Janka hardness test

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Janka hardness test.jpg

The Janka hardness test measures the resistance of a sample of wood to denting and wear. It measures the force required to embed an 11.28mm (.444 in) steel ball into wood to half the ball's diameter. This method leaves an indentation. A common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring.

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".

The results are stated in various ways, which can lead to confusion, especially when the name of the actual units employed is often not attached. 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). Sometimes the results are treated as units, for example "660 Janka".

The Janka Hardness test results tabulated below were done in accordance with ASTM D 1037-12 testing methods. Lumber stocks tested ranges from 1" to 2" thick. The tabulated Janka Hardness numbers are an average. There is a standard deviation associated with each species, but these values are not given. It is important to note no testing was done on actual flooring. Other factors affect how flooring performs: the type of core for engineered flooring such as pine, HDF, poplar, oak, 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.

Janka Hardness
Species Janka Hardness (pounds-force)
Australian Buloke
5,060([1])
Schinopsis balansae / Quebracho Colorado / Red Quebracho
4,570([2])
Lignum vitae / Guayacan / Pockenholz
4,500
Patagonian Rosewood / Curupay / Angico Preto / Piptadenia Macrocarpa / Brazilian Tiger Mahogany
3,840
Snakewood / Letterhout / Piratinera Guinensis
3,800
Brazilian Olivewood
3,700
Brazilian Ebony
3,692
Ipê / "Brazilian Walnut" / Lapacho
3,684
African Pearlwood / Moabi Sometimes: Brazilian Cherry "Lite"
3,680
Grey Ironbark
3,664
Bolivian Cherry
3,650
Lapacho
3,640
Cumaru / "Brazilian Teak" sometimes: "Brazilian Chestnut," "Tiete Chestnut," "South American Chestnut," "Southern Chestnut"
3,540
Ebony
3,220
Brazilian Redwood / Paraju / Massaranduba
3,190
Yvyraro
3,040
Bloodwood
2,900
Red Mahogany, Turpentine
2,697
"Southern Chestnut"
2,670
Spotted Gum
2,473
Brazilian Cherry / Jatoba
2,350
Mesquite
2,345
"Golden Teak"
2,330
Santos Mahogany, Bocote, Cabreuva, Honduran Rosewood
2,200
Pradoo
2,170
continued
Species Janka Hardness (pounds-force)
Brazilian Koa
2,160
Sucupira sometimes "Brazilian Chestnut" or "Tiete Chestnut"---------------------------------------------------------------------------------------
2,140
Brushbox
2,135
Osage Orange
2,040


References[edit]

  1. ^ Johnny W. Morlan. "Wood Species Janka Hardness Scale/Chart By Common/Trade Name A - J". The World's Top 125 Known Softest/Hardest Woods. Retrieved 20 December 2011. 
  2. ^ "The Wood Database". 

External links[edit]