Janka hardness test

The Janka hardness test (English: /ˈdʒæŋkə/;^[1] German: [ˈjaŋka]), created by Austrian-born American researcher Gabriel Janka (1864–1932), measures the resistance of a sample of wood to denting and wear.^{[citation needed]} It measures the force required to embed an 11.28-millimeter-diameter (7⁄16 in) steel ball halfway into a sample of wood. (The diameter was chosen to produce a circle with an area of 100 square millimeters, or one square centimeter.)^[2]

A common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring. For hardwood flooring, the test usually requires an 80 mm × 150 mm (3 in × 6 in) sample with a thickness of at least 6–8 mm, and the most commonly used test is the ASTM D1037. When testing wood in lumber form, the Janka test is always carried out on wood from the tree trunk (known as the heartwood), and the standard sample (according to ASTM D143) is at 12% moisture content and clear of knots.^[3]

The hardness of wood varies with the direction of the wood grain. Testing on the surface of a plank, perpendicular to the grain, is said to be of "side hardness". Testing the cut surface of a stump is called a test of "end hardness".^{[citation needed]} Side hardness may be further divided into "radial hardness" and "tangential hardness", although the differences are minor and often neglected.

The results are stated in various ways, leading to confusion, especially when the actual units employed are often not attached. The resulting measure is always one of force. In the United States, the measurement is in pounds-force (lbf). In Sweden, it is in kilograms-force (kgf), and in Australia, either in newtons (N) or kilonewtons (kN). This confusion is greatest when the results are treated as units, for example "660 Janka".^[4]

The Janka hardness test results tabulated below followed ASTM D 1037-12 testing methods. Lumber stocks tested range from 1" to 2" (25-50 mm) thick. The tabulated Janka hardness numbers are an average. There is a standard deviation associated with each species, but these values are not given.^{[citation needed]} No testing was done on actual flooring.

Other factors affect how flooring performs: the type of core for engineered floorings, such as pine, HDF, poplar, oak, or birch; grain direction and thickness; floor or top wear surface, etc. The chart is not to be considered an absolute; it is meant to help people understand which woods are harder than others.

Typical Janka hardness values

Key
Hardwood
Softwood
Pseudowood

Typical Janka side hardness

Species	Force: pounds-force (newtons)
Australian Buloke[5]	5,060 lbf (22,500 N)	5060
Schinopsis brasiliensis, Quebracho, Barauna, Chamacoco[6]	4,800 lbf (21,000 N)	4800
Schinopsis balansae, Quebracho Colorado, Red Quebracho[7]	4,570 lbf (20,300 N)	4570
Lignum vitae, Guayacan, Pockholz	4,500 lbf (20,000 N)	4500
Anadenanthera colubrina var. cebil, Curupay, Angico Preto, Brazilian Tiger Mahogany	3,840 lbf (17,100 N)	3840
Snakewood, Letterhout, Brosimum guianense	3,800 lbf (17,000 N)	3800
Brazilian Olivewood	3,700 lbf (16,000 N)	3700
Brazilian Ebony	3,700 lbf (16,000 N)	3700
Ipê, Brazilian Walnut, Handroanthus lapacho	3,684 lbf (16,390 N)	3684
African Pearwood, Moabi	3,680 lbf (16,400 N)	3680
Grey Ironbark	3,664 lbf (16,300 N)	3664
Bolivian Cherry	3,650 lbf (16,200 N)	3650
Lapacho	3,640 lbf (16,200 N)	3640
Sucupira, Brazilian Chestnut, Tiete Chestnut	3,417 lbf (15,200 N)	3417
Kingwood[8]	3,340 lbf (14,900 N)	3340
Dipteryx, Cumaru, Brazilian Teak[9]	3,330 lbf (14,800 N)	3330
Ironwood	3,260 lbf (14,500 N)	3260
Ebony	3,220 lbf (14,300 N)	3220
Massaranduba, Brazilian Redwood, Paraju	3,190 lbf (14,200 N)	3190
Yvyraro	3,040 lbf (13,500 N)	3040
Strand Woven Bamboo	3,000 lbf (13,000 N)	3000
Cocobolo	2,960 lbf (13,200 N)	2960
Bloodwood (Brosimum rubescens)	2,900 lbf (13,000 N)	2900
Boxwood	2,840 lbf (12,600 N)	2840
Olive[10]	2,710 lbf (12,100 N)	2710
Red Mahogany, Turpentine	2,697 lbf (12,000 N)	2697
Live Oak	2,680 lbf (11,900 N)	2680
Southern Chestnut	2,670 lbf (11,900 N)	2670
Spotted Gum	2,473 lbf (11,000 N)	2473
Brazilian Cherry, Jatoba	2,350 lbf (10,500 N)	2350
Mesquite	2,345 lbf (10,430 N)	2345
Golden Teak	2,330 lbf (10,400 N)	2330
Guatambú, Kyrandy, Balfourodendron riedelianum	2,240 lbf (10,000 N)	2240
Santos Mahogany, Bocote, Cabreuva, Honduran Rosewood	2,200 lbf (9,800 N)	2200
Pradoo	2,170 lbf (9,700 N)	2170
Brazilian Koa	2,160 lbf (9,600 N)	2160
Brushbox	2,135 lbf (9,500 N)	2135
Osage Orange[11]	2,040 lbf (9,100 N)	2040
Karri	2,030 lbf (9,000 N)	2030
Sydney Blue Gum	2,023 lbf (9,000 N)	2023
Palmyra Palm	2,020 lbf (9,000 N)	2020
Bubinga	1,980 lbf (8,800 N)	1980
Cameron	1,940 lbf (8,600 N)	1940
Tallowwood	1,933 lbf (8,600 N)	1933
Merbau	1,925 lbf (8,560 N)	1925
Amendoim	1,912 lbf (8,500 N)	1912
Jarrah	1,910 lbf (8,500 N)	1910
Coconut Palm	1,900 lbf (8,500 N)	1900
Purpleheart	1,860 lbf (8,300 N)	1860
Goncalo Alves, Tigerwood	1,850 lbf (8,200 N)	1850
Hickory, Pecan, Satinwood	1,820 lbf (8,100 N)	1820
Afzelia, Doussie, Australian Wormy Chestnut	1,810 lbf (8,100 N)	1810
Castello boxwood	1,810 lbf (8,100 N)	1810
Bangkirai	1,798 lbf (8,000 N)	1798
Rosewood	1,780 lbf (7,900 N)	1780
Apple[12]	1,730 lbf (7,700 N)	1730
African Padauk	1,725 lbf (7,670 N)	1725
Blackwood	1,720 lbf (7,700 N)	1720
Merbau	1,712 lbf (7,620 N)	1712
Kempas	1,710 lbf (7,600 N)	1710
Black Locust	1,700 lbf (7,600 N)	1700
Highland Beech	1,686 lbf (7,500 N)	1686
Red Mulberry	1,680 lbf (7,500 N)	1680
Wenge, Red Pine, Hornbeam	1,630 lbf (7,300 N)	1630
Tualang	1,624 lbf (7,220 N)	1624
Zebrawood	1,575 lbf (7,010 N)	1575
True Pine, Timborana	1,570 lbf (7,000 N)	1570
Peroba	1,557 lbf (6,930 N)	1557
European Yew[13]	1,520 lbf (6,800 N)	1520
Sapele, Sapelli, Kupa'y	1,510 lbf (6,700 N)	1510
Curupixa	1,490 lbf (6,600 N)	1490
Sweet Birch	1,470 lbf (6,500 N)	1470
Hard maple, Sugar Maple	1,450 lbf (6,400 N)	1450
Caribbean Walnut	1,390 lbf (6,200 N)	1390
Kentucky coffeetree	1,390 lbf (6,200 N)	1390
Natural Bamboo (represents one species)	1,380 lbf (6,100 N)	1380
Australian Cypress	1,375 lbf (6,120 N)	1375
White Oak	1,360 lbf (6,000 N)	1360
Tasmanian oak	1,350 lbf (6,000 N)	1350
Ribbon Gum	1,349 lbf (6,000 N)	1349
Ash (White)	1,320 lbf (5,900 N)	1320
American Beech	1,300 lbf (5,800 N)	1300
Red Oak (Northern)	1,290 lbf (5,700 N)	1290
Caribbean Heart Pine	1,280 lbf (5,700 N)	1280
Keruing	1,270 lbf (5,600 N)	1270
Yellow Birch, Iroko	1,260 lbf (5,600 N)	1260
Movingui	1,230 lbf (5,500 N)	1230
Heart pine	1,225 lbf (5,450 N)	1225
Carapa guianensis, Brazilian Mesquite	1,220 lbf (5,400 N)	1220
Larch	1,200 lbf (5,300 N)	1200
Carbonized Bamboo (represents one species)	1,180 lbf (5,200 N)	1180
Teak	1,155 lbf (5,140 N)	1155
Brazilian Eucalyptus, Rose Gum	1,125 lbf (5,000 N)	1125
English Oak[14]	1,120 lbf (5,000 N)	1120
Makore	1,100 lbf (4,900 N)	1100
Siberian Larch	1,100 lbf (4,900 N)	1100
Peruvian Walnut	1,080 lbf (4,800 N)	1080
Boreal	1,023 lbf (4,550 N)	1023
Black Walnut, North American Walnut	1,010 lbf (4,500 N)	1010
Cherry	995 lbf (4,430 N)	995
Black Cherry, Imbuia	950 lbf (4,200 N)	950
Red Maple[15]	950 lbf (4,200 N)	950
Boire	940 lbf (4,200 N)	940
Paper Birch	910 lbf (4,000 N)	910
Eastern Red Cedar, Monkeypod	900 lbf (4,000 N)	900
Southern Yellow Pine (Longleaf)	870 lbf (3,900 N)	870
Lacewood, Leopardwood	840 lbf (3,700 N)	840
African Mahogany	830 lbf (3,700 N)	830
Mahogany, Honduran Mahogany	800 lbf (3,600 N)	800
Parana	780 lbf (3,500 N)	780
Sycamore	770 lbf (3,400 N)	770
Box Elder	720 lbf (3,200 N)	720
Shedua	710 lbf (3,200 N)	710
Radiata Pine[16]	710 lbf (3,200 N)	710
Silver Maple[17]	700 lbf (3,100 N)	700
Southern Yellow Pine (Loblolly and Shortleaf)	690 lbf (3,100 N)	690
Douglas Fir	660 lbf (2,900 N)	660
Western Juniper	626 lbf (2,780 N)	626
Alder (Red)	590 lbf (2,600 N)	590
Larch	590 lbf (2,600 N)	590
Chestnut	540 lbf (2,400 N)	540
Yellow Poplar, Poplar	540 lbf (2,400 N)	540
Hemlock	500 lbf (2,200 N)	500
Western White Pine	420 lbf (1,900 N)	420
Basswood	410 lbf (1,800 N)	410
Eastern White Pine	380 lbf (1,700 N)	380
Western Red Cedar	350 lbf (1,600 N)	350
Cuipo[18]	75 lbf (330 N)	75
Balsa[18]	70 lbf (310 N)	70
Balsa, softest wood ever measured: single unusual example[18]	22 lbf (98 N)	22

References

1. Baldwin, Elizabeth (5 January 2018). "The Scoop on Wood Hardness, Part 1: What is Janka?". hardwoodfloorsmag.com. National Wood Flooring Association. Retrieved 17 April 2021..
2. "Janka hardness". Sizes.com. Retrieved 4 May 2021.
3. "What is the Janka Hardness Scale". Avant Garde Flooring. 10 March 2019. Archived from the original on 15 July 2019. Retrieved 12 September 2019.
4. Pedersen, Jason. "The Janka Hardness Test". Low Cost Flooring. Archived from the original on 15 March 2016. Retrieved 18 March 2016.
5. Morlan, Johnny W. "Wood Species Janka Hardness Scale/Chart By Common/Trade Name A–J". The World's Top 125 Known Softest/Hardest Woods. Morlan wood gifts. Archived from the original on 26 April 2012. Retrieved 20 December 2011.
6. "Global Species".
7. "Quebracho". Lumber identification. The Wood Database. Archived from the original on 2016-03-04. Retrieved 2014-05-22.
8. "Kingwood". Lumber identification. The Wood Database.
9. "Cumaru". Lumber identification. The Wood Database.
10. "Olive". The Wood Database. Archived from the original on 5 June 2023. Retrieved 15 December 2023.
11. "Osage orange". Lumber identification. The Wood Database.^{[permanent dead link]}
12. "Olive". The Wood Database. Archived from the original on 3 June 2023. Retrieved 15 December 2023.
13. "European Yew". The Wood Database. Archived from the original on 8 June 2023. Retrieved 15 December 2023.
14. "English Oak". The Wood Database. Archived from the original on 3 March 2016. Retrieved 28 August 2015.
15. "Wood charts", Custom workshop, archived from the original on 2013-01-06, retrieved 2018-11-30.
16. "Radiata Pine". Lumber identification. The Wood Database. Archived from the original on 2016-08-11. Retrieved 2015-04-04.
17. "Silver Maple". Lumber identification. The Wood Database. Archived from the original on 2016-08-09. Retrieved 2012-02-19.
18. Wiepking, C. A.; Doyle, D. V. (November 1955). "Strength and related properties of Balsa and Quipo woods". UISDA Forest Service, Forest Products Laboratory: 27–28. Report No. 1511. {{cite journal}}: Cite journal requires |journal= (help) The record softness of 22 lbf is often falsely ascribed to quipo, but all such reports appear to be a misreading of figures 15 and 16 from this primary source, which makes clear that measurement is of balsa, and the softest quipo measured was 46 lbf tangential, 38 lbf radial.

External links

• Janka Hardness Scale For Wood – Side Hardness Chart of Some Woods
• USDA – Wood Handbook – Wood as an Engineering Material Archived 2015-11-21 at the Wayback Machine
• USDA – Janka Hardness Using Nonstandard Specimens Archived 2012-12-22 at the Wayback Machine