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The Care and Feeding of White Woods

Tom GraberBaillie Lumber

Smyrna, New York

Bill SmithSUNY ESF

Syracuse, New York

The Care and Feeding of White Woods

Kinds of:• Challenges:

1) Rotation. 2) Color Retention (interior and

exterior)3) Stain (fungal, chemical,

and…) 4) Drying environment (Air

Drying and kilns) 5) Dimensional stability 6) Kiln / boiler limitations 7) Bruising 8) Stick Shadow 9) Mixed loading / MC variation

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The Care and Feeding of White Woods

Kinds of:• Solutions:

1) Fast from tree to thee as fast as possible.

2) Scheduling, winter cut, fast rotation

3) storage, scheduling…4) high airflow, low temp / RH

schedule 5) Cutting, sticking, stacking,

rotation 6) Airflow, heating / venting

capacity 7) Eliminate sawmilling process 8) Breeze dry sticks / dry sticks 9) LCD scheduling

The Care and Feeding of White Woods

Kinds of:• Challenges:

1) Rotation. 2) Color Retention (interior and

exterior)3) Stain (fungal, chemical,

and…) 4) Drying environment (Air

Drying and kilns) 5) Dimensional stability 6) Kiln / boiler limitations 7) Bruising 8) Stick Shadow 9) Mixed loading / MC variation

• Solutions:1) Fast from tree to thee as fast as

possible.2) Scheduling, winter cut, fast

rotation3) storage, scheduling…4) high airflow, low temp / RH

schedule 5) Cutting, sticking, stacking,

rotation 6) Airflow, heating / venting

capacity 7) Eliminate sawmilling process 8) Breeze dry sticks / dry sticks 9) LCD scheduling

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Rotation.

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The Care and Feeding of White Woods

• Rotation – basic steps:1) Winter – Have lumber in the kiln before tree knows it is dead. 2) Spring, Summer, Fall – Have lumber in the kiln before the tree hits

the ground.

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Rotation

Rotation

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Rotation

Rotation, not

Color Retention

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Color Retention

Color Retention

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Color Retention

Color Retention

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Stain

Drying environment

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Drying environment

Drying environment

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Drying environment

Drying environment

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Dimensional stability - stacking

Dimensional stability - stacking

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Dimensional stability - sticking

Dimensional stability - stacking

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Dimensional stability - full courses

Kiln / boiler limitations

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Kiln / boiler limitations

Bruising

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Stick Shadow

Mixed loading / MC variation

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Mixed loading / MC variation

Mixed loading / MC variation

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Some SUNY ESF Laboratory Research

Spectrophotometer Color Analysis

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What is color?

Lab color space

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Schedule, Season, Log Age

Drying SchedulesDrying schedule for 4/4 hard maple T8-C3 (Normal color)

Temperature in degrees F

501301802615 to final

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501101602220 to 156

351151503525 to 205

191211405730 to 254

111191307235 to 303

71231308140 to 352

512513086Above 401

Wet Bulb

Depression

Wet

Bulb

Dry

Bulb

Relative

Humidity (%)

Moisture Content

(%)Step

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Temperature in degrees F

501101602215 to final

7

50901401520 to 156

50801302225 to 205

35851203230 to 254

20901104735 to 303

14961106040 to 352

1010011070Above 401

Wet Bulb

Depression

Wet

Bulb

Dry

Bulb

Relative

Humidity (%)

Moisture Content

(%)Step

Drying SchedulesDrying schedule for 4/4 hard maple T3-C5 (White color)

Spectrophotometer a*b* color values for winter harvested material

10

15

20

25

30

2 4 6 8 10 12a*

b*

T3-C5 -Fresh log T8-C3-Fresh logT3-C5-4wk log T8-C3-4wk logT3-C5-8wk log T8-C3-8wk log

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10

15

20

25

30

2 4 6 8 10 12a*

b*

Summer fresh T3-C5 Summer fresh T8-C3 Summer 4wk T3-C5 Summer 4wk T8-C3 Summer 8wk T3-C5 Summer 8wk T8-C3

Spectrophotometer a*b* color values for summer harvested material

Fresh log

4 wk log

8wk log

Winter Spring Summer

Fresh log

4 wk log

8wk log

WHITE

NORMAL

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Average L* color values

60

65

70

75

80

85

90

L*

Winter Harvested

Summer Harvested

Spring Harvested

Fresh 8 wk log4 wk logFresh 8 wk log4 wk log

T8-C3T3-C5

Fresh log

4 wk log

8wk log

Winter Spring Summer

Air dry

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60

65

70

75

80

85

90

L*

Winter Harvested

Summer Harvested

Spring Harvested

Fresh 8 wk log4 wk log

Average L* color values for air dried material

Interior Color

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Drying days

0.5 1 1.5 2 2.5 3 7 12

@ 90F

Drying days

0.5 1 1.5 2 2.5 3 7 12

@ 110F

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Drying days

0.5 1 1.5 2 2.5 3 7 12

@ 130F

Drying days

0.5 1 1.5 2 2.5 3 7 12

@ 150F

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Temperature (F)

90 110 130 150

After 12 Days

CONCLUSIONS

•Critical temperature to cause interior darkening seems to be around 110 F

•The proof:

1. Interior darkening started immediately with above 130F drying

2. 90F drying did not result with interior darkening.

3. During 110F drying, interior darkening started when core temperature plateaus.

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Past experience ….

Interior darkening developed above FSP.

Not much color change developed below FSP

In this study:

2 days at Core temp. 110 F, AMC 30, Core MC higher than FSP, Darkening has started.

3 days at Core temp. 110F, AMC 20, Core MC is around FSP, Darkening progresses.

5 days at Core temp. 110F, AMC 15, Core MC below FSP,

Darkening ended.

Recommendation

•Keep core temp below 110 F until Core MC is

•below FSP (average MC below 20%)

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Some of our competition...In China

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Thank you!any Question, Comments?