WOODWORKING PROCESSES  

 

Jon K. Parish

 

 

For the purposes of this article, the processes of the woodworking industry will be considered to start with the reception of converted timber from the sawmill and continue until the shipping of a finished wood article or product. Earlier stages in the handling of wood are dealt with in the chapters Forestry  and Lumber industry.

 

The woodworking industry produces furniture and a variety of building materials, ranging from plywood floors to shingles. This article covers the main stages in the processing of wood for the production of wooden products, which are machine working of natural wood or manufactured panels, assembly of machined parts and surface finishing (e.g., painting, staining, lacquering, veneering and so on). Figure 86.1 is a flow diagram for wood furniture manufacturing, which covers nearly the whole range of these processes.

 

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Figure 86.1     Flow diagram for wood furniture manufacturing

 

 

 

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Drying. Some furniture manufacturing facilities may purchase dried lumber, but others perform drying onsite using a drying kiln or oven, fired by a boiler. Usually wood waste is the fuel.

 

Machining. Once the lumber is dried, it is sawed and otherwise machined into the shape of the final furniture part, such as a table leg. In a normal plant, the wood stock moves from rough planer, to cutoff saw, to rip saw, to finish planer, to moulder, to lathe, to table saw, to band saw, to router, to shaper, to drill and mortiser, to carver and then to a variety of sanders.

 

Wood can be hand carved/worked with a variety of hand tools, including chisels, rasps, files, hand saws, sandpaper and the like.

 

In many instances, the design of furniture pieces requires bending of certain wooden parts. This occurs after the planing process, and usually involves the application of pressure in conjunction with a softening agent, such as water, and increased atmospheric pressure. After bending into the desired shape, the piece is dried to remove excess moisture.

 

Assembly. Wood furniture can either be finished and then assembled, or the reverse. Furniture made of irregularly shaped components is usually assembled and then finished.

 

The assembly process usually involves the use of adhesives (either synthetic or natural) in conjunction with other joining methods, such as nailing, followed by the application of veneers. Purchased veneers are trimmed to correct size and patterns, and bonded to purchased chipboard.

 

After assembly, the furniture part is examined to ensure a smooth surface for finishing.

 

Pre-finishing. After initial sanding, an even smoother surface is attained by spraying, sponging or dipping the furniture part with water to cause the wood fibres to swell and “raise”. After the surface has dried, a solution of glue or resin is applied and allowed to dry. The raised fibres are then sanded down to form a smooth surface.

 

If the wood contains rosin, which can interfere with the effectiveness of certain finishes, it may be derosinated by applying a mixture of acetone and ammonia. The wood is then bleached by spraying, sponging or dipping the wood into a bleaching agent such as hydrogen peroxide.

 

Surface finishing. Surface finishing may involve the use of a large variety of coatings. These coatings are applied after the product is assembled or in a flat line operation before assembly. Coatings could normally include fillers, stains, glazes, sealers, lacquers, paints, varnishes and other finishes. The coatings may be applied by spray, brush, pad, dip, roller or flow-coating machine.

 

Coatings can be either solvent based or water based. Paints may contain a wide variety of pigments, depending on the desired colour.

 

Hazards and Precautions

 

Machining safety

Woodworking manufacturing has many of the hazards to safety and health that are common to general industry, with a much larger proportion of extremely hazardous equipment and operations than most. Consequently, safety requires constant attention to safe work habits by employees, vigilant supervision, and maintenance of a safe work environment by employers.

 

Although in many instances woodworking machinery and equipment may be purchased without the necessary guards and other safety devices, it is management’s responsibility to provide adequate safeguards before such machinery and equipment is used. See also the articles Routing machines andWood planing machines.

 

Sawing machines. Employees should be made aware of the safe operating practices necessary for the proper use of various woodworking saws (see figure 86.2 and figure 86.3). Specific guidelines are as follows:

 

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Figure 86.2     Band saw

 

 

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Figure 86.3     Table saw

 

 

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1. When feeding a table saw, hands must be kept out of the line of the cut. No guard can prevent a person’s hand from following the stock into the saw. When ripping with the fence gauge near the saw, a push stick or suitable jig must be used to complete the cut. See figure 86.4.

 

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Figure 86.4     Push sticks

 

 

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2. The saw blade must be positioned so as to minimize its protrusion above the stock; the lower the blade, the less chance for kickbacks. It is good practice to stand out of the line of the stock being ripped. A heavy leather apron or other guard for the abdomen is recommended.

3. Freehand sawing is always dangerous. The stock must always be held against a gauge or fence. See figure 86.3.

4. The saw must be appropriate for the job. For instance, it is an unsafe practice to rip with a table saw not equipped with a non-kickback device. Kickback aprons are recommended.

5. The dangerous practice of removing a hood guard because of narrow clearance on the gauge side can be avoided by clamping a filler board to the table between the gauge and the saw and using it to guide the stock. Employees must never be permitted to bypass guards. Combs, featherboards (see figure 86.5) or suitable jigs must be provided where standard guards cannot be used.

 

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Figure 86.5    Featherboards and combs

 

 

 

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6. Crosscutting long boards on a table saw should be avoided because the operator is required to use considerable hand pressure near the saw blade. Also, boards extending beyond the table may be struck by people or trucks. Long stock should be crosscut on a swing pull saw or radial arm saw with adequate supporting bench.

7. Work that should be done on special power-feed machines should not be done on general-purpose hand-fed machines.

8. To set a gauge of a table saw without taking off the guards, a permanent mark should designate the line of cut on the table top.

9. It is considered safe practice to bring equipment to a complete stop before adjusting blades or fences, and to disconnect the power source when changing blades.

10. A brush or stick should be used to clean sawdust and scrap from a saw.

 

A table saw is also called a variety saw because it can perform a wide variety of sawing functions. For this reason the operator should have a variety of guards, because no one guard can protect from every function. See figure 86.3.

 

Cutting machines. Cutting machines can also be hazardous if not adequately guarded and always used with respect and alertness. Cutting tools should be kept well sharpened and correctly balanced on their spindles.

 

The router shown in figure 86.6 has a brush guard. Other routers may have a ring guard, a round guard that encircles the router bit. The purpose of guards is to keep the hands away from the cutting bit. Computer numerical controlled (CNC) routers may have several bits and are high production machines. On CNC machines the operator’s hands are kept further from the bit area. However, another problem is the high amount of wood dust. See also the article “Routing machines”.

 

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Figure 86.6     Router

 

 

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Guarding on a jointer or surface planing machine is mainly to keep the operator’s hands away from the revolving knives. The “mutton chop”-type guard allows only the portion of the knives which are cutting the stock to be exposed (see figure 86.7). The exposed portion of the knives behind the fence should also be guarded.

 

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Figure 86.7     Jointer

 

 

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The shaper is a potentially very dangerous machine (see figure 86.8). If the shaper knives become separated from the above and below collars on the arbor, they can be thrown with great force. Also, stock must often be held close to the knives. This holding must be done with a fixture instead of by the operator’s hands. Featherboards can be used to hold the stock down against the table. Ring or saucer guards should be used whenever possible. A saucer guard is a round, flat, plastic disk that is mounted horizontally on the arbor above the shaper knives.

 

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Figure 86.8     Shaper

 

 

 

 

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A lathe should be guarded by a hood guard because there is a danger of the stock being thrown from the machine. See figure 86.9. It is good practice for the hood to be interlocked with the motor so the lathe cannot be run unless the hood guard is in place.

 

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Figure 86.9     Lathe

 

 

 

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A ripsaw should have anti-kickback fingers installed to prevent the stock from reversing its direction and striking the operator. See figure 86.10. Also, the operator should wear a padded apron to lessen the impact if a kickback does occur.

 

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Figure 86.10     Ripsaw

 

 

 

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Because the radial arm saw blade can be tilted sideways, a guard must be used which will not lie into the blade. See figure 86.11.

 

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Figure 86.11      Radial arm saw

 

 

 

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Sanding machines. Machined stock pieces are sanded down using belt, jitterbug, disc, drum or orbital sanders. Nip points are created in sanding belts. See figure 86.12. Often these nip points can be guarded with a hood which will also be part of a dust exhaust system.

 

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Figure 86.12   Sander

 

 

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Machine guarding. Figure 86.13 illustrates that the opening between a guard and the point of contact must be decreased as the distance decreases.

 

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Figure 86.13     Distance between guard and point of operation

 

 

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Miscellaneous machine safety concerns. Care must be taken that the use of stock-clamping/holding devices do not create additional hazards.

 

Most woodworking machines create the necessity of the operator (and helper) wearing eye protection.

 

It is common practice for employees to blow dust off of themselves with compressed air. They should be cautioned to keep air pressure below 30 psi and to avoid blowing into eyes or open cuts.

 

Wood dust hazards

Machines that produce wood dust should be equipped with dust-collecting systems. If the exhaust system is inadequate to dispose of the wood dust, the operator may need to wear a dust respirator. The International Agency for Research on Cancer (IARC) has now determined that “there is sufficient evidence in humans for the carcinogenicity of wood dust”, and that “Wood dust is carcinogenic to humans (Group 1)”. Other studies indicate that wood dust may prove an irritant to the mucous membranes of the eyes, nose and throat. Some toxic woods are more actively pathogenic and may produce allergic reactions and occasionally pulmonary disorders and systemic poisoning. See table 86.1.

 

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Table 86.1    Poisonous, allergenic and biologically active wood varieties

 

Scientific names

Selected commercial names

Family

Health Impairment

 

Abies alba Mill (A. pectinata D.C.)

Silver fir

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Acacia spp.

A. harpophylla F. Muell.

A. melanoxylon R. Br.

A. seyal Del.

A. shirley Maiden

Australian blackwood

Mimosaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

 

Acer spp.

A. platanoides L.

Maple

Aceraceae

Dermatitis

 

Afrormosia elata Harms.

(Pericopsis elata Van Meeuwen)

Afrormosia, kokrodua, asamala, obang, oleo pardo, bohele, mohole

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Afzelia africana Smith

A. bijuga A. Chev. (Intsia bijuga A. Cunn.)

A. palembanica Bak. (Intsia palembanica Bak.)

Doussie, afzelia, aligua, apa, chanfuta, lingue merbau, intsia, hintsy

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Agonandra brasiliensis Miers

Pao, marfim, granadillo

Olacaceae

Dermatitis

 

Ailanthus altissima Mill

Chinese sumac

Simaroubaceae

Dermatitis

 

Albizzia falcata Backer

A. ferruginea Benth.

A. lebbek Benth

A. toona F.M. Bail

Iatandza

 

 

Kokko, siris

Mimosaceae

Dermatitis; conjunctivitis-rhinitis; asthma;

toxic effects

 

Alnus spp.

A. glutinosa Gaertn.

Common alder

Black alder

Betulaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Amyris spp.

A. balsamifera L.

A. toxifera Willd.

Venezuelan or West Indian sandalwood

Rutaceae

Dermatitis; toxic effects

 

Anacardium occidentale L.

A. excelsum Skels.

Cashew

Anacardiaceae

Dermatitis

 

Andira araroba Aguiar. (Vataireopsis araroba Ducke)

A. coriacea Pulle

A. inermis H.B.K.

Red cabbage tree

 

Partridge wood

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Aningeria spp.

A. robusta Aubr. and Pell.

A. altissima Aubr. and Pell.

Antiaris africana Engl.

A. welwitschi Engl.

Aningeria

 

Antiaris, ako, chen chen

Sapotaceae

 

Moraceae

Conjunctivitis-rhinitis; asthma

 

Toxic effects

 

Apuleia molaris spruce (A. leiocarpa MacBride)

(A. ferrea Mart.)

Redwood

Caesalpinaceae

Dermatitis; toxic effects

 

Araucaria angustifolia O. Ktze

A. brasiliana A. Rich.

Parana pine, araucaria

Araucariaceae

Toxic effects

 

Aspidosperma spp.

A. peroba Fr. All.

A. vargasii A. DC.

Red peroba

 

Pau marfim, pau amarello, pequia marfim, guatambu, amarilla, pequia

Apocynaceae

Dermatitis; conjunctivitis-

rhinitis; asthma; toxic effects

 

Astrocaryum spp.

Palm

Palmaceae

Dermatitis; toxic effects

 

Aucoumea klaineana Pierre

Gabon mahogany

Burseraceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis

 

Autranella congolensis

A. Chev. (Mimusops congolensis De Wild.)

Mukulungu, autracon, elang, bouanga, kulungu

Sapotaceae

Dermatitis

 

Bactris spp. (Astrocaryum spp.)

Palm

Palmaceae

Dermatitis; toxic effects

 

Balfourodendron riedelianum Engl.

Guatambu, gutambu blanco

Rutaceae

Dermatitis

 

Batesia floribunda Benth.

Acapu rana

Caesalpinaceae

Toxic effects

 

Berberis vulgaris L.

Barberry

Berberidaceae

Toxic effects

 

Betula spp.

B. alba L. (B. pendula Roth.)

Birch

Betulaceae

Dermatitis

 

Blepharocarva involucrigera F. Muell.

Rosebutternut

Anacardiaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Bombax brevicuspe Sprague

B. chevalieri Pell

Kondroti, alone

Bombacaceae

Dermatitis

 

Bowdichia spp.

B. nitida Benth.

B. guianensis Ducke (Diplotropis guianensis Benth.)

(Diplotropis purpurea Amsh.)

Black sucupira

Papilionaceae

Dermatitis

 

Brachylaena hutchinsii Hutch.

Muhuhu

Compositae

Dermatitis

 

Breonia spp.

Molompangady

Rubiaceae

Dermatitis

 

Brosimum spp.

B. guianense Hub. (Piratinera guianensis Aubl.)

Snakewood, letterwood, tigerwood

Moraceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

 

Brya ebenus DC. (Amerimnum ebenus Sw.)

Brya buxifolia Urb.

Brown ebony, green ebony, Jamaican ebony, tropical American ebony

Papilionaceae

Dermatitis

 

Buxus sempervirens L.

B. macowani Oliv.

European boxwood, East London b., Cape b.

Buxaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

 

Caesalpinia echinata Lam. (Guilandina echinata Spreng.)

Brasilwood

Caesalpinaceae

Dermatitis; toxic effects

 

Callitris columellaris F. Muell.

White cypress pine

Cupressaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Calophyllum spp.

C. brasiliense Camb.

Santa maria, jacareuba, kurahura, galba

Guttiferae

Dermatitis; toxic effects

 

Campsiandra laurifolia Benth.

Acapu rana

Caesalpinaceae

Toxic effects

 

Carpinus betulus

Hornbeam

Betulaceae

Dermatitis

 

Cassia siamea Lamk.

Tagayasan, muong ten, djohar

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Castanea dentata Borkh

C. sativa Mill.

C. pumila Mill.

Chestnut, sweet chestnut

Fagaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Castanospermum australe A. Cunn.

Black bean, Australian or Moreton Bay chestnut

Papilionaceae

Dermatitis

 

Cedrela spp. (Toona spp.)

Red cedar, Australian cedar

Meliaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Cedrus deodara (Roxb. ex. Lamb.) G. Don

(C. libani Barrel. lc)

Deodar

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Celtis brieyi De Wild.

C. cinnamomea Ldl.

Diania

Gurenda

Ulmaceae

Dermatitis

 

Chlorophora excelsa Benth. and Hook I.

C. regia A. Chev.

C. tinctoria (L.) Daub.

Iroko, gelbholz, yellowood, kambala, mvule, odum, moule, African teak, abang, tatajuba, fustic, mora

Moraceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis

 

Chloroxylon spp.

C. swietenia A.DC.

Ceylon satinwood

Rutaceae

Dermatitis; toxic effects

 

Chrysophyllum spp.

Najara

Sapotaceae

Dermatitis

 

Cinnamomum camphora Nees and Ebeim

Asian camphorwood, cinnamon

Lauraceae

Toxic effects

 

Cryptocarya pleurosperma White and Francis

Poison walnut

Lauraceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

 

Dacrycarpus dacryoides (A. Rich.) de Laub.

New Zealand white pine

Podocarpaceae

Dermatitis; conjunctivitis-rhinitis; asthma

 

Dacrydium cupressinum Soland

Sempilor, rimu

Podocarpaceae

conjunctivitis-rhinitis; asthma

 

Dactylocladus stenostachys Oliv.

Jong kong, merebong, medang tabak

Melastomaceae

Toxic effects

 

Dalbergia spp.

D. amerimnon Benth.

D. granadillo Pitt.

D. hypoleuca Standl.

D. latifolia Roxb.

D. melanoxylon Guill. and Perr.

D. nigra Fr. All.

 

 

D. oliveri Gamble

D. retusa Hemsl.

D. sissoo Roxb.

D. stevensonii Standl.

Ebony

 

Red foxwood

 

Indian rosewood, Bombay blackwood, African blackwood, pallisander, riopalissandro, Brasilian rosewood, jacaranda

 

Burma rosewood

Red foxwood

Nagaed wood, Honduras rosewood

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma;

toxic effects

Dialium spp.

D. dinklangeri Harms.

Eyoum, eyum

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Diospyros spp.

D. celebica Bakh.

D. crassiflora Hiern

D. ebenum Koenig

Ebony, African ebony

 

Macassar ebony, African ebony, Ceylon ebony

Ebenaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Dipterocarpus spp.

D. alatus Roxb.

Keruing, gurjum, yang, keruing

Dipterocarpaceae

Dermatitis

Distemonanthus benthamianus Baill.

Movingui, ayan, anyaran, Nigerian satinwood

Caesalpinaceae

Dermatitis

Dysoxylum spp.

D. fraseranum Benth.

Mahogany, stavewood, red bean

Meliaceae

dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

D. muelleri Benth.

Rose mahogany

 

 

Echirospermum balthazarii Fr. All. (Plathymenia reticulata Benth.)

Vinhatico

Mimosaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Entandophragma spp.

E. angolense C.D.C.

E. candollei Harms.

E. cylindricum Sprague

E. utile Sprague

Tiama

Kosipo, omo

Sapelli, sapele, aboudikro

Sipo, utile, assiй,

kalungi, mufumbi

Meliaceae

Dermatitis;

allergic extrinsic alveolitis

Erythrophloeum guineense G. Don

E. ivorense A. Chev.

Tali, missanda, eloun, massanda, sasswood, erun, redwater tree

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Esenbeckia leiocarpa Engl.

Guaranta

Rutaceae

Dermatitis

Eucalyptus spp.

E. delegatensis R.T. Back

E. hemiphloia F. Muell.

E. leucoxylon Maiden

E. maculata Hook.

E. marginata Donn ex Sm.

E. microtheca F. Muell.

E. obliqua L. Herit.

E. regnans F. Muell.

E. saligna Sm.

 

Alpine ash

Grey box

Yellow gum

Spotted gum

 

 

 

Mountain ash

Myrtaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Euxylophora paraensis Hub.

Boxwood

Rutaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Excoecaria africana M. Arg. (Spirostachys africana Sand)

E. agallocha L.

African sandalwood, tabootie, geor, aloewood, blind-your-eye

Euphorbiaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Fagara spp.

F. flava Krug and Urb. (Zanthoxylum flavum Vahl.)

F. heitzii Aubr. and Pell.

F. macrophylla Engl.

Yellow sanders, West Indian satinwood, atlaswood, olon, bongo, mbanza

Rutaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Fagus spp. (Nothofagus spp.)

F. sylvatica L.

Beech

Fagaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Fitzroya cupressoides (Molina) Johnston

(F. patagonica Hook. f.)

Alerce

Cupressaceae

Dermatitis

Flindersia australis R. Br.

F. brayleyana F. Muell.

F. pimenteliana F. Muell.

Australian teak, Queensland maple, maple

Silkwood, Australian maple

Rutaceae

Dermatitis

Fraxinus spp.

F. excelsior L.

Ash

Oleaceae

Dermatitis

Gluta spp.

G. rhengas L. (Melanorrhoea spp.)

M. curtisii Pierre

M. laccifera wallichii Hook.

Rengas, gluta

Renga wood

Rhengas

Anacardiaceae

Dermatitis; toxic effects

Gonioma kamassi E. Mey.

Knysna boxwood, kamassi

Apocynaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Gonystylus bancanus Baill.

Ramin, melawis, akenia

Gonystylaceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis

Gossweilerodendron balsamiferum (Verm.) Harms.

Nigerian cedar

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Grevillea robusta A. Cunn.

Silky oak

Proteaceae

Dermatitis

Guaiacum officinale L.

Gaiac, lignum vitae

Zygophyllaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Guarea spp.

G. cedrata Pell.

 

G. laurentii De Wild.

G. thompsonii Sprague

Bossй

Nigerian pearwood Cedar mahogany

Scented guarea

Black guarea

Meliaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Halfordia scleroxyla F. Muell.

H. papuana Lauterb.

Saffron-heart

Polygonaceae

Dermatitis; allergic extrinsic alveolitis

Hernandia spp.

H. sonora L. (H. guianensis Aubl.)

Mirobolan, topolite

Hernandiaceae

Dermatitis

Hippomane mancinella L.

Beach apple

Euphorbiaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Illipe latifolia F. Muell.

I. longifolia F. Muell. (Bassia latifolia Roxb.) (B. longifolia Roxb.)

Moak, edel teak

Sapotaceae

Dermatitis

Jacaranda spp.

J. brasiliana Pers. Syn. (Bignonia brasiliana Lam.)

J. coerulea (I.) Gris.

Jacaranda

 

Caroba, boxwood

Bignoniaceae

Dermatitis

Juglans spp.

J. nigra L.

J. regia L.

Walnut

Juglandaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Juniperus sabina L.

J. phoenicea L.

J. virginiana L.

 

 

Virginian pencil cedar, Eastern red cedar

Cupressaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Khaya antotheca C. DC.

 

K. ivorensis A. Chev.

K. senegalensis A. Juss.

Ogwango, African mahogany, krala

 

Dry-zone mahogany

Meliaceae

Dermatitis; allergic extrinsic alveolitis

Laburnum anagyroides Medic. (Cytisus laburnum L.)

L. vulgare Gris

Laburnum

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Larix spp.

L. decidua Mill.

L. europea D.C.

Larch

European larch

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Liquidambar styracifolia L.

Amberbaum, satin-nussbaum

Hamamelidaceae

Dermatitis

Liriodendron tulipifera L.

American whitewood, tulip tree

Magnoliaceae

Dermatitis

Lovoa trichilioides Harms. (L. klaineana Pierre)

Dibetou, African walnut, apopo, tigerwood, side

Meliaceae

dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Lucuma spp. (Pouteria spp.)

L. procera

Guapeva, abiurana

Massaranduba

Sapotaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Maba ebenus Wight.

Makassar-ebenholz

Ebenaceae

Dermatitis

Machaerium pedicellatum Vog.

M. scleroxylon Tul.

M. violaceum Vog.

Kingswood

Papilionaceae

Dermatitis

Mansonia altissima A. Chev.

Nigerian walnut

Sterculiaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Melanoxylon brauna Schott

Brauna, grauna

Caesalpinaceae

Dermatitis

Microberlinia brazzavillensis A. Chev.

M. bisulcata A. Chev.

African zebrawood

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Millettia laurentii De Wild.

M. stuhlmannii Taub.

Wenge

Panga-panga

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma;

toxic effects

Mimusops spp. (Manilkara spp.)

Mimusops spp. (Dumoria spp.) (Tieghemella spp.)

M. congolensis De Wild. (Autranella congolensis A. Chev.)

M. djave Engl. (Baillonella toxisperma Pierre)

M. heckelii Hutch. et Dalz. (Tieghemella heckelii Pierre

(Dumoria heckelii A. Chev.)

Muirapiranga

Makorй

Mukulungu, autracon

 

Moabi

Cherry mahogany

Sapotaceae

Dermatitis; conjunctivitis-rhinitis; asthma;

allergic

extrinsic alveolitis; toxic effects

Mitragyna ciliata Aubr. and Pell.

M. stipulosa O. Ktze

Vuku, African poplar

Abura

Rubiaceae

Dermatitis; conjunctivitis-rhinitis; asthma;

toxic effects

Nauclea diderrichii Merrill (Sarcocephalus diderrichii De Wild.)

Nauclea trillessi Merrill

Bilinga, opepe, kussia, badi, West African boxwood

Rubiaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Nesogordonia papaverifera R. Capuron

Kotibй, danta, epro, otutu, ovovй, aborbora

Tiliaceae

Toxic effects

Ocotea spp.

O. bullata E. Mey

O. porosa L. Barr. (Phoebe porosa Mez.)

O. rodiaei Mez. (Nectandra rodiaei Schomb.)

O. rubra Mez.

O. usambarensis Engl.

Stinkwood

 

Laurel Brazilian walnut

Greenheart

Louro vermelho

East African camphorwood

Lauraceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Paratecoma spp.

P. alba

P. peroba Kuhlm.

 

Brazilian white peroba

Peroba white. p.

Bignoniaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Parinarium spp.

P. guianense (Parinari spp.) (Brosimum spp.)

P. variegatum

 

Guyana-satinholz

Antillen-satinholz

Rosaceae

Dermatitis

Peltogyne spp.

P. densiflora Spruce

Blue wood, purpleheart

Caesalpinaceae

Toxic effects

Phyllanthus ferdinandi F.v.M.

Lignum vitae, chow way, tow war

Euphorbiaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Picea spp.

P. abies Karst.

P. excelsa Link.

P. mariana B.S.P.

P. polita Carr.

European spruce, whitewood

 

 

Black spruce

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis

Pinus spp.

P. radiata D. Don

Pine

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Piptadenia africana Hook f.

Piptadeniastrum africanum Brenan

Dabema, dahoma, ekhimi

agobin, mpewere, bukundu

Mimosaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Platanus spp.

Plane

Platanaceae

Dermatitis

Pometia spp.

P. pinnata Forst.

Taun

Kasai

Sapindaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Populus spp.

Poplar

Salicaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Prosopis juliflora D.C.

Cashaw

Mimosaceae

Dermatitis

Prunus spp.

P. serotina Ehrl.

Cherry

Blackcherry

Rosaceae

dermatitis; conjunctivitis-rhinitis; asthma

Pseudomorus brunoniana Bureau

White handlewood

Moraceae

Dermatitis; toxic effects

Pseudotsuga douglasii Carr. (P. menziesii Franco)

Douglas fir, red fir, Douglas spruce

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Pterocarpus spp.

P. angolensis D.C.

P. indicus Willd.

P. santalinus L.f. (Vatairea guianensis Aubl.)

African padauk, New Guinea rosewood, red sandalwood, red sanders, quassia wood

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Pycnanthus angolensis Warb. (P. kombo Warb.)

Ilomba

Myristicaceae

Toxic effects

Quercus spp.

Oak

Fagaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Raputia alba Engl.

R. magnifica Engl.

Arapoca branca, arapoca

Rutaceae

Dermatitis

Rauwolfia pentaphylla Stapf. O.

Peroba

Apocynaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Sandoricum spp.

S. indicum Cav.

Sentul, katon, kra-ton, ketjapi, thitto

Meliaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Schinopsis lorentzii Engl.

S. balansae Engl.

Quebracho colorado, red q., San Juan, pau mulato

Anacardiaceae

Dermatitis; toxic effects

Semercarpus australiensis Engl.

S. anacardium L.

Marking nut

Anacardiaceae

Dermatitis; toxic effects

Sequoia sempervirens Endl.

Sequoia, California

redwood

Taxodiaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Shorea spp.

Alan, almon, red balau

White heavy, red lauan, white L., yellow L., mayapis, meranti bakau, dark red M., light red M., red M., white M., yellow M., red seraya, white seraya

Dipterocarpaceae

Dermatitis

S. assamica Dyer

Yellow lauan, white meranti

 

 

Staudtia stipitata Warb. (S. gabonensis Warb.)

Niovй

Myristicaceae

Dermatitis

Swietenia spp.

S. macrophylla King

S. mahogany Jacq.

Mahogany, Honduras mahogany, Tabasco m., baywood, American mahogany,

Cuban mahogany

Meliaceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis; toxic effects

Swintonia spicifera Hook.

S. floribunda Griff.

Merpauh

Anacardiaceae

Dermatitis

Tabebuia spp.

T. ipe Standl. (T. avellanedae Lor. ex Gris.)

T. guayacan Hensl. (T. lapacho K. Schum)

Araguan, ipй preto, lapacho

Bignoniaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Taxus baccata L.

Yew

Taxaceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis; toxic effects

Tecoma spp.

T. araliacea D.C.

T. lapacho

Green heart

Lapacho

Bignoniaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Tectona grandis L.

Teak, djati, kyun, teck

Verbenaceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis

Terminalia alata Roth.

T. superba Engl. and Diels.

Indian laurel

limba, afara, ofram, frakй, korina, akom

Combretaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Thuja occidentalis L.

T. plicata D. Don

T. standishii Carr.

White cedar

Western red cedar

Cupressaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Tieghemella africana A. Chev. (Dumoria spp.)

T. heckelii Pierre

Makorй, douka, okola, ukola, makorй, abacu, baku, African cherry

Sapotaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Triplochiton scleroxylon K. Schum

Obeche, samba, wawa, abachi, African whitewood, arere

Sterculiaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Tsuga heterophylla Sarg.

Tsuga, Western hemlock

Pinaceae

Dermatitis

Turraeanthus africana Pell.

Avodirй

Lusamba

Meliaceae

Dermatitis; allergic extrinsic alveolitis

Ulmus spp.

Elm

Ulmaceae

Dermatitis

Vitex ciliata Pell.

 

Verbenaceae

Dermatitis

V. congolensis De Wild. and Th. Dur

Difundu

 

 

V. pachyphylla Bak.

Evino

 

 

Xylia dolabriformis Benth.

 

Mimosaceae

Conjunctivitis-rhinitis;

X. xylocarpa Taub.

Pyinkado

 

asthma

Zollernia paraensis Huber

Santo wood

Caesalpinaceae

Dermatitis; toxic effects

 

Source: Istituto del Legno, Florence, Italy.

 

___________________________________________________________________________

 

 

Increased use of high-production CNC machinery such as routers, tenoners and lathes creates more wood dust and will require new dust-collection technology.

 

Dust control. Most dust in a woodworking production shop is removed by local exhaust systems. However, often there is a considerable accumulation of very fine dust that has settled on rafters and other structural members, especially in areas where sanding is done. This is a hazardous situation, with great potential for fire and explosion. A flash fire over dust-covered surfaces may be followed by explosions of increasing force. In order to minimize this probability, it would be wise to use a checklist. See sample checklist in box.

 

Assembly hazards

A wide range of adhesives is used in the bonding of veneers to manufactured panels, depending on the characteristics required of the final product. Apart from casein glue, natural adhesives are less widely employed and the greatest use is made of synthetic adhesives such as urea-formaldehyde. Synthetic adhesives may pose a hazard of skin disease or systemic intoxication, especially those which release free formaldehyde or organic solvents into the atmosphere. Adhesives should be handled in well ventilated premises and sources of vapour emission should be equipped with exhaust ventilation. Employees should be provided with gloves, protective creams, respirators and eye protection when necessary.

 

The moving parts, especially blades, of veneer slicing, jointing and clipping machines should be fully guarded. Two-hand controls may be necessary.

 

Finishing hazards

Surface finishing. Solvents used for carrying the sprayed pigments or for thinning can include a wide variety of volatile organic compounds which may reach toxic and explosive concentrations in the air. In addition, many pigments are toxic by inhalation of spray mist (e.g., lead, manganese and cadmium pigments). Wherever dangerous concentrations of vapour or mist can occur, use exhaust ventilation (e.g., spray painting in a booth) or use water sprays. All sources of ignition, including fires, electrical equipment and static electricity, should be eliminated before any operations begin.

 

An active hazardous material communication programme should be in place to alert employees to all hazards created by toxic, reactive, corrosive and/or ignitable finish, glue and solvent chemicals and the protective measures that should be taken. Eating in the presence of these chemicals should be prohibited. Proper storage of flammables and proper disposal of soiled rags and steel wool which could cause spontaneous ignition are imperative.

 

Fire prevention. In view of the highly flammable nature of wood (especially in the form of dust and shavings) and of the other items found in a woodworking plant (such as solvents, glues and coatings), the importance of fire prevention measures cannot be overemphasized. Measures include:

 

· installing automatic wood-dust and shaving collection equipment on saws, planers, moulders and so on, which transport the waste to storage silos pending disposal or recovery

· prohibiting smoking at the workplace and eliminating all sources of ignition (e.g., open flames)

· ensuring regular clean-up procedures of deposited dust and shavings

· adequate maintenance of machines to prevent occurrences such as the overheating of bearings

· installation of fire barriers, sprinkler systems, fire extinguishers, fire hoses and a crew trained to use this equipment

· proper storage of flammables

· explosion-proof electrical equipment where needed.

 

Environmental and Public Health Concerns

The production of finished products from wood can be done without long-range environmental damage. The harvesting of trees can be done in such a manner that new growth can replace what is cut. Major deforestation such as has been the case in rain forests can be discouraged. Waste products from the machining of wood (i.e., sawdust, wood chips) can be used in chipcore or as fuel.

 

While there are solid waste and process wastewater implications for the woodworking industry, the major concerns are the air emissions resulting from the use of waste wood as fuel and from solvent-intensive finishing operations. Wood-fired boilers are commonly used in drying operations, while many of the finishing materials are applied by spray. In both instances, engineering controls are required to reduce air-borne particulates and recover and/or incinerate the volatile compounds.

 

Controls should result in operators being exposed to less toxic chemicals as less hazardous substitutes are found. Use of water-based finishes instead of solvent-based will decrease fire hazards.