U. S. Department of Agriculture, Forest Serv',
FOREST PRODUCTS LABORATORY
In cooperation with the University of Wisconsin
MILL PRACTICES THAT INFLUENCE
THE OCCURRENCE OF SAP STAIN
IN LUMBER '
By IRA HATFILLD
August 15, 1.935
Digitized by the Internet Archive
MILL PRACTICES THAT iT'L:3:- z T CC-:-T-L O 2PJ]C
OF SAP STAIlN IN LUICDF2
Ira Hatfield, Field Assistant,
Division of Forest Patholog7,- Bureau of Plant Industry,
United States Department of Agriculture, in cooperation
with the Southern Forest Experiment Station, Lew Orleans, La.
Since 1G28 the Division of Forest Patholo-:, of the Dureau of
Plant Industry, in cooperation with the Southern Forest experiment Station,
New Orleans, La., end lmboer mr' nufacturers. has been carrying on e::periments
directed at the prevention of sp- stain in iue and hrrdwood lumt.ber -nd
logs.- At the time this experiment wor Was started, th pine and .ard-
wood manufacturers in tie Gu-lf States and lower Eississippi Vallcy were
suffering serious losses in their lumber d [e to degrade caused by sap
stain end mold fungi.
To date more than 200 chemicals have been tested to determine
their stain-preventive qualities, end tests of other cherica.ls are no-, in
progress, At present the chemicals which are giving best stain control
include borax for hardwood, ethyl mercury chloride (Lionasen) for both
pine and hardwoods, sodium tetrachlorophenolate (Dowicide-) for vhard:woods,
and a mixture of sodi-um tetrachlorophenolate and sodium 2-chloroorthophu- l-
phenolate (Dowicide-P) for pine or hardwoods. Soda. solutions havc been and
are still being used to some extent for pine.
Because of n more critical attitude toward stain occurrence,
enterprising millmen h'-ve taken advanta e of the benefits to be derived
from using preventive measures such as cie.mical treatments. It has b cn
estimated that of the 4-1/2 billion board feet of lumber produced in the
southern region last year, about 1-1/ ? billion or one-third of the totrl
output was chemically treated. Of the 1-1/2 billion treated, tTvo-third,
was estimated to be pine and one-third hardwood.
h purpose of this article is to call the matter of stain
prevention to the attention of mrillmen not using anti-stain treatments,
For pertinent references to literature dealing with the developmi nt
of this work, the reader is r(f'rred to the bibliography, at the e-ld
of this article.
and to point out some of the mill practices which influence the
efficiency of chemical treatments used for sap stain control.
Stain-Free Logs Essential for Production of Bright Lumber
To produce bright lum-ber, the millman must start ,'ith stain-free
logs. No chemical has ben found that can be used practicably to remove
stain once it gets into the wood. It is therefore essential that the logs
be cut into lumnber soon enough after the trees are felled to assure thst
stain is not present in the lu-,ber before it is dipped. :.h allowable
time between tree felling a'nd lumber cutting depends upon such factors
as temperature, moisture conditions, insect activity, and log storage
practices. In warmi, humid weather, stain may be observed within a week
after the tree is felled. Henace an attempt should be made to cut as few
logs as possible in advance of utilization at th, mill. Ewv-n pond
storage cannot bu entirely relied upon to preventt stain if logs are
stored in the pond for long periods. Sprains of the ands of logs with
higher concentrations of the chemicals tlmployed for dipping lumber has
been found to retard stain occurrence where short periods of log store
are necessary. Sjich 'praying is particularly applicable to hardwoods.
Correct Concentration of Dipping .Solution Sho'ld 3e maintained
It will not be possible in this article to discuss the proper
preparation and urge of the dipping solutions. Information on vat
construction and preparation of the chemical solutions can be obtained from
the companies manr:eting the various stain prcvwntives. Hoevver, three
faulty practices arc somtimes found which influence the effectiveness of
the chemical treatments. One is the dilution of the dip belowV the
concentration reco 9ondcd by the manufacturers or distributors. The lowest
concentrations of the dipping solutions at .whiich stain and mold may be
controlled have boon carefully determined by experimental tests, and the
lowest practical concentrations are the ones r comoended. Henace to use
weaker solutions may nullify the purpose for :,aich the dip is used. :h-
second b'- practice is the occasional use of an open steams jet to prevent
ice formation in the vat during cold weather. The addition of steam
materially weaaens the dipping solution and mahes it impossible to maintain
a proper solution strength. A steam pipe, the open and of which i. not in
the vat, can be ar:":. ed to give ad equate winter heating, and will not
reduce the stain-protective value of the dip. t- tiird undesirable
practice is the use of roofless dipping vats. Unrooftd vats are particu-
larly undesirable d .rin rainy periods. Lumber needs the greatest
protection during ra:,iny periods, and to allow the solution to become
weakened with rain water increases the chance for stain.
Delay in DinGiing Lu:mber Shoald dbe Avoided
Experiments have shown that a delay of more than 2 days in
dipping lumz.ier :-;,' nullify any advantage to be derived from a chemical
treatment. If insects are present in the logs at the time of cutting, a
delay of even 2 days may mean that the chemical will not prevent stain.
Stain-producing organisms grow very rapidly during warm, humid weather, a'nd
in less than 3 days they can penetrate so deeply into the ,iood that they
cannot be reached by the chemical. A delayed treatment may rake the rough
lumber appear bright, but the dressed lumber will show that the stain-
producing organisms continued to penetrate the wood.
ROe-saw mills and mills maintaining a concentration yard and
dipping the lumber after it arrives at the yard -ill do well to take
cognizance of the above statements. If the mills cutting the logs can be
induced to use the chemicals properly, the lumber should be dipped at the
time of sawing. Bad roads or other factors sometimes cause a delay in
delivering the lumber to the concentration yard or to re-saw mills, and
during such periods of delay the lumber dipped immediately is far less liable
to stain than that dipped later.
Rain Washing Should Be Avoided as Much as Possible
h: millman must remember that the commonly used lumber dips are
applied in water solutions. Hence, since the chemicals are soluble in water,
their effectiveness will be decreased if proper care is not taken to prevent
their being washed from the lumber surfaces by rain. Buggies along the
green chain often are in thec rain from the time the first board is loaded
onto them until they are filled and hauled into the yard; and at some mills
this may take a couple of days for certain leng-ths of lumber. It may still
be raining when ti same lumber is piled. Under such conditions, some of
the dip may be wx-shed from the boards, and if poor seasoning conditions
follow the piling, stain may occur. Since lumber under such conditions is
already at a disadvantage, it should be piled in a a alner that will be
conducive to the fastest possible drying. This may require thLt on r.\:
d'.;.-, a wider space be left between boards than is left under ordinary
practice at the mill. If low foundations are in use or if random-width
lumber is being piled, a wide central flue i-'*ht be used to improve circu-
lation thrr' h the pile.
Provide Good Pile Covers
All completed lumber piles should be provided with a good cover.
The cover should be elevated sufficiently above the pile to permit proper
movement of air thro-...h the pile. Such a cover should not only top the
piles erected on rainy a''ys but should b a part of te' y pr')'ctice
pile, stating thnt the wind blow.s off the ,le vated covers. Thios diff'iculty
can be overcome `y plain, i. crossr stick over tle cover and tying it to
a lo-er cros:aer ',ith twine, or ....ing ay Iimeonsion material to wit
down the covers. Although a close-fitting cover may neep rain out of t
pile, it likewise tends to prevent air circulation through the pile ,nd
may sometimes aid stain develop:. at.
Ado umate -At i ons, 'll! Elevated, Are
s.e.ntial to Stain Control
Circnloticn of air thIrou. h ald aro und the bottom is essential
for proper movem-ent of moist ir down throu7h the pile. 7hiC calls for t".o
I' d -r
adeouate foundations, properly -nlev-.t-d, and thi oth r is proper radication
of weeds and other ve .ta-ion fro:. aro oui the founUdations.
-. proper heiht for t' fo1udaeitions ;will dep-nd upon the
draina;-e of the> ,s-coni..e:"-,".. yard -nd t style of piin: used. Low yards
require Li *,r fouildations th..n hi.-;h, wll-drained yards, but in any case
the rule to follov is to install fou dations of sficient hci;t to provide
ample space for freoe circulation of air undi sl pa -rts of t, pil
,-ncrally spcakinj, vhi,:n solf-crossin--- is the style of pilin '-ised, -raater
ventilation is required tlin w-hen na.rrow crosser sticks ar used. It .i lht
be well to mention here t-iat poor yard sanitation in connection with crosser
sticks can also "be there case of delayed stasonin and conseqcnict st-in.
,-,en the sticl-s are carelessly tnrov'n around t. pile fod-idations, they
not only stop air circul action, bout elso increased. fire azard Und t
chances for deca-y a.d stain in the stickers. Provisions shold be ,de
for piling- te stickers either in the yard or i n store s hedo.
Proper Pile Aline.. ent Allo--ws ,ltter Air Circulation in the Y'ard
Thuas far, in s-e- in v of e ntilaxtion ,:e _iv mentioned only the
ventilation of individual lumoer piles. Since changes are1 :md& fro::. time
to time in the lay-out cf yards at pcrmane:t mills, and since portb11 mills
often set up temporary drying ya-rds, a word should be said aLout t.e yard
lay-out. seasoJlnin yard should be plAnned so a-s t provide for
unobstructed alleys on all sides of the pile.; th"ro-hout y-rd. Hence
there should be alinmrient of the; piles not only in front but lon the
sides and in the roar. Stagig, ercd pil!es and narrow, unleve rea' alley
materially decrease th'j rate of loss of water lre. th drying vard.
Chcmiical treatments have been devise-C th'at are aiding soitho rn
manufacturers in producing l=ubcr relatively free from sap stain. Certain
yard and seasoning practices mrust be observed if full benefit is to bo
derived from the use of these dips:
1. I.Iaiintain a supply of stain-free logs. Do everything practical
to avoid having felling crev; cut far in advance of the mil's capacity to
utilize the logso
2. Do not dilute the dipping solution below the recommended
strength, and do not allow dilution from steal or rain. Provide the vat
with a roof.
3. Dip the 1 inber immediately after sa..",_ or within 2 days at
4. As the dipe;;in' solutions are water-soluble, prevent rain
washing by using ade&ate pile covers, and provide extra chalices for drying
of the lumber in piles erected in the rain.
5t Adeniate pile foun-dations, properly elwvrted, should be
provided-d, rd the ventila; ion thus provided should not be obstructed with
weeds or other vegeotatien or -ith crosser sticks.
U. d drying yard should be laid out with wide front and rear
alleys, and a reasonably wide spacing between piles should be provided. The
foundations should be arran ged so thbat the piles will be in alinemtnt rather
than staggered. This will allow better yard ventilation a
Bi li i orah
(1) Chaupman, A. Dale, -.nd S1. effr, C.
1S3). _.. chemical tr'eatmcn-ts for the control of sap stain and
.mold in u.t.h.. n p+in and hardwood ,r. Southern
Lumeman Ilo (iI): )-30, illus.
(2) Hirrison, G. T
1502. Com itte on sap stalin control. Reports on pro6ros: of
federl s1ap stain control vo'b IT.othern Lumr-n -
(184l): .j-6.1;' ilLis.
(3) Lindgren, R, M.
lo Sap, traio and -iold control at otlrn cill. Southrn
LL ujcr.kan 136 (17i3): 3O, 62, illus. Lumber -r .de Jouarnal
bo (C): 2>-30, illaso
1 S' oration cf loes in stora'oe and its preventions
S>thor ; :. -"n 135 (177'): 4-; illucv. Luiuber Irae
...... ,l N ( ;. ,)20.
(5) _____.7__ -. lph :.
-. ). '* *** rvy ep, ri nts on co t--l cf c '.t st, in -ind mold
i _. -':. n p-i.e, and sap "I-7 bo, -c.:iical tri c.::nt. LmrbLr
I"1.e J 'na!i (7 (c): 2;-2L, illto
---5 Lt:' l of sapi> stain and nold in southern p-ine >nd cap
g''.. preliminary e:pk ri-ments on control by che .iicl treatment.
Southern Lujberman i33 (1779): 62, 64, illus.
(7) _____ __ _____
1-'b Te control of sap stain in southern pin d a snd sap u.m.
A..rican L"'ocz-.rxn 2. 7: ","-47, ills.
1 3* t vention of detcricration in stored logs by chemical
ra~ tment. L-mber Trade JSu'nal 38 (9): 37-38. South rn
;...... eri;..a.. l l (1753): 250.
(9) ______________ ,nd Chapman, A. Dale
131. Progress in the use of chemical treat t.. ents. to protect
;to)red Io s from deterioration. Al. rica.nL ulberman- n 226:
,6 --, illus. Southern Lumberman 145 (1lCj): TFY,-7o S>
(10) Lindgren, ph I., and Choman, A. Dale
1931. Use of chemical treatment; to protect stored logs.
Bariel and Box and Pac'. s 3b (1); 27-28 illus.
(Abstracted from Southern Lumberman 143 (1306): 75-7o, C'"
i l las. )
(11) ______ ,, and Scheffer, T. C.
15931. Prevention of sap stain and mold in southern woods by
chemical treatment. Southern Lumber:ian 142 (1796): 42c-4b6,
(12) ______ Ralph M".o, aind Scheffer, Theodore C.
1931. EncouragLing results with chemical treatments for the
prevention of sap stain and mold in southern woods.
Amrican Lumbermman 212: 35-37, illus. (same article as
in Southern Lumberman 142 (1796): 42-46, minus the prelimi-
nwruy test table.)
(13) _______ ., Sceffer, T.C., and Chapman, A. D.
1932. Rce.. t tests of chemical tretntment: for presenting
det c:1 tion in stored logs. Southern Lummberman 145
(1(5,4;: !9-21, illus.
1933 .' '. chemical reatn1 'ior coc'-,i of i'ap stain a-id
^.- ..t.ern lmer. .r-'4r of In- stri. and
'. n -; Cheistry 25 (1) -"7 il-us.
(15) Scheffor, T. C*
1934 D:,.pping for control of sap- stain at small pine sawvmills.
Southern -Luiuberman 149 (1887): 10,-110, ll4-_116) illus.
(16) ___________ and Chapman, A. Do
1934. Dipping tests for control of sap stain, mr.cld, and decay
in southern lLumber and logs. Southern Lmberman 4 (S1):
(17) ___________ and Lindiren, R. i..
1932. Some minor stains of southern pine and hardwood lumber
and logs. Journal of Agricultural Research 45: 233-237, illus.
UNIVERSITY OF FLORIDA
II3 1262 08929 1974III
3 1262 08929 1974