Wood wool is a material made from thin, flexible strands of shaved wood, used primarily for packaging, insulation, and animal bedding. It looks similar to straw but is finer and more uniform, with individual strands as thin as 0.002 inches and as narrow as 1/64 of an inch. In North America, the broader category of shaved wood strands is commonly called “excelsior,” while “wood wool” refers specifically to the finest grades.
How Wood Wool Is Made
The manufacturing process is straightforward. Logs are cut into short bolts and fed into a machine that uses two sets of knives working together. A row of small parallel scoring knives cuts vertical grooves into the face of the wood, setting the width of each strand. Then a slicing knife shaves across the surface, peeling off a thin layer that separates into individual ribbons along those scored lines. The bolt is held between rollers that automatically advance it into the knives with each pass.
Machines come in two designs: upright models where the knives move vertically, and horizontal models where they move side to side. Both produce the same product. Standard excelsior strands are about 18 inches long, 0.01 inches thick, and range from 1/26 inch wide (fine) to 7/32 inch wide (coarse). Wood wool, the finest grade, is typically 0.005 inches thick and 1/32 inch wide, though it can be shaved even thinner.
The most common wood species are cottonwood, aspen, southern yellow pine, and basswood. Historically, cottonwood and aspen together account for about half of all production, southern yellow pine around 40 percent, and basswood about 8 percent. These species are favored because they shave cleanly without splintering and produce strands with good flexibility.
Packaging and Cushioning
Wood wool’s most visible use is as a protective packing material. The tangled, springy strands cradle fragile items like wine bottles, ceramics, and gourmet food products, absorbing impact during shipping. Unlike polystyrene peanuts or plastic bubble wrap, wood wool is fully biodegradable and gives packaged goods a natural, premium appearance, which is why it’s especially popular with specialty retailers and gift companies.
Its cushioning works through the same principle as a bird’s nest: thousands of interlocking strands distribute force across a wide area rather than concentrating it at a single point. Wood wool also wicks moisture away from products, which helps protect items sensitive to condensation during temperature changes in transit.
Insulation and Construction
When bonded with cement or other mineral binders, wood wool becomes a rigid board used for thermal and acoustic insulation in buildings. These wood wool cement boards have been used in European construction since the early 20th century. The combination works well because the wood fibers trap air (providing insulation) while the cement gives the panel structural strength and fire resistance.
Modern wood wool insulation boards have a thermal conductivity around 77 milliwatts per meter-kelvin, which places them in a similar range to other natural insulation options like cellulose or hemp. They’re not as thermally efficient as synthetic foam boards, but they offer better moisture management and breathability, letting water vapor pass through walls rather than trapping it inside. This makes them a common choice for older buildings where moisture movement through walls is important.
Some boards are treated with flame retardants to improve fire safety. Phosphorus-based treatments are the most common today because they don’t produce toxic or corrosive gases when exposed to heat. Older boron-based treatments, once popular for their low cost, have been phased out in the European Union over concerns about health risks from prolonged exposure.
Animal Bedding
Fine wood wool is widely used as bedding for small animals, from pet hamsters to laboratory rodents. It appeals to both pet owners and researchers because it produces very little dust. Commercially processed wood bedding typically contains less than 0.15 percent dust, compared to over 2 percent in unprocessed hardwood shavings. That difference matters for animals with sensitive respiratory systems.
Processing also dramatically reduces bacterial contamination. Commercially prepared hardwood bedding contains fewer than 140 colony-forming units of coliform bacteria per gram, while unprocessed hardwood shavings can harbor more than 10,000. For laboratory settings where controlled conditions are essential, this makes commercial wood wool a far more reliable choice than raw wood products.
Horticultural Uses
Gardeners and growers use wood wool as mulch, as a liner for hanging baskets, and as a growing medium component. Spread around plants, it helps retain soil moisture by reducing surface evaporation, while its loose structure allows rainwater to penetrate easily rather than running off. As it breaks down, it adds organic matter to the soil.
One consideration when using wood wool in the garden: fresh wood shavings temporarily draw nitrogen from the soil as microbes work to decompose them. This effect is mostly limited to the top layer of soil where the mulch meets the ground, so it rarely causes problems if you avoid mixing the wood wool deeply into planting beds. Composting it for a few months before use eliminates the issue entirely.
How Long It Takes to Break Down
Wood wool decomposes relatively quickly compared to other packaging materials. In moist, warm soil conditions, thin wood strands can break down substantially within a single growing season. Thicker strands or those bonded with cement will take considerably longer. The untreated variety is fully compostable in a standard home compost pile, where it also helps maintain airflow through the heap, preventing the anaerobic conditions that cause compost to smell.
Because it’s made from a renewable resource and biodegrades without leaving microplastics or chemical residues, wood wool has seen a resurgence as businesses look for alternatives to synthetic packaging. Many producers now source their timber from sustainably managed forests certified under programs like FSC or PEFC, adding another layer of environmental credibility to the product.