About how felt is made

Felt mills

Wool felt is made in mills, which were traditionally found in rural areas, close to the wool producers, and near a source of water. The machine production of wool felt is a highly specialized process that requires expertise. Today, only a few felt mills that remain that follow the procedures, and often use the machinery, that were developed over a century ago.

Raw wool

After shearing, the wool is sorted by quality and color. The wool has different qualities depending on which body part of the sheep it comes from. Because sheep are free-roaming animals that graze in meadows, leaves and twigs get caught in the fleece. The fleece is cleaned with water to remove plant matter and dirt, as well as some of the sheep’s natural lanolin. Sometimes white fleece is carbonized to whiten the wool and remove even more dirt and plant matter.

Prepairing the fiber

At the beginning of the process, the wool fibers are fed through a willower to untangle the wool and remove remaining impurities, such as dirt and sand.It separates the fibers and starts to lay them all in the same direction.

Carding process

Carding involves combing and untangling the wool. Feeders allow specific fiber weights (thickness) to pass into a cylinder, forming a standardized fiber web. The fibers are carded (similar to combing or brushing) to align them, so that all fibers run in the same direction. The machine merges several layers of the resulting fluffy wool sheet (with fibers laid in alternating directions), resulting in what is called a batt. The batts are rolled neatly and are then ready for felting.

The actual felting process

This is where the actual felting occurs. Multiple batt layers of batts are laid out on a conveyor belt. The combined batt layers are subjected to heat and moisture simultaneously by passing through a steam table. The hot and wet wool batts are then passed on to a plate hardener that applies pressure and oscillates, thus matting the material.

The outer layers of wool fibers consists of overlapping scales similar to fish scales or the scales on human hair. By applying heat and moisture, the scales are encouraged to open up. The friction of the plate hardener causes the scales of different fibers to interlock, resulting in a thick, strong wool mat. At this stage, shrinkage occurs width-wise.

Fulling

At this stage the fibers have already bonded but extra density is required to result in the desired strong and durable felt material. The batts are fed through pairs of rollers covered with threaded rubber, similar to a tire. Pressure, heat, moisture, and movement are applied and cause the batts to shrink length-wise. The felt becomes denser and thicker, and the more it is manipulated, the tighter the fibers lock together. In this process, the wool felt may lose up to 50% of its elasticity. A 31 meter piece of felt may come out of the fulling machine 6 meters shorter.

Washing and scouring

To prepare the felt for dyeing, it is washed and sometimes scoured to eliminate any remaining dirt and impurities. Washing also results in uniform penetration of dyes so the felt is dyed evenly.

Felt dyeing

To create a single dye lot, felt pieces measuring 25 meters are sewn together. Dye lots vary depending on felt thickness and weight. As a rule of thumb, a dye lot measures 100 meters when the felt is 2mm thick, 75 meters when it is 3mm thick, and 50 meters for 5, 8, and 10mm felt. The felt is dyed with plant based textile dyes in dye vats, using heat to set the dye. This part of the process may take up to six hours. Colors are always compared to a control sample to ensure uniform, standardized colors.

The drying process

The wet, dyed felt is laid out on a drying bed prior to being dried with heat. At this point, it is almost ready for the last part of the process.

Shaving and edging

Because felt is not a woven material, loose fibers may stick out of the felted surface. Both sides of the felt are shaved to remove these fibers and ensure that the felt is smooth. Additionally, a gaging table may be used to neatly trim the edges for an even finish.

Pressing and ironing

At the end of the manufacturing process, felt is usually thicker in the middle and thinner at the outer edges. As a last step in the manufacturing process, the material is pressed and measured. This way, you can be sure it complies with the specified allowance for thickness.

Felt rolls

At the very end of the process, the felt is rolled into neat bales. It is now ready for delivery to buyers.