What Does Crimped Wool Mean?

June 14, 2019

Not all wool is created equal. There are many types of wool, depending on the animal that it was gathered from, such as Lambswool, Merino Wool, Alpaca Wool, Cashmere, Angora. The best wool for use in a mattress comes from sheep. The amount of crimp in wool varies on the breed of sheep. There are hundreds of unique sheep varieties all with different and distinct hair. The hair or wool on a sheep can be naturally crimped or crimped by machine. In New Zealand, most of the sheep have long straight wool, with little to no crimp and therefore machines are used to crimp the wool. The best wool mattresses are made of many pounds of felted naturally crimped wool, not machined crimped wool. The crimp of the wool works like a spring, allowing the mattress to feel light and springy.

There is not enough organic wool produced in the United States to support the growing organic demand. The best natural and crimped wool we have found comes from Uruguay, which goes back over one hundred years. Uruguay has the perfect combination of sun, temperature and rainfall for farmers to care for the over 10 million sheep free grazing in an non-stressful open air environment. Without extreme weather, no mountains, deserts, or snow the sheep can live in a healthy outdoor lifestyle, herded naturally by gauchos sharing the land with the herds.

The best wool for mattresses has a high crimp and is not too thin or too thick. The Corriedale breed of sheep is the majority in Uruguay and is grown for it’s wool production, not for meat. The wool this sheep produces averages 25-30 microns thick, compared to that of Australia which measures less than 22 microns and New Zealand Wool that is over 34 microns. The Australian breed is not only thin, but is not naturally crimped. New Zealand wool is ideal for carpets due to its thickness.

Wool Structure

Image Source: Textinfo

Each wool strand has slightly different chemical composition, depending on the sheep variety. In finer fibers, these cells are arranged in 2 distinct halves. In coarser fibers, the arrangement is less distinct. These are the cells that create the crimp in wool. The 2 types of cell expand differently when they absorb moisture, which causes the fibers to bend. When the cells are arranged in 2 distinct halves, there is more crimp. The more random these 2 types of cells are arranged, the coarser the fiber because it creates less crimp. Crimp relates directly to fiber diameter. The crimp in wool fibers makes it soft and springy to touch. Crimp will also add bulk and trap a large volume of air between the fibers, which give wool good insulation properties. Finer wool with more crimp creates fabrics that drape better than coarser wool fibers with less crimp.

Wool has many benefits in mattresses. For one, it can be bent back on itself more than 20,000 times without breaking, compared to about 3,000 times for cotton, 2,000 times for silk therefore it is resistant to tearing and helps add years of life to your mattress. The outside of wool is a protective layer of scales called Cuticle Cells. They overlap each other like tiles on a roof. The exposed edges of the cells face away from the root end so there's more friction when you rub the fibre in one direction than the other. This helps wool expel dirt, be water resistant and gives wool the ability to felt.

Wool felts when fibers are aligned in opposite directions and they become entangled. The scales have a waxy coating which stop water from penetrating the fiber, but allows for absorption of water vapor. This makes wool water-repellant and resistant to water-based stains. The interior of the wool fiber is called the Cortex and make up about 90% of the fiber. It is made up of long tapering cells that overlap and are surrounded by the cell membrane complex. There are 2 main types of cells in the cortex