the production of cement-bonded wood wool boards. when banded into a bale form, it is used as an archery backstop, comparable to how a straw bale would be used for the same purpose. If protected from the elements, an excelsior archery backstop can last for many years. If sections of it wear down because of repeated targeting, the bale can be soaked liberally since it then expands and holds water, just like a dry sponge. garden mulches and as a growing medium for hydroponic gardens. Properties Wood wool fibers can be compressed and when the pressure is removed they resume their initial volume. This is a useful property for minimizing their volume when shipping. Due to its high volume and large surface area, wood wool can be used for applications where water or moisture retention is necessary. The width of wood wool fibers varies from 1.5 to 20 mm, while their length is usually around 500 mm (depending on the production process). In the UK there are specifications for dimensions, pH, moisture content and freedom from dust and small pieces, set by British Standard BS 2548 for wood wool for general packaging purposes. This standard was originally issued in 1954 and subsequently re-issued in 1986. When these fibers are bonded with cement or magnesite, bonded wood wool boards are produced. Slabs of bonded wood wool are considered environmentally friendly construction and insulation materials because they do not contain organic binders. Production Excelsior is cut from "bolts" (round, halved, quartered, or otherwise split logs) of poplar (for example aspen), pine, spruce or eucalyptus. For evaporative cooler pads, the dominant source is the aspen. Wood wool can be produced in either horizontal or vertical shredding machines. A possible further processing option is washing, which removes dust. Wood-wool processing may involve drying to reduce moisture in compliance with local requirements, as in the UK. Finally, wood wool can be dyed to produce a variety of colored products. History A different product was once known as "wood wool," as well as "pine needle-wool," or "pine wood-wool." According to E. Littell, it was produced in Breslau, Silesia (today Wrocław, Poland) by von Pannewich, who mentioned that in 1842 five hundred counterpanes made of it were purchased for a hospital in Vienna. The process was chemical and made use of the leaves (needles) of Scots Pine. In England, yet another product known as wood wool was