Sticker Sta in in One-inch Red Alder Lumber
By
B. G. Anderson
V
R. G. Frashour
Report No. D-3
April 1954
OREGON FOREST PRODUCTS LABORATORY
State Board of Forestry and School of Forestry,
Oregon State College, Cooperating
Corvallis
STICKL STAIg li! CNE-LCH hED ALI2R LUEI
by
B. G. Anderson
R. G. Frashour
INTRODUCTIOI\
The Oregon Forest Products Laboratory was asked in July 1953 by the
Oregon Alder and Maple Company, Willamina, to work on the problem of dark
'
stain which developed at sticker crossings in air-drying red alder (Alnus
rubra, Bong.) during the surrmer months.
Previous experience at the Oregon Alder and Maple Company had
derncnstrated that the uniform light-brown shade preferred by furniture
manufacturers could be obtained by kiln-drying the lurber inediately after
sawing, using a high initial humidity and an initial dry-bulb temperature
from 130 to 150 degrees F.
It was observed that the color of the lumber when kilndried green
could be varied from nearly wh2,te to chocolate brown by maniulation of the
relative hui4dity and dry-bulb temperature during the first hours (approxiI niately 48) in the kiln.
Lumber handled in this manner did not cevelop
sticker stain.
This suggested the possibility of fixing the color of the lumber by a
steaming treatment before air-dryinig.
With the elimination of sticker stain
and poor color, favorable air-drying weather could be used to full advantage,
with the possibility of saving from 2 to 4 days kiln time.
Four charges of freshly sawed one-inch alder lumber were first steamed
under various conditions, then air-dried.
out previcus steamir3g, as a control.
A fifth charge was
air-dried
with-
2-
DRYING PROCEDURE
Five charges of approximately 200 fbni each of random-width, rough, one-
inch red alder lumber were driec, surfaced, arid inspected to determine the
effects of the exper1rental treatment on the occurrexce of sticker stain in
the finished lumber.
The type of treatment given to eac:i of the five charges
is indicated in the following table:
Steaming treatment
Chg
1
2
3
4
5
DE1
WB2
Time
Final
avg MC
140
18
136
180
177
18
Not steamed
65
77
89
130
120
94
86
130
120
24
24
Air-drying
Dates
Type of
sticker
7/16-8/3 Soid
7/16-8/3
7/15-8/3
I'
Hollowback
8/7-10/12 Solid
8/7-10/12
Final
avg MC
Kiln-drying
Final
avg NC
DB
WB
145
145
145
3].
8.7
15
180
180
180
31
31
8.0
8.9
16
18
180
180
145
120
4.7
145
120
5.0
15
14
Time
1 Dry bulb.
2 Wet bulb.
After kiln drying, charges 1, 2 and 3 were taken to the Oregon Alder
arid Maple Company for planing and inspection.
a thickness of 15/16 inches.
All 3 charges were surfaced to
All boards iii these three charges were found to
be free from sticker stain.
The color characteristics of tie five charLes after final kiln-drying
are summarized as follows:
-3-
Charge
Color
Pattern
1
Light-brown
Uniform
None
Desirable color
2
Flat lightbrown
lJnif'orin
None
Lusterless; undesirable
3
White to pink
Mottled
None
Undesirable color
Similar to
charge 3
Somewhat
mottled
None
"
"
Lighter than
charge 4
Slightly
mottled
In 18% of
boards
I,
II
Sticker stain
Remarks
If
Boards in charge 1 were colored to a uniform light-brown color with no
mottling.
The shade of
o1or in charge 1 was said to conform with the desires
of California furniture manufacturers.
Boards in charge 2 wore colored to a uniform liht-brown color of lighter
shade than that in charge 1.
The shade of color in charge 2 was said to fit the
term "lifeless" or "without luster", as described by floyd Edmiston, of the
Oregon Alder and i'iaple Company.
Boards with a shade of color found in charge
2 are said to be undesirable from the furniture raanufacturers' standpoint.
The difference in color shade or luster between charges 1 and 2 was attributed
to the difference in steaming temperature.
Boards in charge 3 were free from sticker stain, but contained irregular
areas stained in a mottled pattern.
from white to pink.
The background color in these boards was
Color in charge 3 was unsatisfactory for exposed parts
in furniture manufacture.
Charges 4 and 5 were surfaced at
the
Laboratory after kiln-drying, and
inspected for sticker stain.
Charge 4 was free frothi sticker stain, but contained slight not';ng of
color.
Colcr in this charge was similar to that of
charge 5 contained
was lighter than that of
t.ekor stain in l
he.
charge 3,
per cent of
4. and also had less mot
-4-
During the inspection of surfaced boards in charges 1 and 2, an improvement was noted in appearance of tight knots.
Tight knots in these charges
appeared to have suffered less checking during seasonin
and machining than
was observed in the commercial lumber currently being run.
This difference
was tentatively attributed to the steaming treatment given the experimental
lumber before air drying.
Subsequent adjustment in initial kiln-schedule
conditions resulted in confirration of this observation in commercial runs.
The schedule adjustment made was a change in initial wet-bulb depression from
10 deg F to 5 deg F.
Figures 1 through 5 show the progress of air-drying in th various
charges of lumber.
All charges air-dried to an average of about 20 per cent
moisture content in ten days.
Charges 1 through 3 air-dried to an average of
about 15 per cent moisture content in 18 days.
All charges were put out for
air-drying in July or August.
after air-drying, charges 1 through 3 were kiln-dried to an average of
8-9 per cent moisture content in about 30 hours (Figures 6,7, 8
Charges
4 and 5 were kiln--dried to an average of 8-9 per cent moisture content in about
40 hours, although these two charges were left in the kiln for a total of 120
hours (Figures 9, 10).
Charges 1, 2, and 3 were kiln-dried together, as also were charges
and 5.
4
As can be seer; from the drying rates of the kiln samples for the sep-
arate charges (Figures 6, 7, 8, 9, 10), the charges in each group drted in much
the saxre manner, regardless of differences in treatment before kiln-drying.
Figure 11 shows average shrinkage in width during drying for kiln samples
in all charges.
Average shrinkage was 4.5 per cent to an average moisture
content of 10 per cent.
Average shrinkage was 5,1 per cent to an average
moisture content of 7 per cent.
-5-
Fiure 12 gives a cumulative distribution of final moisture-meter rea&
ings in charges 1, 2 and 3.
7.0 and. 11.5 per cent.
All the boards gave mcisture-meter readings between
Ninety-five per cent of the boirds gave readings below
10 per cent, and 80 per cent of the bord gave readins below 9.0 per cent.
The average moisture-meter readin
was 8.
per cent.
The averaçe final moisture
content after conditioning of the kiln samples used in the three chres was
8.5 per cent by the oven-tent method.
Figure 13 gives a cumulative distribution of shrinkage in width of 18
kiln samples dried, to an average of 7.7 per cent moisture content (before conditioning).
The average shrinkae value ws 4.9 per cent.
of the shrinkage values were 5.5 per cent or lower.
Iiriety por cent
Eighty per cent of the
shrinkage values were 5.2 per cent or lower.
C0CLUE IC']5
-
The occurrence of sticker stain during air.dryin, of oi.e-inch red alder
lumber could be elimnated by a steaming treatment of the stickered lumber prior
to air-drying.
A desirable and unifcrm shade of color in the final dried lumber
cn be obtained by the use of this preliminary steaming treatment.
The optimum
conditions fcr this treatment appear to be about 140 deg F dry-bulb te:perature,
4 dee, F wet-bulb depression, and minimum steaiing time abcut 18 hours.
No
doubt, adjustments in the shade of color could be obtained by using different
dry-bulb temperatures and wet-bulb depressions during steaminE.
The immediate
objective of this short-term project was to determine the effects of certain
preliminary treatments on the development of sticher stain durin
air-drying.
The limited data obtained in this study do not permit exact observations on
the color shades resulting frorr various steaming conditions.
The preceeding
conclusions are based on the assumption that the lumber will be freshly sawed
when subjected to the steaming treatment.
-6-
Following the method outlined will allow the operator to take full
advantage of air-drying during the sunrer irionths, with no losses from sticker
staining or undesirable color, and with reduction of 2-4 days in total kiln
tiri:e needed.
100
80
60
40
AvRG: OF SIX PICS
20
0
4
12
8
1
20
TINE, DAYS
Figure 1.
ioisturo content during air-drying of one-inch rod alder
lumber after steaming at 140-136 degrees F for 18 hours; July 6 to
Au,ust 3, 1953.
H
(charge 1)
100
80
0
p1
... 60
uGH
00
40
AVERAGE OF SIX FIECLS
Es
C.')
--
20
-
LOW
00
---
-
4
-
12
- -- - - a-
--,,--
16
20
TLE, DAYS
Figure 2. Moisture content during air-drying of one-inch red alder
lumber after steaming at 180-177 degrees F for 18 hours; July 16
to August 3, 1953.
(charge 2)
10
0
0
IH'AEAEO
I
04
Cl)
ICSF_
0
8
4
12
1
20
TII, DAYS
Figure 3. Moisture content during air- drying of one-inch red alder
lumber not steamed, but stacked on hollow-back stickers from
July 15 to August 3, 1953.
(charge 3
T
8C
0
0
L
040
HIGH
E-1
Cl)
AVERAGE OF SIX PIECES
0
20
------
LOW
0
0
10
20
30
40
50
60
TIME, DAYS
i.gure 4. Moisture content during airdrying of one-inch red alder lumber
after steaming at 130-.130 degrees F for 24 hours; August 7 to October 12, 1953.
(charge 4)
10
0
6c
HIGH
0
0
0 811
20
20
10
30
40
50
--60
TIME, DAYS
Figure 5. Moisture content during air.-dryirg of oneinch red alder lumber
after steaming at 120-120 degrees F for 24 hours; August 7 to October 12,
(charge 5)
200
180
DRY BULB
175
rx 16
150
WET BULB
125
20
HIGH
AVERAGL CF SIX
PICIS
.-
LOW
0
10
20
40
30
TIME, HOURS
Figure 6. Kiln schecu1e-dryin rate for one-inch air-dried
red alder lumber; charge 1.
50
1953.
200
DRY BULB
-
175
l65
WETBULB
¶12
125
20
NIGH
AVEBAGE OF LIX
PIOES
LOW
10
20
40
30
TIME, HOURS
Figure 7. Kiln schedule-drying rate for one-inch
air-dried red alder lumber; charge 2.
0
200
i4
DRY BULB
180
175
165
j
E-s
WET BULB
0
125
.
h
(Jj
20 I
HIH
1
OF CIX
--:
PIECS
10
5
00
10
20
30
40
TIME, HOURS
Figure 8. Kiln schedule-drying rate for one-inch
air-dried red alder lumber; charge 3.
200
180
175
DRYBULB
.161
150
4IJ.5
wI
125
20
15
HIGH
N
z
0
AVAGE OF SIX PIECES
10
N
LCW
0
20
40
60
go
100
120
TflvFT, HCURS
Figure 9. Kiln schedule-drying rate for one-inch air-dried red alder
lumber; charge 4.
200
DRYBULE
1 F()
.161
E-1
150
145
WET BULE
0
125
z
20
I
HIGH
15
1R GE 02 SIX PIECES
l0
0
20
40
4
60
80
100
TIME. HOURS
Figiire 10.
Ki.ln schedule-drying rate for one-inch air-.dried red alder
lumber; charge 5.
120
0
0
20
40
60
80
100
AVERAGE MOISTURE CONTENT, PER CENT
Figure 11. Average shrinkage in width during drying of one-inch
red alder lumber.
100
:i.00
C)
213 BOARDS
13 BOARDS
REPREE ENED
AVG REA.DIr[G:
REPRESEFTD
AVG ShRINGE:!
N
0.0-t fo'
r
"5
C.)
t
4.9 %
0
150
25
0
7
8
10
11
9
12
MOISTURE METER READING, PER CENT
Figure l. Cumulative distribution of
O
final moisture meter readings of
one-inqh red alder; char,es 1, 2,
3.
H--
6
4
7
SHRINKAGE, PER CENT
Figure 13. Cumulative distribution
of shrinkage values in one-inch
red alder lumber dried to 7.7 %
avg mc;
'een-weight basis.