You may not ever think about yarn fiber processing, or it may be something you pay attention to, but it is quite important to what your yarn will and won’t do. I am by no means an expert, and like all things, yarn fiber processing has pros and cons for every step, and you should choose what matters to you. Whatever choices you make, you can use a small amount of knowledge to make the best choices.
I’m going to focus on natural fibers, because the die is cast for manufactured fibers at the time they are manufactured into fiber. The inputs are important though and can have a lot of impact on whether something feels like plastic or like a more natural fiber. Remember that yarn fiber processing is going to impact care and durability.
Yarn Fiber Processing of Manufactured Fibers
This relates to the inputs because there isn’t a lot of processing after the fiber is made. Are the inputs petroleum, chemical, cellulose or plant based? That is what creates the fiber compound. Beyond that, the surface textures imposed on the chemical solution will also cause manufactured fibers to behave differently. Any surface treatments (non-wrinkle, stain resist, etc.) will further impact that fiber. The resulting filament will then be processed into shorter fibers (either filament or staple) which can be spun and made into yarn.
Lest we forget, where the fiber is made is also important because there are environmental restrictions, or lack of them, that can cause the entire process to have long-term impacts. Environmental restrictions can impact the market price of fiber in addition to having a price in terms of positive or negative environmental impacts at the point of processing.
Yarn Fiber Processing of Natural Fibers
There are environmental impacts for yarn fiber processing of natural fibers too. Bleaching, washing, mercerizing, super washing, dyeing are all things done to fibers after they are harvested from plant or animal. Some are specific to the fiber (bleaching and mercerizing are limited to cotton, super washing to wool), and all have variations which have different impacts on both the fiber and the environment.
Washing can be a gentle process or one that has higher impact. What is done with the water used in the washing process? What is done with the waste? Brown Sheep Company has a great story about their washing process updates to their mill, as does Mountain Meadow Wool. These two companies have different methods, but the same goal: respecting the low-water environments they are located in, and using US wools.
Super washing, bleaching, mercerizing, and most dyeing are chemical processes. Even though they are being done to natural fibers, they have an impact on the fibers and potentially, the environment. You have probably noticed the great colors found in a lot of super wash yarns; this is related to the change to the fiber surface during super washing. Mercerizing similarly makes fibers take dye differently, and also smooths the fibers and makes them color fast. Super washing and mercerizing make a huge difference in how the fiber can be cared for. Natural dyes may not create the vibrant colors that can be obtained from chemicals, but may have high impacts in terms of water and energy consumption.
I think most companies are doing the job of yarn fiber processing that results in a desired price point. The gentler the processing, the higher the cost to consumers. Hand dyed yarn is more expensive because it is a hand process and cannot be done in the same quantities and using the same methods as vat dying large quantities of yarn.
Combing and Carding of Fibers
Carding is the first step to sorting the fibers for spinning. It can be mechanical or done by hand. There are lots of steps after the carding process, and these will often determine what type of yarn is spun from the resulting roving, sliver, or batts. Here’s a great graphic of the process for cotton. Combing comes after carding, but isn’t always done. You may notice on some labels it will say “combed cotton”, and denotes a greater level of processing, and usually a higher price.
Before the Yarn Fiber Processing
There is so much to each of these yarn fiber processes, and you can begin at the very beginning by finding out the origin of your fiber—was it raised naturally, treated with pesticides, allowed to roam free, or were the sheep or other animals penned. Some animals wear coats to protect their fleece or coats, while others pick up vegetable matter that might make it all the way into your yarn (I love that!). Was the crop treated with pesticides? What were the animals fed?
You can always ask questions, and read labels. Go to web sites for your favorite yarns and find out what they share about their yarn fiber processing. If they don’t share what you want to know, ask. I find that the more I know, the better able I am to match my yarn to projects and have happy results. Every step in the process causes changes–even if it is as small as getting rid of dirt, seeds, and unwanted vegetation.