This section is from the book "A Manual Of Home-Making", by Martha Van Rensselaer. Also available from Amazon: A Manual of Home-Making.
Darning is the repairing of cloth by the weaving in of threads to replace torn or worn warp and woof threads. Knitted fabrics, also, are mended in this way. Darning is a less conspicuous method of repairing than patching, although on garments which are subjected to very hard wear or to much laundering, it is not so satisfactory. In woolen garments darning is usually preferable to patching, since it is less bulky and woolen clothes are not so often laundered. .
* Ext. Circ. 14, Coll. of Agr., Univ. of III.
To make the darn as inconspicuous as possible, a raveling of the material is used, or if this is not strong enough, a silk thread is split into thirds, and one of these strands is used. When only-one set of threads has been severed, whether it be warp or woof, this set alone needs to be supplied. If both warp and woof are broken, they must both be woven in. The stitch which is used is a short, loose running stitch, and, as far as possible, the darning is done on the wrong side. The edges of the tear must be neatly joined together by passing over and under them in the alternate rows of sewing. The distance which the stitches are carried outside the tear depends on the strength of the surrounding material. If it is very much worn, the darning must be made to cover the thin places. To form a guide for the darning stitches, a basting thread should be run just outside the area to be darned.
The three forms of tears which most often occur are straight, diagonal, and three-cornered, or hedge. Sometimes there is a hole which is too large for ordinary darning, and it can be repaired best by placing a patch underneath and darning the edges down over it. The method of repairing these tears follows:
The tear may be across either warp or woof threads, so the missing ones should be woven in. Start the running stitches as far above the cut, and carry them as far beyond, as it is necessary, in order to reinforce the worn part. When the tear is reached, pass over and under the two edges in alternating rows, so that they are firmly held together. Be very careful not to draw the threads too tightly as this will cause a puckered appearance.
In a bias or diagonal tear both the warp and woof threads are severed, and so they must be supplied. The running stitches should follow the warp and woof threads of the cloth, not placed at right angles to the cut. The warp threads should be put in first as far beyond the tear as necessary, and the woof threads then woven in. The woof threads may be laid farther apart than the warp. As this tear is on the bias, care must be used not to stretch it.
In the three-cornered tear, also, both the warp and the woof threads are severed, but not often on the bias. The darning is first done following the warp threads from one end to the corner, then the woof threads are replaced in the same manner. At the corner, there will be a square darn where the supplied warp and woof threads should be interlaced.
Cut a piece of the cloth large enough to cover the hole or worn place, and to extend far enough beyond to reinforce it. If the material is figured or has a nap, it should be matched. Baste the right side of this patch to the wrong side of the garment with the warp and the woof threads matching. On the right side darn over the raw edges, without turning them under. If the ragged edges are not entirely trimmed away, the unevenness of the edges will make the darned place less conspicuous. Do not carry the running stitches across the patch if it is a large one. The edges of the patch on the wrong side may be sewed down with long hemming stitches.