous wood-swvellini solv-.nt and th,. rplacmi:nt carried
on from this stage, thus avoiding the expense of replacing the water with cello-
solve. The simple process depending me,:rely upon the diffusion of the solute
from a wood-swelling solvent into the cell wall is not as yet in a state for
r .corrn--i.ndation. Bec-use of its sim licity, further studios along this line are
being made. Impregnations with synthetic resins under various conditions arc
also being studied and will form the materiall for another p-per.

Literature Cited

1 Brovwne, F. L. Ind. -ng. Chem. 25;835 (19'355).
2. Dunlap, UT. ,. Ind. "ng. Chom. 18:1250 (1926).
53. Hunt, G. E. Cire. 1W8, U, S, Dopt, of Ajri. (1930).
4. St'JIu" A. 'T. J. Phy",. Ch,,-i. 56:312 (1932).
5. J. -,.r Ch-. oc. 56:1195 (1954).
6. Ind. ]nL;. Chem. 27:401 (1955).
7. c nd Leughborough, W. '07 J. PhT.' Ghei., 30:121 (19315),


Taible 1.--Tcrm:pcratures abovc: u'io the i::Dre(ncatJTY *a~t-ri'- ,I
are soluble in cellosolve in all r ''.r rtLo i

ApO'roxi.-xiat( Tn lperraturo of
I ,it er i : rIeltinL : cr. 'lcte
p point i:miscibility

0 ,*'J.' 0 *
o o V'

p ..;n acet i.......... : .'. .

P f in. ............ : 57

Beit .' x.. ......... : 6
t : l . *

iao ax ........ . : 90.
R< si 0. .. ....... .... : 8b.:
LiTuns ,d oil . ......... : .............
Tunf oil. .. ... .. ..... : ........,...:



.Solule a roonto .poratro,1in*I1iuui point of oilt.
..i scibilit; not n:r; ri. n I.

Table 2.--Rectrnftion of the ex ternal voIUA trick Lielsion-ch::;o s-o-lli of "ite
phin in v t..t r r...ult1:o fr :.. t.. ... -placer.,,ie t of th .. t P AtU nI-

: !ntcrndite
Replacing : replacing

: Retention of suil!-
: int in warter r ,;ulFti
: froc t reac:::nt

: Per cent

Toluene ............. Alcoho l-acet F ... F 8.9
: 84.0
: : 8".3 .0
8 4 C,
*. 1. '.
Petrol um1 ether.. .... ,eflo ,lve........ : 8o.
(boirii, point : : 84.L
200 40 0 : : -31.7
,, *.ene.............: Diacet n alcohol...: 85.0
D(: (;: oov 81.

: : !6 .5

: : -SO.7

.All but this wvlu(i o c tahen fro: ti orelijinar, v1tudy b-
R.C.lomnds at tie Forest Productr L boratory. In 0c cooI, )f tihe
last v;lun, tho *',t}ors crrriod ..n t. o extra.ctio or 5. j(
resriduul collosoivw IOs h t .n 0.5 rcent.c as dote .i I ..- ...
the refrractive inde:- and fro ji ic tc t


Table 3.--Retsrlatlor. -f tr- sirinkinz si. swell ir_ f "_hr.ittejrir 'i1je t. tr-.9ir,--t Tithr wayeq arid 311 fr
relqtlve ri m1 t L etweer. 30__ rer tF A

T7re:i:, material


Replacement method Direct impregnation method
: Weight of : : Weight of :
intention of : wax or oil: le-ardation of : wax or oil; Retardation of
:water swelling: in wood : shri:rin' end swelling in .-r.' shrinking and swelling
after : per unit : ----------------------- ---- per unit : ---.-. ...
replacement : weight of : Avera-e of Long : w.irt :; : Avr e of Long
Swood : '+ slor cycles: cycle : wood : 4 short cycles: cycle
(2) : (3) : (4) : (5) : (6) : (7) : ( )
Percent : Percent : Percent : : Perze.rt : Percent

Untreated control.........:..,............ .....,.:
Ce.losolve only........... 102.0 : 2.11
Paraffin ..................: 2 .5 : 1.42
Spermacetli................: 38. : 1.58
Feeswax.................... ..41.60
Stearin................... 9: 1.79
Stearic acid..............: 66.1 : 1.69
Fal wax...................: 63.9 : 3.14 l
Rosin ..................... :86.1 : 2.31
Linseed oil...............: 59.3 2.0o4
Linseed oil (heated)...... 50.7 : 1.52
Tur. oil..................: 68.0 : 2.06
TuLit oil (heated)........: 53.5 1.42
75% Linseed oil, 25% rosin: 75.4 2.12
Linseed oil and beeswax...: 69.2 : 1.98
Linseed oil and stearic :
acid.................... 6 '...6 : 1.93
..:iycol cleates ............. 7.? : 2.10
Olycoeryl Monoricinoleate.., q'.5 : 2.28

- 1.3
+ 35.3
+ 36.1
+ 78.7
+ 72.0
+ 37.1
+ 57.2
* 73.3
+ 45.S
* 24.6
* 32.3
* 21.6
* 53.2
+ 65.5

+ 42.5
+ 40.9
+ 78.7

0 0.. : ... ........... :.. .............
*....... ............3
S li.6 1.42 : 35.1
: 5 ......... .............
45.1 1.55 47.0
S 49.. : 1.72 : 358.6
S 33.5 : 1.52 :.............
.............. : 2.81 : 23.7
: 33.0 : 1.77 : 27.6

: 21.6 : 1.74 : 25.9
47.4 : 1.78 : 29.1

: 24.1
: 29.0
S 25.0
: 23.5

: 20.?

.... . .... ,,.. ,,
. .

Z V 26415 F

Table 4.--Effe-ct of c .'.leteness f r)l .ace.ment of cell.solv. by :.:
upon_ the r'etardation of the shri.:-:.;:, and swelling occurrin.' drinA
4-,oeek cycles between 30 and 'JO percent re, ltiv hur. i dly

: IIU'bcr of : eight of wax :Retardlation
Treat iC; ;.iateria:l : dis'dill-,- or oil in wood of shrink-hi
: tions per unit weiht an u .lliT,
: :of wood

Beeswaz. .... ....... ........ 0 il25 10.6
Do.................. . . 1 1.47
Do ....... ............ 2 1.61 4 4
Do. ..... 9 1.60 7.7

Linseed oil.................' 0 1.41 9 7
Do . . ............ ...... 18 7
Do.............. : 1.76 25 9
Do. ........... ... ... . 4 2.04 4

75 percent linseed oil, 2t
percent rosin ........... .: 0 1.46 27,4
75 percent linseed oil, 25
percent rosin............ : 1 1.69 41.5
75 percent linseed oil, 25 :
percent rosin .........: 2 1.5 5.8
75 percent linseed oil, 25 :
percent ro,3in..............: 4 2.12 L3.2

R 1062

T>.1e 5,-m- i ec *at- .L 1oICKs with solutions ot 'axe" d%1 *vd n
-> ;' ^ i-. l. .. t ,;p ,, ", ', .' %, 3'. L~ :|'r-][ '.i v --,*-:? "!.l **- -j ; *
__-.- ,' 'l .. .I.. *r-.. .i. Ve . .. .t--

: ;Concen- `: "ight of wax : .etardation of
Solvent : Treattno material : tratlon : or oil irn wood s "I ";ing
: by per unit : and
; weight : weight of wood : swelling

: : Percent Percent
Cellosolve......... :Paraffln ........ ........ ..: 25 0.43 2,7
Do............... ................... .. 50 9.5
Do......... . ....:... do. ...... ........... 50 .97 26.5
.. ...... Stearin................... 25 .51 15.1
Do ............... ............ ... : 50 1.00 13.5
.. ............. :Rosin.. ............,,...... 25 .52 112.0
.e. .. , . . .. . ........: 50 1.09 .6

o... ...a...afin 60%, stearrin 25 *51' 15
Do.................. . do.. .".............. 50 153 5

Do...............;Pa.affin 60%, beeswax 400%...: 25 .43 943
S.>... ..... ............................... -0 0 34.

,,, ostu 75%, beeswax 25' ..... 18.*1
..... o S 1.09 34.4

. . . .i. . ii qee oil 50'Y, rosin 25c :
S.eeswax 2f ..............., .44 15.2
DO ... ........... ;...... 60, .s 40 . : 25 ,96 38.0

In 75. L rosin 7 25 .59 : 12.2
. ...... .... : 5.... 0..... : 5, .+ 75 15 1

*-Myi alcohol . S. iiri pine o:.. l .60 9.7
.... .. .... .. ,: . . ., ..,*, .., .. 1.2 13.5
,- ............. ..7_7:o in 5'-. ros in ,
: oee *,, ,,S aa y. 2 *a (,6+ -aa U# '30 1,18
Ac t n . ... + . . ... .1 .+ .+ 75. rosi -,, : ,5 .6 Ir. 7

Bo.t +] .. ,. .O .- ....-. d.... Sl' I . pin o .,. ,. . .. ,+ .- : 01.60 9,.b
__________________ _______ ____ ________:__________-___ _., "- B. 1 ii.ill:l+ll:,ll"i 1ll _X J --I; llI5lr

~ic& ~ca- -

'"- 4





-2 i

SM 26094 F

C C^>

30 90 30 90 30 90

Figure 1.--Volumetric swelling of white pine blocks from the air-dry condition
to different stages of the replacement and direct impregnation processes Aith
stearin and after a series of alternate 2-week exposures to (P) and 30 percent
relative humidities together with the corresponding values for the control.

30 90 30

3 1262 08929 1982