Very Strong Woods

Wood comes in all shapes and sizes with individual characteristics particular to that species of tree or that particular piece of wood. Various authorities have standardized ways in which we can compare and contrast wood samples. Some of the comparisons involve how dense is the wood, how heavy, and its hardness. These comparisons involve a number of measurements. The test of a wood’s hardness is made using Janka hardness testing whereby the pounds of force needed to create an imprint of a steel ball in a section of wood is measured.

The density of wood is calculated by using the formula Density = Weight/Unit Volume. The density of wood is oftentimes compared with the density of water with water having a specific gravity of 1. If a piece of wood is less than 1 it should float in water, greater than 1 it will sink. Measuring the weight of wood involves getting a uniform 1 foot cube of wood, drying it to a standard moisture content, usually 12%, then weighing it.

Obtaining the green weight of wood is another measure. These measurements may not mean much unless you compare them to other species. Generally speaking, the heavier, dense, hard woods are among the strongest woods. With these measurements in mind a list of some of the strongest woods throughout the world compared to woods we have in Frederick County leads to interesting comparisons.

The hardest wood is Quebracho with a Janka hardiness rating of 4,570 foot pounds. In comparison one of the hardest wood we have in North America is Osage orange with a rating of 2,620 foot pounds. Some of the hardest woods found in Frederick County include Osage orange 2,620 foot pounds, Ironwood 1,860 foot pounds, and Hickory 1,820 foot pounds. and Black Locust 1,700 foot pounds The hardness of other common trees include: Hard Maple 1,450 foot pounds, White Oak 1,360 foot pounds, Beech 1,300 foot pounds, Red Oak – 1,290 foot pounds, Black Walnut 1,010 foot pounds, Tulip Poplar 430 foot pounds

The heaviest wood dried to 12% moisture content is Black Ironwood at 84.5 lbs. per cubic foot. Leadwood is 75.8 lbs.ft3. Compare these weights to some of our more common trees: Eastern Ironwood 49 lbs. /ft3, White Oak 48 lbs. /ft3, Hard Maple 45 lbs. /ft3, White Ash 41 lbs. /ft3, Black Walnut 36.75 lbs. /ft3, and Tulip Poplar 29 lbs/ft3.

The density of wood is measured against the density of water, water have a specific gravity of one. Any wood with a density greater than 1 will sink in water. Some of the denser woods include Lignum Vitae 1.05 – 1.26, Quebracho: 1.2 – 1.24, and Texas Mesquite 1.05 – 1.3. The density of some woods found in Frederick County include: Osage Orange .76 - .86, Eastern Ironwood .63 - .79, Hickory .64 - .80, Hard Maple .56 - .71, White Oak .60 - .75, and Beech .53 - .71.

Article by Mike Kay, FCFCDB

Nature note for 2/5/2022