Janka hardness

A measure of the hardness of wood, produced by a variation on the Brinell hardness test. The test measures the force required to push a steel ball with a diameter of 11.28 millimeters (0.444 inches) into the wood to a depth of half the ball’s diameter (the diameter was chosen to produce a circle with an area of 100 square millimeters). In Janka's original test, the results were expressed in units of pressure, but when the ASTM standardized the test (tentative issue in , standard first formally adopted in ), it called for results in units of force.

The results are stated in various ways in different countries, which can lead to confusion, especially since the name of the actual unit employed is often not attached. In the United States, the measurement is in pounds-force. In Sweden it is apparently in kilogram-force (kgf), and in Australia, Janka hardness ratings are either in newtons (N) or kilonewtons (kN). Sometimes the results are treated as units, e.g., “360 janka.”

The hardness of wood usually varies with the direction of the grain. If testing is done on the surface of a plank, with the force exerted perpendicular to the grain, the test is said to be of “side hardness.” Side hardnesses of a block of wood measured in the direction of the tree's center (radially), and on a tangent to the tree's rings (tangentially), are typically very similar. End testing is also sometimes done (that is, testing the cut surface of a stump would be a test of end hardness). The side hardness of teak, for example, is in the range 3730 to 4800 newtons, while the end hardness is in the range 4150 to 4500 newtons.

The most common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring.

Notes on the table

The pale blue background indicates species growing in North America. Common names are unreliable since two or more species often have the same common name. We show the common name preferred by the Forest Products Laboratory. Except as noted, all samples were tested at 12% moisture content, typical of air-dried wood. Wood varies; a sample picked at random is expected to have a side hardness between about 80% and 120% of the value shown. Blank cells occur where a wood is sold commercially but so far we have found no hardness data.

Side Hardness of Some Woods Common name Scientific name side hardness,

Janka test,

at 12% moisture content kilonewtons pounds-force afrormosia Pericopsis elata 6.9 1560 albarco Cariniana spp. 4.5 1020 alder, red Alnus rubra 2.6 590 alder, white Alnus rhombifolia andiroba Carapa guianensis 5.0 1130 angelin Andira inermis 7.8 1750 angelique Dicorynia guianensis 5.7 1290 anime Protium spp. 920 apple Malus sylvestris 7.7 1730 ash, black Fraxinus nigra 3.8 850 ash, blue Fraxinus quadrangulata 9.0 2030 ash, green Fraxinus pennsylvanica 5.3 1200 ash, oregon Fraxinus latifolia 5.2 1160 ash, pumpkin Fraxinus profunda 4.4 990 ash, white Fraxinus americana 5.9 1320 aspen, bigtooth Populus grandidentata 1.9 420 aspen, quaking Populus tremuloides 1.6 350 avodire Turraeanthus africanus 4.8 1080 azobe Lophira alata 14.9 3350 baldcypress Taxcodium distichum 2.3 570 balsa Ochroma pyramidale banak Virola spp. 2.3 510 basswood, American Tilia americana 1.8 410 basswood, Carolina Tilia caroliniana basswood, white Tilia heterophylla beech, American Fagus grandifolia 5.8 1300 benge Guibourtia arnoldiana 7.8 1750 birch, gray Betula populifolia 3.4 760 birch, paper Betula papyrifera 4.0 910 birch, river Betula nigra birch, sweet Betula lenta 6.5 1470 birch, yellow Betula alleghaniensis 5.6 1260 boxelder Acer negundo 3.2 720 bubinga Guibourtia spp. 12.0 2690 buckeye, Ohio Aesculus glabra buckeye, yellow Aesculus octandra 1.6 350 buckthorn, cascara Rhamnus purshiana 4.6 1040 bulletwood Manilkara bidentata 14.2 3190 butternut Juglans cinerea 2.2 490 buttonwood Conocarpus erectus catalpa, northern Catalpa speciosa 2.4 550 catalpa, southern Catalpa bignonioides 2.4 550 cativo Prioria copaifera 2.8 630 cedar, Alaska Chamaecyparis nootkatensis 2.6 580 cedar, atlantic white Chamaecyparis thyoides 1.6 350 cedar, Port Orford Chamaecyparis lawsoniana 3.2 720 cedar, yellow Cupressus nootkatensis 2.6 580 ceiba Ceiba pentandra 1.1 240 chalviande Virola spp. 481 cherry, black Prunus serotina 4.2 950 chestnut, American Castenea dentata 2.4 540 chinkapin, giant Castanopsis chrysophylla 3.2 730 coffeetree, Kentucky Gymnocladus dioicus 6,2 1390 cottonwood) balsam poplar Populus balsamifera 1.3 300 cottonwood, black Populus trichocarpa 1.6 350 cottonwood, eastern Populus deltoides 1.9 430 courbaril Hymenaea courbaril 10.5 2350 cuangare Dialyanthera spp. 1.7 380 cypress, Mexican Cupressus lustianica 2.0 460 degame Calycophyllum candidissimum 8.6 1940 determa Ocotea rubra 2.9 660 dogwood, flowering Cornus florida 9.6 2150 Douglas-fir, coast Pseudotsuga menziesii 3.2 710 Douglas-fir, interior west Pseudotsuga menziesii 2.9 660 Douglas-fir, interior north Pseudotsuga menziesii 2.7 600 Douglas-fir, interior south Pseudotsuga menziesii 2.3 510 ekop Tetraberlinia tubmaniana elder, blue Sambucus cerulea 3.7 840 elm, american Ulmus americana 3.7 830 elm, cedar Ulmus crassifolia 5.9 1320 elm, rock Ulmus thomasii 5.9 1320 elm, slippery Ulmus rubra 3.8 860 elm, winged Ulmus alata 6.8 1540 fir, balsam Abies balsamea 1.8 400 fir, California red Abies magnifica 2.2 500 fir, grand Abies grandis 2.2 490 fir, noble Abies procera 1.8 410 fir, pacific silver Abies amabilis 1.9 430 fir, subalpine Abies lasiocarpa 1.6 350 fir, white Abies concolor 2.1 480 goncalo alves Astronium graveolens 9.6 2160 greenheart Chlorocardium rodiei 10.5 2350 hackberry Celtis occidentalis 3.9 880 hackberry, netleaf Celtis reticulata (hackberry) sugarberry Celtis laevigata hemlock, eastern Tsuga canadensis 2.2 500 hemlock, mountain Tsuga mertensiana 3.0 680 hemlock, western Tsuga heterophylla 2.4 540 hickory, bitternut Carya cordiformis hickory, black Carya texana hickory, nutmeg Carya myristicaeformis hickory, pecan Carya illinoensis 8.1 1820 hickory, sand Carya pallida hickory, water Carya aquatica hickory. mockernut Carya tomentosa 8.8 1970 hickory, pignut Carya glabra 9.5 2140 hickory, shagbark Carya ovata 8.4 1880 hickory, shellbark Carya lacinosa 8.1 1810 holly, American Ilex opaca 4.5 1020 honeylocust Gleditsia triacanthos 7.0 1580 hophornbeam, eastern Ostrya virginiana 8.3 1860 hornbeam, American Carpinus caroliniana 7.9 1780 hura Hura crepitans 2.4 550 ilomba Pycnanthus angolensis Exell 2.7 610 incense-cedar Libocedrus decurrens 2.1 470 ipe Tabebuia spp., lapacho group 16.4 3680 iroko Chlorophora spp. 5.6 1260 jarrah Eucalyptus marginata 8.5 1910 jelutong Dyera costulata 1.7

(@15%) 390 juniper, alligator Juniperus deppeana 5.2 1160 juniper, western Juniperus occidentalis kaneelhart Licaria spp. 12.9 2900 kapur Dryobalanops spp. 5.5 1230 karri Eucalyptus diversicolor 9.1 2040 kempas Koompassia malaccensis 7.6 1710 keruing Dipterocarpus spp. 5.6 1270 larch, western Larix occidentalis 3.7 830 laurel, California Umbellularia californica 5.6 1270 laurel, mountain Kalmia latifolia 8.0 1790 lignumvitae Guaiacum spp. 20.0 4500 limba Terminalia superba 2.2 490 locust, black Robinia pseudoacacia 7.6 1700 macawood Platymiscium spp. 14.0 3150 madrone, Pacific Arbutus menziesii 6.5 1460 (magnolia) cucumber tree Magnolia acuminata 3.1 700 magnolia, southern Magnolia grandiflora 4.5 1020 (magnolia) sweetbay Magnolia virginiana mahogany, African Khaya spp. 3.7 830 mahogany, true Swietenia macrophylla 3.6 800 manbarklak Eschweilera spp. 15.5 3480 manni Symphonia globulifera 5.0 1120 maple, bigleaf Acer macrophyllum 3.8 850 maple, black Acer nigrum 5.2 1180 maple, red Acer rubrum 4.2 950 maple, silver Acer saccharimum 3.1 700 maple, sugar Acer saccharum 6.4 1450 marishballi Lincania spp. 15.9 3570 merbau Intsia spp. 6.7

(@15%) 1500 mersawa Anisoptera spp. 5.7 1290 mesquite Prosopis spp. mora Mora spp. 10.2 2300 oak, black Quercus velutina 5.4 1210 oak, cherrybark Quercus falcata var pagodifolia 6.6 1480 oak, southern red Quercus falcata 4.7 1060 oak, laurel Quercus laurifolia 5.4 1210 oak, northern red Quercus rubra 5.7 1290 oak, pin Quercus palustris 6.7 1510 oak, scarlet Quercus coccinea 6.2 1400 oak, shumard Quercus shumardii oak, water Quercus nigra 5.3 1190 oak, willow Quercus phellos 6.5 1460 oak, bur Quercus macrocarpa 6.1 1370 oak, chestnut Quercus prinus 5.0 1130 oak, live Quercus virginiana oak, overcup Quercus lyrata 5.3 1190 oak, post Quercus stellata 6.0 1360 oak, swamp chestnut Quercus michauxii 5.5 1240 oak, swamp white Quercus bicolor 7.2 1620 oak, white Quercus alba 6.0 1360 obeche Triplochiton scleroxylon 1.9 430 okoume Aucoumea klaineana 1.7 380 opepe Nauclea diderrichii 7.3 1630 osage orange Maclura pomifera 9.1

(green) 2040

(green) ovangkol Guibourtia ehie para-angelim Hymenolobium excelsum 7.7 1720 parana-pine Araucaria augustifolia 3.5 780 pau marfim Balfourodendron riedelianum peroba de campos Paratecoma peroba 7.1 1600 peroba rosa Aspidosperma spp., peroba group 7.7 1730 persimmon, common Diospyros virginiana 10.2 2300 pilon Hyeronima spp. 7.6 1700 pine, Caribbean Pinus caribaea 5.5 1240 pine, eastern white Pinus strobus 1.7 380 pine, jack Pinus banksiana 2.5 570 pine, Jeffrey Pinus jeffreyi 2.2 500 pine, limber Pinus flexilis 1.9 430 pine, loblolly Pinus taeda 3.1 690 pine, lodgepole Pinus contorta 2.1 480 pine, longleaf Pinus palustris 3.9 870 pine, ocote Pinus oocarpa 4.0 910 pine, pinyon Pinus edulis 3.8 860 pine, pitch Pinus rigida 2.8 620 pine, pond Pinus serotina 3.3 740 pine, ponderosa Pinus ponderosa 2.0 460 pine, Monterey Pinus radiata 3.3 750* pine. red Pinus resinosa 2.5 560 pine, sand Pinus clausa 3.3 730 pine, shortleaf Pinus echinata 3.1 690 pine, slash Pinus elliotti pine, spruce Pinus glabra 2.9 660 pine, sugar Pinus lambertiana 1.7 380 pine, Table Mountain Pinus pungens 2.9 660 pine, virginia Pinus virginiana 3.3 740 pine, western white Pinus monticola 1.9 420 piquia Caryocar spp. 7.7 1720 primavera Tabebula donnell-smithii 2.9 660 pulgande Dacryodes spp. 666 purpleheart Peltogyne spp. 8.3 1860 ramin Gonystylus bancanus 5.8 1300 redcedar, eastern Juniperus virginiana 4.0 900 redcedar, southern Juniperus silicicola 2.7 610 redcedar, western Thuja plicata 1.6 350 redwood, old growth Sequoia sempervirens 2.1 480 redwood, second growth Sequoia sempervirens 1.9 420 robe Tabebul spp., roble group 4.3 960 rosewood, Brazilian Dalbergia nigra 12.1 2720 rosewood, Indian Dalbergia latifolia 14.1 3170 sajo Campnosperma panamensis 425 sande Brosimum spp., utile group 4.0 900 santa maria Calophyllum brasiliense 5.1 1150 sapele Entandrophragma cylindricum 6.7 1510 sassafras Sassafras albidum 2.8 630 sepetir Pseudosindora palustris 6.3 1410 serviceberry Amelanchier spp. 8.0 1800 shorea Shorea spp., baulau group 7.9 1780 (shorea) dark red meranti Shorea spp., lauan-meranti group 3.5 780 (shorea) light red meranti Shorea spp., lauan-meranti group 2.0 460 (shorea) white meranti Shorea spp., lauan-meranti group 5.1

(@15%) 1140 (shorea) yellow meranti Shorea spp., lauan-meranti group 3.4 770 silverbell, Carolina Halesia carolina 2.6 590 sourwood Oxydendrum arboreum 4.2 940 Spanish-cedar Cedrela spp. 2.7 600 spruce, black Picea mariana 2.3 520 spruce, Engelmann Picea engelmanni 1.7 390 spruce, red Picea rubra 2.2 490 spruce, Sitka Picea sitchensis 2.3 510 spruce, white Picea glauca 2.1 480 sucupira Bowdichia spp. sucupira Diplotropis purpurea 9.5 2140 sumac, staghorn Rhus typhina 3.0 680 sweetgum Liquidambar styraciflua 3.8 850 sycamore, american Platanus occidentalis 3.4 770 tamarack Larix laricina 2.6 590 tanoak Lithocarpus densiflorus teak Tectona grandis 4.4 1000 tornillo Cedrelinga cateniformis 870

(green) tree-of-heaven Ailanthus altissima 7.7 1731 tulapueta Osteophloeum platyspermum 512 tupelo, black Nyssa sylvatica 3.6 810 tupelo. water Nyssa aquatica 3.9 880 wallaba Eperua spp. 9.1 2040 walnut, black Juglans nigra 4.5 1010 white-cedar, northern Thuja occidentalis 1.4 320 willow, black Salix nigra witch hazel Hamamelis virginica 6.8 1530 yellow poplar Liriodendron tulipifera 2.4 540 yew. Pacific Taxus brevifolia 7.1 1600

*Authorities differ significantly on the hardness of Pinus radiata, with published values as high as 792 lbs-force (3.5 kilonewtons) and as low as 625 lbf (2.8 kN).

sources

Forest Products Laboratory.

Wood Handbook: Wood as an Engineering Material.

Technical Report FPL-GTR-113.

Madison, WI: U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, .

Downloadable from www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.pdf See also the 2010 edition, which is downloadable chapter by chapter. Hardness information is in chapter 5.

Harry A. Alden

Hardwoods of North America.

General Technical Report FPL-GTR-83.

Madison, WI: U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, .

Downloadable from www.fpl.fs.fed.us/publications/fplgtr83.pdf

Harry A. Alden

Softwoods of North America.

General Technical Report FPL-GTR-102.

Madison, WI: U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, .

Downloadable from www.fpl.fs.fed.us/publications/fplgtr102.pdf

B. Alan Bendtsen and Martin Chudnoff.

Properties of Seven Columbian Woods.

USDA, Forest Service, Forest Products Laboratory Research Note FPL-0242

Madison, WI: Forest Products Lab,

Martin Chudnoff.

Tropical Timbers of the World.

Agriculture Handbook 607.

Madison, WI: U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, .

Downloadable from www.fpl.fs.fed.us/publications/chud_total.pdf

David W. Green, Marshall Begel and William Nelson.

Janka Hardness Using Nonstandard Specimens.

Research Note FPL-RN-0303.

Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, .

Wayne C. Lewis.

Hardness Modulus as an Alternate Measure of Hardness to the Standard Janka Ball for Wood and Wood-Base Materials.

USDA, Forest Service, Forest Products Laboratory Research Note FPL-0189

Madison, WI: Forest Products Laboratory,

Michael C. Wiemann and David W. Green.

Estimating Janka Hardness from Specific Gravity for Tropical and Temperate Species.

USDA, Forest Service, Forest Products Laboratory Research Paper FPL-RP-643

Madison, WI: Forest Products Laboratory, .

Downloadable from www.fpl.fs.fed.us/documnts/fplrn/fpl_rn303.pdf

resources

Standards:

ASTM D1037-99. Standard Test Methods for Evaluating Properties of Wood-Base Fiber and Particle Panel Materials.

ASTM D143-94(2000)e1 Standard Methods of Testing Small Clear Specimens of Timber.

ISO 3350:1975. Wood–Determination of static hardness.

ISO 3351:1975. Wood–Determination of resistance to impact indentation.

Janka hardness ratings can also be found at sites selling flooring, such as:

www.wflooring.com/Technical_Info/Species_Tech_Info/species_hardness.htm

www.zoltanfloors.com/tech.html

Some information sources say or imply, incorrectly, that Janka hardness is measured in units of pressure, such as pounds per square inch, and that side hardness is a synonym for Janka hardness.

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Last revised: 29 August 2018.