Cut lumber [German version]

Table of contents

General:
Product information
Packaging
Transport
  Container transport
  Cargo securing


Risk factors and loss prevention:
Temperature Odor
Humidity/Moisture Contamination
Ventilation Mechanical influences
Biotic activity Toxicity / Hazards to health
Gases Shrinkage/Shortage
Self-heating / Spontaneous combustion Insect infestation / Diseases




Product information

Product name

German Schnittholz
English Cut lumber, sawn lumber
French Bois débité / bois de sciage
Spanish Madera grabada
Scientific  
CN/HS number * 44 ff.


(* EU Combined Nomenclature/Harmonized System)



Product description

Cut lumber is the wood trade's name for lumber cut longitudinally, i.e. with its grain.

General information about wood:

Wood mainly consists of elongate, firmly intertwined, microscopically small cells. These cells consist of a cell wall and a cell lumen, as a result of which wood is a pore-filled material primarily consisting of cellulose, hemicellulose, lignin and water.

The following Figure shows the macroscopic structure of wood. In addition to the bark and phloem layers, the soft sapwood layers and the hard heartwood layers can also be distinguished. The soft, light-colored sapwood consists of living cells and transports water and nutrients, processes which occur in the outermost annual rings. The hard heartwood consists of dead cells and is often of a dark color due to the deposition of heartwood substances, such as tannins and colorants, resins and other lumber constituents, as well as storage materials.

Figure 1

Figure 1


In comparison to sapwood, heartwood has a lower water content, is heavier, harder and more durable. Trees with a large proportion of heartwood are known as heartwood trees, for example mahogany, cedar and oak. Sapwood trees which exhibit no difference in color and water content between the inner and outer wood are, for example, birch, willow and lime.

"Dressed" lumber is lumber from which the sapwood has been removed. Sapwood is highly susceptible to insect attack, while heartwood is less so.


Quality / Duration of storage

Knot-free, straight-grained lumber with even, narrow growth rings is preferred for the production of cut lumber.


Intended use

Cut lumber is primarily used as structural lumber. It is also used to produce parquet flooring, boxes, roofing shingles, staves, pencils etc..


Figure

(Click on the Figure to enlarge it.)

Cut lumber

Figure 2



Countries of origin

This Table shows only a selection of the most important countries of origin and should not be thought of as exhaustive.

Europe Sweden, Finland, Russia
Africa Liberia, Ivory Coast, Ghana, Nigeria, Cameroon, Equatorial Guinea, Gabon, Congo, Zaire, Kenya, Tanzania
Asia Malaysia, Singapore, Sumatra, Philippines
America Canada, USA, Honduras, Mexico, Chile, Ecuador, Venezuela, Brazil, Argentina
Australia  


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Packaging

Cut lumber is virtually always shipped in bundles, which are usually held together with steel strapping. Container shipment is rare. The individual bundles have frequently already been sorted into lengths at the sawmill for the final receiver.


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Transport

Symbols

Symbol, general cargo

General cargo



Means of transport

Ship, truck, railroad


Container transport

Container shipments of cut lumber are rare.

Suitable container types are those which are suitable for lo/lo loading, such as open-top containers, flatracks.


Cargo handling

Cut lumber must be protected from moisture (rain, snow etc.) during cargo handling, as there is a consequent risk of mold and fungus growth.

Since cut lumber  is sensitive to mechanical damage, appropriate care must be taken during cargo handling. It is important to use the correct loading and unloading equipment and materials.


Stowage factor

The stowage factor of the various species of wood is directly related to their density. A distinction is drawn between theoretical density and apparent density. Theoretical density is calculated purely on the basis of solid lumber, i.e. as if all cavities within a slab of lumber had been obliterated by compaction. Theoretical density is identical for all species of wood and is 1.50 g/cm3. Apparent density or bulk density is calculated from the weight and the volume of the lumber and differs from species to species in accordance with their differing structure. Comparisons can only be made between types of lumber with an identical water content. Fixed points are a water content of 0% (kiln dry lumber) and 15% (air dry lumber). Lumber is divided into the following categories by density:

very light species < 0.40 cm3
moderately light species 0.41 - 0.50 cm3
light species 0.51 - 0.60 cm3
moderately heavy species 0.61 - 0.70 cm3
heavy species 0.71 - 0.80 cm3
very heavy species > 0.80 cm3


Balsawood with a density of 0.14 - 0.44 g/cm3 is the lightest lumber, while quebracho (1.12 g/cm3), ebony (1.18 - 1.33 g/cm3) and guayac (1.20 - 1.30 g/cm3) are among the very heavy species.


Stowage space requirements

When suitable for such loading, cut lumber is also carried as deck cargo (up to approx. 50% of cargo volume or approx. one third of total cargo).


Segregation

Marker pen/oil crayon, fiber rope/thin fiber nets


Cargo securing

Maritime transport: On ships with a lumber freeboard, the cargo must be loaded and secured in accordance with the International Convention on Load Lines, 1966.

Road transport: Vehicles having a headboard and side walls (stanchions) with sufficient strength and loading capacity must be used. Nonslip material must also be placed under the load and between layers. Gaps in the load are often unavoidable due to the handling methods used and vehicle characteristics (load distribution), so the load must be secured in accordance with anticipated accelerations by direct securing (e.g. tight fit, loop lashing) and/or by frictional securing (e.g. tie-down lashing).

For load securing on road vehicles, see also chapter entitled Cut lumber in the GDV Cargo Securing Manual.


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Risk factors and loss prevention

RF Temperature

Cut lumber requires particular temperature, humidity/moisture and possibly ventilation conditions (SC VI) (storage climate conditions).

Favorable travel temperature range: < 25°C [1]

Splitting of cut lumber carried as deck cargo due to solar radiation and consequent drying-out is relatively rare.


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RF Humidity/Moisture

Cut lumber requires particular temperature, humidity/moisture and possibly ventilation conditions (SC VI) (storage climate conditions).

Designation Humidity/water content Source
Relative humidity 75% [1]
Water content 12 - 18% [1]
Maximum equilibrium moisture content 80% [1]


The adequacy of the packaging of moisture-sensitive tongue and groove lumber, which is shipped from Brazil and West Africa, should be checked regularly at the ports of loading.

Moisture-sensitive shaped lumber must be heat-sealed in PVC film and be protected from external moisture in the port prior to loading.

The lumber "works", i.e. swells as it absorbs moisture and shrinks as it dries (hygroscopicity).

Sorption isotherm

Figure 3


Lumber may be divided into the following water content classes:

Water content Designation
0% Kiln dry lumber
6 - 10% Room dry lumber
10 - 12% Very dry lumber
12 - 15% Air dry lumber
15 - 20% Slightly dry lumber
20 - 25% Green lumber (forest dry)
30 - 33% Fiber saturated lumber
> 33% Water saturated lumber


Fiber saturation means that the cell walls (microsystem) are maximally filled with water, while water saturation means that all lumens (micro- and macrosystem) are maximally filled with water.


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RF Ventilation

Cut lumber requires particular temperature, humidity/moisture and possibly ventilation conditions (SC VI) (storage climate conditions).

If the product is dry for shipment, ventilation is not normally required.

However, if there is a risk of drying or moisture damage, ventilation should be provided. The following ventilation measure is then recommended:

Recommended ventilation conditions: air exchange rate: 6 changes/hour (airing)


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RF Biotic activity

Cut lumber displays 3rd order biotic activity.

Respiration processes are essentially suspended, but biochemical and microbial processes continue.


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RF Gases

No risk.


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RF Self-heating / Spontaneous combustion

No risk.


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RF Odor

Active behavior Cut lumber has a slight, pleasant odor.
Passive behavior Cut lumber is sensitive to penetrating odors.



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RF Contamination

Active behavior Cut lumber does not cause contamination.
Passive behavior When not caused by fungal attack, discoloration may arise due to contact of the lumber with ferrous metals, with other moist lumber of certain species or with ship sweat containing iron. The resultant, usually deep, stains arising by a chemical reaction are bluish gray to inky black and may be confused with "blue stain".



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RF Mechanical influences

Mechanical damage may occur during loading of cut lumber due to breakage, splitting or severe pressure and result in depreciation. Incorrect handling and excessive mechanical stresses may snap the strapping (metal strapping, wires etc.).

Sand blown on or into the stack on the quayside before loading may be pressed into the surfaces during subsequent tight storage on board, resulting in considerable damage which cannot be removed by remachining.

Bundled cut lumber is easily damaged during loading and unloading by the use of inadequate or unsuitable gear:

Only electrically powered forklift trucks may be used for stowing or unloading on board, as oil contamination is otherwise inevitable.
Loading and unloading gear must be made from wide nylon belts. Metal straps damage the outer layers of the bundles.
Preslung bundles must be provided with sufficiently wide steel strapping to avoid notching.


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RF Toxicity / Hazards to health

No risk.


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RF Shrinkage/Shortage

Losses of volume may occur due to breakage.


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RF Insect infestation / Diseases

Insect infestation: Infestation with wood-destroying insects is not restricted to transport operations. New infestation or reinfestation occurring during transport may originate from other already infested lumber, but this is difficult to establish. No successful countermeasures are possible during storage on board. In several countries of origin, particularly susceptible wood species are treated with chemical agents as a precaution on felling, but complete protection is not achieved.

Fungal attack: New attack by coloring fungi or further development of existing fungi, which is subsequently usually described as "blue stain", may result in considerable quality degradation during transport. The same applies to new attack and further development of existing wood-destroying fungi; in this case, the change in appearance is frequently described as "white and brown pocket rot". Light-colored lumbers are at the highest risk. Fungal growth during maritime transport generally leaves visible damage subject to the following conditions:

susceptibility of wood species (including sapwood)
water content in lumber, relative to dry weight, between 20% and almost complete saturation
temperatures above 10°C


In order to prevent damage of this kind, susceptible cut lumber is adjusted to a moisture content insufficient to support growth by air drying or kiln drying. Only superficial overdrying to below 20%, in which the water content within the lumber remains at a high level, or chemical treatment by spraying or dipping protect only the surface and are not generally capable of preventing internal "blue stain" which is only revealed on conversion of the lumber. If the moisture content of a previously dried fungus-sensitive lumber rises back to above 20%, e.g. due to rain during loading or dripping sweat on board, the risk of fungal development rises again at temperatures above 10°C because fungal spores are present on virtually all lumber. In properly dried lumber, i.e. lumber with a moisture content of below 15%, atmospheric humidity alone cannot raise the lumber's water content to the level necessary for fungal growth.

Inspection of the lumber during unloading is the only opportunity to determine the location at which blue stain has arisen and developed. Moisture during transport primarily has an impact on the periphery of the stowage block.


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