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CONTENTS

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27

Introduction

Why the manufacturer seasons his lumber.

Place of seasoning in American Lumber Standards..

Losses incurred in seasoning lumber --

Seasoning of lumber in sawmill yards.

Sawmill yard arrangement and layout.

Pile foundations.-

Width and spacing of lumber piles.--

Experimental tests on foundations.

Pile widths and heights.

Side and rear spacing of lumber piles_-

Pile stickers, and chimneys or tunnels, and spacing between boards..

Projection of end stickers_-

Sorting of lumber for grades, widths, and lengths for piling-

Box piling---

Special piling in pile bottoms..

Pile roofs.

Side piling--

Special pile protection.---

Air seasoning as affected by liability to blue stain.

Defects produced in lumber by air seasoning-

Surface checking and casehardening-

Loosening of knots--

Warping and cupping-

Period required for adequate air-drying of lumber.

Seasoning of miscellaneous sawmill products--

Seasoning of timbers_.

Seasoning of sawed railroad ties--

Air-drying of lath----

Air-drying of small-dimension stock..

The kiln-drying of lumber at the sawmill.

The kiln operator----

Progressive and compartment types of kilns.

Progressive kilns---

Sorting of mill product for drying in progressive kilns.

Drying time in progressive kilns..

Steam-heating equipment of dry kilns.-

Why the final kiln-drying stage needs more heat and less humidity

Compartment kilns for sawmill kiln-drying---

Piling of lumber for kiln-drying-

Stickers and sticking in dry-kiln piling-

Box-piling in kiln loads_--

Common faults in compartment-kiln operation---

Operation of compartment kilns.-

Steaming treatments particularly in compartment kilns---

Kiln-drying of sawmill product other than lumber-

The kiln-drying of shingles.-

Making moisture-content tests---

Casehardening tests and samples.

Dry-kiln control readings and instruments.

Final steaming of kiln-dried stock...

Sawmill shed storage of lumber.

Heated storage---

Kiln-drying in a vacuum.

Bibliography of lumber seasoning, handling, and care for the lumber

manufacturer.

ILLUSTRATIONS

Fig.

1. Scheme of pile and alley numbering for sawmill yard.-

2. New longitudinal pile foundations on concrete piers

3. Old foundation contrasted with improved form.

4. Two views of foundations on concrete piers--

5. Foundations too low and handicapped by weeds---

6. A typical foundation bent.

7. Short lumber piles on longer stringer foundations.

8. Foundation supported on wooden blocks.-

9. Short hemlock piled on double-length foundations -

10. Double-ranked piling of Red River Lumber Co. served by locomotive

crane_-

11. Short hemlock piled two end-lapped lengths to pile.

12. Good and poor care of stickers---

13. Power lumber piler or elevator..

14. "Air-line piling" under monorail ----

15. Portable horse used in piling unit packages.

16. Sling used for lifting unit packages by cable-

17. Straddle lumber tractor-

18. Elevated tramcar helps in piling lumber---

19. Improved jack for elevating lumber to top of pile.

20. Simple sticker spacing frame.

21. Diagram of arrangement of tiers in box piling-

22. Yard alleys showing common form of pile roofs..

23. Cross section of side-piled lumber pile--

24. Pile shield for end of pile of 3-inch cypress.

25. Pole stacking for reduction of blue-stain damage.

26. Samples showing checking and honeycombing-

27. Section of oak plank showing severe honeycomb--

28. End checking in a cross section of western larch.

29. Partly air-dried pile of thick oak with severe end check

30. Warped lumber produced by crooked sticker course_

31. Drying rate chart for Douglas fir----

32. Method of piling railroad ties known as 7-1 or 8-1.

33. Lath loaded for kiln-drying at southern pine sawmill..

34. Round-edged lumber piled for air-drying----

35. Squares bundled with stickers and wire-tied over protecting blocks--

36. Bundle dimension stacked for air-drying outdoors..

37. Piles of squares end protected with heavy paper---

38. Squares shed piled with ends butted to reduce end check-

39. Dimension in large stacks, end lapped----

40. Short lumber piled herringbone fashion without stickers.

41. Air-seasoning yard for stave bolts_

42. Stack of stave bolts showing method of stacking--

43. Proper piling of squares to reduce surface check..-

44. Conventionalized longitudinal section of progressive kiln.

45. Kiln load piled with narrow vertical vents --

46. Kiln load piled with liberal vertical air vents--

47. Kiln load mechanically piled of package units.

48. Convenient form of control chart for progressive kilns.-

49. Conventionalized cross section of compartment kiln.

50. Edge-stacked kiln load collapsed by shrinkage in kiln.

51. Study of two kinds of spacing between boards.

52. Use of form for shaping chimney in kiln load.

53. Completed load piled with use of tunnel form.

54. Kiln load piled with vertical through chimney-

55. Kiln load with flared chimney reaching part way up-

56. Piling frame with sticker spacing racks--

57. Kiln load of redwood piled in sticker frame-

58. Transfer car equipped with tractor power---

59. Method of cutting moisture-test samples.--

60. Recesses in side of kiln load for holding kiln samples.

61. Casehardening samples and what they show---

62. Cupping of casehardened southern pine board upon resawing.

63. Chart of equilibrium moisture content in wood---

NATIONAL COMMITTEE ON WOOD UTILIZATION

R. P. LAMONT, chairman,
R. Y. STUART, Forester, United States Forest Service, Department of Agri-

culture, vice chairman.
AXEL H. OXHOLM, director.
DUDLEY F. HOLTMAN, construction engineer.
EDWARD EYRE HUNT, secretary.

The National Committee on Wood Utilization, established by direction of President Coolidge, comprises over 150 members, representing manufacturers, distributors, and consumers of lumber and wood products. Its object is to work for closer utilization of our country's timber resources. The committee, whose headquarters are in the Department of Commerce, Washington, D. C., works in close cooperation with a number of official and private organizations, notably the Bureau of Standards of the Department of Commerce and the Forest Products Laboratory of the Forest Service, Department of Agriculture.

SUBCOMMITTEE ON SEASONING, HANDLING, AND CARE OF LUMBER

B. F. DULWEBER, president Kraetzer-Cured Lumber Co., Greenwood, Miss.,

chairman. WALTER ROBINSON, vice president Pickering Lumber Co., Kansas City, Mo., vice chairman.

MANUFACTURERS' SUBCOMMITTEE

A. TRIESCHMANN, chairman; Crossett Watzek Gates, Chicago, Ill.
C. R. Johnson, president Union Lumber Co., San Francisco, Calif.
W. M. NICHOLS, resident manager, the Pioneer Lumber Co., Elrod, Ala.
J. M. PRITCHARD, hardwood operating manager, Kirby Lumber Co., Silsbee, Tex.
CARL L. WHITE, president, the Breece White Manufacturing Co., Arkansas

City, Ark.

VII

FOREWORD

Probably no other measure will so greatly increase the usefulness of lumber as its proper seasoning—not only because the seasoned stock is increased in strength from one to three times as compared with green lumber, but also because its lasting qualities are enhanced and charges for freight, and handling costs, are greatly reduced. For this reason modern or efficient wood-utilization practice must have for one of its most important parts efficient methods for the seasoning, handling, and care of lumber. In modern business to-day the old adage “ Check the evil at its source” applies, and particularly in this instance. It is natural and logical that lumber should be seasoned before it leaves the mill, hence the responsibility of the manufacturer in supplying to the consumer, the fabricator, and the distributor well-seasoned stock.

This edition is the fourth of a series of four bulletins covering the seasoning, handling, and care of lumber. The facts and findings are largely based upon the replies to questionnaires sent to manufacturers of practically all the commercial wood species of importance in the United States and represent a summary of the methods which they employ.

This report is intended to point out in a purely suggestive way the various methods of producing properly seasoned lumber. Yard layouts, methods of handling, and yard seasoning are also discussed.

The report has been prepared for the subcommittee by the late Albert Benjamin Cone, of the committee staff. Acknowledgment is made of the valuable services and assistance given by the United States Forest Service through its Forest Products Laboratory; from the Division of Building and Housing, Bureau of Standards; from the Agricultural Engineering Division, Bureau of Public Highways, United States Department of Agriculture; from the National Lumber Manufacturers' Association and its regional organizations; and from all those whose plant facilities were inspected in the field surveys, or who have cooperated in supplying material for questionnaires which form the basis for this report.

Appreciation is also due to C. J. Hogue, Albert Hermann, and Phillips A. Hayward, for their valuable assistance in the compilation of this publication, and to those others who have assisted in criticizing and revising this report.

AXEL H. OXHOLM, Director. APRIL 15, 1929.

SEASONING, HANDLING, AND CARE OF LUMBER FOR

MANUFACTURERS

INTRODUCTION

This report on the seasoning, handling, and care of lumber by the manufacturer is in no sense an instruction manual. There is already a liberal amount of instruction text on various phases of the subject, and the report attempts to review this text and ascertain how far its details are reflected in the general practice of lumber manufacturers. This is imperfectly accomplished, because of the lack of adequate survey of the subject at the mills in the various lumber manufacturing regions; the information used has been secured largely from studies made and reported by others, and chiefly by the experts of the Forest Products Laboratory or other branches of the United States Forest Service, some of them in cooperation with various lumber manufacturers' associations. Considerable additional information has been brought in by replies to questionnaires sent out, for the purpose of securing information for this report, to representative manufacturers in all species of wood and in all lumber-manufacturing regions. These replies give a fair view of the main features of practice in respect to the subjects embraced in the report.

As an adequate personal field survey of the entire sawmill industry was impossible, touch was established with approximately 700 manufacturers by the mailing out of elaborate questionnaires on air-drying and on kiln-drying. There was some misgiving in sending this out because of its size, and had it been simple more would doubtless have taken the time to answer it, but the replies would not so completely have covered the subject. It is a matter of some significance that 73 mills, or a little more than 1 in 10, did return replies, most of them very complete. The mills replying were fairly representative of all the commercial species of lumber and reported an aggregate annual production of 3,231,500,000 feet of lumber, or about 8.3 per cent of the total annual production, or an average of 44,050,000 feet per mill, thus indicating that the largest manufacturers were most strongly represented in the replies received. In one respect this is somewhat unfortunate, in that the information compiled from these replies represents seasoning practice somewhat better and more progressive than the general average used in the industry; but this result could be expected. Those who pay most attention to the subject of seasoning will be most apt to reply to a questionnaire on the subject and also will be most apt to have made most progress in their own seasoning practice.

The effort of the report is to be of use to the individual manufacturer—to offer suggestions which he may test and discard or adopt

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