The word sounds almost frightening, we know… However, we often read it on our clothes: “pure, mercerized cotton”. What does it mean exactly?
And why keen stitchers should also be interested in it? The reason is very simple: because mercerization is a process giving the natural fibers composed by cellulose, such as those of cotton and flax, increased shine, hydroscopic capability (i.e. the ability to absorb humidity and disperse it, in short), as well as more dye affinity, that means the capability of a fabric of getting a certain color. On the whole, mercerization ensures better resistance to the final fabric.
Developed in the mid 1800s by the English chemist John Mercer (hence the name “mercerization”), who tried to process cotton fibers with caustic soda, to tighten it and thus making it easier to dye, mercerization was then improved, by keeping the fabric under tension during the procedure, just to avoid its tightening.
Today, the process is the result of several further improvements and takes place with a quick bath in caustic soda, at moderate temperatures, followed by a second bath neutralizing the exceeding caustic soda. As a matter of fact, mercerization makes natural fibers “plumpier”, turning them from flat to circular and, therefore, increasing the surface of their cells. This turns into a more pleasant texture of the fabric itself, as well as into a better capability of absorbing dyes, as already mentioned (and this means also that smaller quantities of dyes are necessary to let the fabric have a very good end color shade), and improved tear-resistance.
This is why cross-stitch and embroidery linen, too, is often mercerized.
The “side effect” of mercerization can be a certain feeling of “stiffness” ( our grannies already used to refer to mercerization as “stiffener”): but it usually disappears after the very first washing. In the instance of precious embroidery cotton and linen, please, remember they call for delicate washing.