On the occasion of the 10th anniversary of "Good Eats" I've decide to get my "nerd on" and offer a detailed explanation for a small detail.
From time to time I read discussions on couches and couche care on these pages and I encounter what I will call "folklore" about the fibers and fabric care.
I will not wade too deeply into the various controversies, but I do have some small expertise on fibers and fabric care and would really like to share it for those who desire a more complete understanding of this fascinating topic.
Let's start with linen. Linen is a bast fiber (other common bast fibers are jute, hemp, and ramie) which means that it comes from the center stalk of a plant. In the case of linen, it comes from the center stalk of the flax plant. The fibers that are known as flax before they are spun and linen after they are spun are the long fibrous strands found between the outer "bark" and inner core of the flax plant. Although the flax plant obligingly provides us with seeds for use in our baking as well as fiber, the culture is different between those plants destined mostly for fiber and those destined mostly for seed. Plants to be grown for fiber are planted close together so that the plant will grow tall and straight with little branching and fewer flowers. Plants grown for seed are planted further apart so that they will branch and produce more flowers. Additionally, different varieties of flax are cultivated commercially for these purposes and to achieve these ends, so while it is a romantic notion to think that the very same plant gives us linen for our couche and seeds for our bread, it is a just a bit invalid here in the early days of the 21st century.
Because it is a bast fiber, linen is extremely strong. Also bast fibers do not have any crimp (like a lock of wool or a cotton fiber) and so will not shrink.
Because of the expense of producing cotton (more later) and its limited growing range, linen was the most commonly used fiber in Europe until the end of the 18th century and continued to be widely used until the invention of the cotton gin.
Flax becomes linen in a multi step process. After the plant has reached maturity, it is harvested - preferably by pulling it from the ground root and all to maximize the length of the fiber. It is dried, the seed pods removed, and then retted. Retting is a process where the flax is kept wet - either by submerging it in water or keeping it on a moist surface (like the dew on grass) until the outer layer partially decomposes exposing the fibers. Once again it is dried. The next step is breaking where the outer layer is further broken mechanically. Scutching comes next - where a knife like device is used to further scrape the outer layer from the fibers. At this point the fibers are mostly clean, but they are further cleaned and straightened by a process known as hackling. A flax hackle looks something like a medieval torture device and is a board from which protrude number of sharp iron spikes. The hackling process will produce long fibers that will be spun into fine linen and short yellow fibers called "tow." When we look at a blonde child and call her a "tow head" we are comparing the color and texture of her hair to the color and texture of the tow produced by this process. Tow can also be spun, but it will not be as smooth as fine linen. After all this, the fibers are spun (after mounting them on a distaff) (oh, and they are usually spun wet to give the smoothest results) and become linen. This can either be bleached (by the action of chemicals or the sun) or left natural. Then it is woven and there is one more chance to bleach it.
After all it has gone through to become cloth; one really must ponder why we have come to think of this fiber as "delicate." Yes, it can be finely spun to produce a very fine fabric, but this is a tough fiber indeed.
I have planted and tended flax, processed it and spun it into linen. This is one of the reasons why $9 per yard for couche linen does not cause me to flinch. While I understand that people's economic situations and propensity to spend vary, I consider the number of steps to create that cloth and I can't begrudge anyone the money.
One characteristic of linen is that it absorbs and evaporates moisture quickly. This makes it particularly suited for use as a couche, since in theory one of the functions of the couche is to pull moisture from the surface of the bread to prepare it for better scoring. This also means that once a linen couche is used and has absorbed some moisture, it will dry more quickly and so prevent mold.
New linen couche cloth needs to be washed to rid it of any chemicals used in finishing. It will ravel somewhat, but well woven linen couche cloth will not ravel excessively. It can be washed in hot water simply to get it as clean as possible. There is no need to use hot water to shrink it (for, as mentioned before, it can not shrink). Mild soap should be used for fine or antique linens, but for a couche as long as you feel good about it rinsing out of the cloth, the linen does just fine with any modern detergent (I routinely launder my linen aprons in regular detergent and they are holding up just fine...). This being the one of the sturdiest fibers there is (consider that sails were made of linen) there is no need for a gentle cycle for couche cloth. (Again, fine or antique linens are another diverting topic in and of themselves and are treated differently.) Linen couche cloth can safely be dried in an automatic dryer. (Actually, the dryer is the biggest enemy of linen (and cotton) - not because of the heat, but because the tumbling action will cause friction on the fabric and pull off parts of the fiber which we experience as dryer lint. However, since the couche will not be washed often - have no fear.) Fabric softeners (liquids or dryer sheets) should not be used as they impact the absorption qualities of the fiber (this also goes for cotton.) (Won't get involved in the whole "toxic chemicals" debate.) It might be slightly puckered after washing and drying (and again, this is wrinkling, not shrinkage) but since this is the one and only time you should be washing it, any raveled threads can be trimmed and the cloth is ready. No need to hem or serge it. If you wish to iron it, it should be ironed when quite damp.
Linen contains a wax that when exposed to the heat of an iron will provide the fabric with a luster. We hardly care about this in our couches, but when dealing with fine linen cloth it is best to iron it on both sides to maximize the luster.
Cotton requires a warm climate and a long growing season to reach maturity. When picked from the plant, the cotton contains about 2/3 seeds to 1/3 fiber. Prior to the invention of the cotton gin, these seeds needed to be picked out by hand or by putting each cotton tuft through a couple of rollers to squeeze out the seeds (either one a labor intensive process.) When the cotton is dried after harvest, the fiber dries into a flat ribbon shape that corkscrews. This is the crimp that will cause cotton to shrink. It also gives cotton more elasticity than linen, so it is less prone to wrinkles.
Because cotton fibers are relatively short (different varieties of cotton have different fiber lengths, but they are all considered short in relation to wool - and of course linen where the fibers may be 2-3 feet in length), they require a great deal of twist when spinning. Although cotton is easy to spin, putting in a lot of twist causes spinning to be relatively slow. In an environment of hand spinning or limited mechanical spinning, cotton is a luxury fiber. Most folks who live in the US are familiar with the role that the cotton gin played in the American South and how ensuing events lead to conflict.
I have also planted, grown, harvested, cleaned, and spun my own cotton. It seems like it should be less effort than processing flax, but harvesting is kind of grueling (yes, the cotton pods are sharp!), and picking out the seeds - although simple - is pretty time consuming. Also, I could grow flax in Colorado and not cotton. And I like it here... In fact, it is this limited growing range that created an important cotton trade. Flax, on the other hand, was readily grown in many climates and never reached this kind of economic importance.
Cotton does not have the wicking power of linen so will take longer to dry and "in theory" will not perform as well as linen to pull moisture from dough. I won't weigh in on the cotton vs. linen couche decision except to say that I like the feel of linen as opposed to cotton. I like touching it and I try to use it when I can. (A linen bath towel dries like nothing else, by the way.) Obsessive perfectionists might want to blow the money to get the absolute perfect fabric for the application (and it is.) If we look backwards to "the old ways" - especially old European ways - linen would be the fabric of choice as cotton would have been too rare and expensive. But cotton is just fine.
Once again, a well woven cotton couche will ravel when washed (and it should be washed to remove finishing chemicals), but not so much as to be a problem. Since this should be the one and only time the couche is washed, these threads can be trimmed and will not be a problem again. No need to hem, serge, etc. unless even the smallest amount of raveling (in the past) is something you simply cannot tolerate. Similarly, since the couche will not be washed again, washing it in hot water will cause it to shrink a bit, but there is really no need to shrink it. Most cotton that is commercially available has already gone through enough processing so that any major shrinkage has already occurred.
No matter what fabric you use, the couche should be dry before storage, or stored in such a way that it will dry quickly in storage. Those of us in dry climates can be a bit careless, while those in humid climates might wish to find a spot to hang couches until they are dry. Folding any fabric will result - over time - in permanent creases and will eventually cause weak spots in the fabric along those crease lines. "Over time" is sort of a relative thing. For a couche which we might be using for ten or twenty years and will not be passed down to the children and grandchildren, this should not be a concern. Creases will develop, but they will not substantially reduce the functionality of the couche. For treasured quilts or tablecloths, many experts recommend that they be rolled, or if that is not practical that folds be padded with acid free tissue paper and that periodically they be re folded in a different way. Personally I can roll my couche and so I do.
Yes, it's a long winded post with no pictures and I realize that it will fade away as more blogs are created, but I've really done my homework on this and attempted to present facts as opposed to folklore. Hope it is useful and dispels some myths.