chines require a left twist for the upper or needle thread, when either a left or right twist may be used for the bobbin or looper. Multiple-needle machines often employ a right-twisted thread for one needle or set of needles and a left-twisted thread for another. This requirement necessitates the production of threads of both twists. The bulk demand is for the left twist, which is the standard in the sewing-thread industry, and unless otherwise specified by a consumer this is the twist supplied.

In cabled threads, such as 6-cord household thread, there are three twists, the first imparted in the spinning of the single yarn, the second in the ply, and the third in the cabling. The two methods of inserting the doubling and cabling twists are as follows: (1) Single yarns may be doubled into the ply in the same direction as in spinning, that is, to the right; this is designated "twist on twist." The finishing twist which cables the plied yarns is then inserted directly opposite the two preceding twists, making it regular-regular-reverse, or hawser twist. (2) A 6-cord thread may be made by altering the twist with each doubling, making the twist regular-reverse-regular, or cable twist. This twist is not successfully used for sewing thread, but is employed for the 6-cord crochet cotton known as cordichet or crochet twist. Six-cord sewing thread is made "hawser twist," though ordinarily it is referred to under the broader term "cable twist."

The amount of twist to be inserted in the spinning and in the doubling of the yarns is a technical detail of considerable importance in the production of high-grade thread. The twists must be properly balanced in order to prevent the thread kinking at the eye of the needle. The turns of twist per inch to be inserted in spinning are based on the square root of the yarn number, and the turns of twist to be inserted in doubling are based on the square root of the equivalent yarn number (obtained by dividing the single-yarn number by the ply) times a twist constant. The selection of the correct twist constant is a matter of judgment and involves consideration of various factors such as the length of staple of the raw cotton, the structure of the thread, and the use for which it is intended. In the case of straight-laid sewing thread for general consumption the ply-twist constant is usually about 52. Using this twist constant, a 3-cord thread made of 30s singles, for instance, would have 51⁄2 times 3.16 (the square root of 10, i. e., 30 divided by 3), or 17.38 turns twist per inch. The ply twist in ordinary 3-cord sewing threads ranges from about 16 to 30 turns per inch.

Finishes.-Threads, other than the natural grey, are made in three standard finishes: (1) soft or dull; (2) "silk," also called polished, hard, or glacé; and (3) mercerized. Between each of these classes are numerous intermediate finishes.

A soft-finished thread is one that has been treated with a sufficient amount of softening ingredients to give it slipping qualities and to overcome the harshness consequent upon the removal of the natural oils from the cotton in the bleaching and dyeing process. To obtain a silk-finished thread, a special dressing consisting of a combination of ingredients such as beeswax, gum arabic, paraffin, starch, and white soap, is applied to lay the fuzzy projecting fibers into the body of the thread. The polishing process works the ingredients into the thread and gives luster and smoothness. Formulas for sizing com

position for both soft and silk-finished threads are trade secrets, and are usually the fruit of much research and careful testing of thread behavior on different kinds of sewing machines and various types of work. There are no fixed standards of finish, and no two manufacturers' results are exactly the same. Finishing is a process that requires perfect control at all points, as varying treatment or even slight differences produce unsatisfactory results. The finish applied is directly correlated with the thickness and natural elasticity of the thread and the amount of luster desired. The results obtained are dependent not only on the ingredients of the sizing solution, but on mechanical adjustments in brushing and drying and upon tension in the winding operation.

The finish of the thread is the most important factor in the adaptability of thread to various usages and machines. Different finishes are required for different types of work. Silk-finished thread, which possesses the greatest tensile strength and smoothness, is the one generally employed in the leather industry to prevent friction and wear in the passage of the thread through the resistant hides. In the stitching of heavy, tightly woven textiles, such as canvasses, coutils, and denims, or of several superimposed layers of cloth, as well as in the manufacture of straw hats and vegetable fiber products treated with gluelike substances, it is also necessary to use silkfinished thread with easy slipping qualities. Basting thread is another article of this type of finish. Silk-finished thread is, moreover, often employed for general stitching in the needle of sewing machines in combination with a soft-finished under thread in the bobbin or looper. The needle thread has a more complex function than the under thread, and being subjected to a more severe strain it must possess greater frictional resistance, which is enhanced by the polishing process.

For general sewing and for stitching and seaming soft or sheer materials the soft-finished thread is the article of greatest consumption, both as an upper and under thread in sewing machines. The special advantages of soft-finished thread are its pliability and the ease with which it becomes set in the material, thus making the stitching inconspicuous and minimizing friction on the seam.

Mercerization, the third standard finish, is the application of a high silklike luster to the thread by means of immersion under tension in a strong solution of caustic soda. Mercerized threads are used for general stitching on all grades of work where a cotton substitute for silk thread is desired. In addition, its smooth, elastic qualities make it especially adapted to working buttonholes and to regular stitching on shoes and fine clothing.

Sizes.-The sizes under which ordinary cotton thread are sold in the market are known as ticket numbers and run as follows: 8, 10, 12, 16, 20, 24, 30, 36, 40, and from this number rising by increments of 10 to 200. Two-cord thread is generally produced in sizes ranging from 36 to 180, 3-cord thread from 12 to 130, 4-cord from 12 to 90, and 6-cord from 8 to 150.

Basis of numbering system. The ticket numbers of thread were originally based on the number of the yarn from which the thread was made. Cotton yarn numbering is inversely proportional to the weight of a unit length. It is expressed as the number of 840yard hanks to the pound (7,000 grains). A single yarn of such a

size that a hank of 840 yards weighs 1 pound, or a unit-testing section of 120 yards (one-seventh of a hank) weighs 1,000 grains, is designated as No. 1. If 120 yards weigh 500 grains, or two hanks consisting of 1,680 yards weigh a pound, the yarn is No. 2, or one-half the size of No. 1. Thus a unit of 120 yards of single yarn weighing 25 grains would be one-fortieth of the size of a No. 1 yarn and would be called No. 40 yarn. A pound of No. 40 yarn would contain 40 hanks and would therefore run 33,600 yards to the pound (forty times 840). The number or count of any cotton yarn is obtained by weighing a testing skein of 120 yards, called a lea, and dividing the weight in grains into 1,000. For a ply yarn the resultant is multiplied by the number of ends to find the count of the component yarns. The number of yards per pound is determined by multiplying the yarn count by 840 and dividing by the ply.

In the early history of the thread industry 3-cord thread was the first commercial product, and manufacturers numbered it according to the size of the yarn from which it was made. Thus a 3-cord No. 30 thread was made from three strands of 30s single yarn twisted. into one. In actual proportions the 30 3-cord thread was equivalent to a single strand of No. 10 yarn, as it would run the same number of yards to the pound. With the introduction and development of other cords or plies of sewing threads, such as 2, 4, and 6 cord thread, the system of numbering was not changed and the 3-cord thread became the standard for all. In order, however, to make the threads of the same ticket number, but of different plies, equivalent in diameter or circumference to the 3-cord, to permit their passage through needles with the same-sized eye, it became the practice to vary the size of the yarn from which the thread was made. As a result, the number of yards to the pound of thread of the same ticket but of different plies remains constant under this system. A 3-cord No. 30 thread, therefore, being made from 30/3 yarn measures 8,400 yards to the pound, and is equivalent to a 10s single yarn. To obtain this same amount of yardage in a 2-cord size 30 thread, two plies of 20s yarn would be employed; in a 4-cord size 30 thread, four plies of 40s; and in a 6-cord thread of the same ticket number six strands of 60s. In this instance the 2-cord, 3-cord, 4-cord, and 6-cord are all labeled with the same ticket No. 30 and are composed of different sizes of yarns, ranging from 20s to 60s, according to the number of ends in the thread. Since all of them measure 8,400 yards to the pound, they all fit the eye of the needle adapted to size 30 3-cord thread.

In ordinary 3-cord sewing thread, from No. 16 to No. 40, the labeled ticket number coincides with the yarn number from which the thread is made. Above size 40 there is a departure in the uniformity of the system, and the numbering is an arbitrary process. Size 50 3-cord thread is made nominally from 45s yarn instead of 50s yarn, size 60 thread from 50s yarn, size 70 thread from 60s yarn, and so on up to 110 ticket size. Above size 50, therefore, and up to size 110, there is a differential of 10 between the ticket size and the yarn number.

Six-cord thread between ticket sizes 16 and 50 is made from yarns twice as fine as the 3-cord bearing the same number. Above size 50 the differential of 10 enters into the numbering of 6-cord as well as 3-cord threads. While a 3-cord thread bearing ticket size 60 would

be made nominally from 50s yarn, the yarn used for a 6-cord thread size 60 would not be exactly double the ticket size, but would be 110s instead of 120s.

Although the system as outlined above is the basis of the nominal standards for the yarn sizes entering into the ticket numbers of thread, individual manufacturers do not strictly adhere to it in practice. The yarn from which the thread is made usually varies several counts below the theoretical standard. This divergence and lack of conformity may be attributed to the difficulty of adhering to the nominal basis because of variations in the constituency of the yarn in the technical processes of manufacture into thread. As the sizes of yarn are based upon the grey, subsequent treatment such as boiling off, bleaching, dyeing, twisting, gassing, and mercerizing not only affect the properties of the yarn but alter the yarn count. To make up for the gains or losses resulting from these various processes, the manufacturers start with a coarser grey yarn than called for, since the grist will come up to that required for the thread in the final product. Because of this permissible deviation from the theoretical standard in the yarn sizes which comprise the ticket numbers for the various plies or grades of thread, the following table is presented to show the average used among various manufacturers of thread in the United States.

TABLE 1.—Nominal standard and average count of yarn used by representative manufacturers in the United States for principal cotton threads in standard

sizes

That yarn numbers do not measure up to the theoretical standard is not, therefore, an indication of misrepresentation. It is the necessary result of the technicalities of the industry and the attempt to make the threads of different plies but the same ticket number correspond to the same diameter, in order to permit their passage through the same needle with approximately the same tension.

Numbering of mercerized thread.-Mercerized cotton threads for manufacturers' use in both 2-ply and 3-ply are numbered according to the standard used in numbering silk thread. In this system the variable lengths of silk per ounce are designated arbitrarily by alphabetical letters, ciphers, or series of ciphers, as shown in the following table:

TABLE 2.-Typical system of numbering mercerized cotton thread ("ounce goods")

The nominal yarn counts used by different manufacturers vary, but the insertions in the table above are representative of trade usage. Numbering of cotton-welt thread.--The sizes of heavy cotton threads used for sewing welts on shoes follow the system employed in the numbering of heavy linen welt threads. The ordinary size of the single bleached linen welt yarn is 1911⁄2 lea or 20 lea, and the ticket numbers are based on the number of cords in the thread. A No. 6 linen-welt thread consists of six cords or plies, each being composed of size 1911⁄2 lea. The present practice of the cotton-thread manufacturers is to match the diameter of the cotton-welt thread to the linen. In straight-laid thread this is done by using a size 84 singles cotton yarn which corresponds approximately to the 1912 lea linen singles. The number of cords in plain-laid cotton-welt thread ranges from 3 to 14, and the various threads are ordered according to the cord. In braided welt thread, on the other hand, the number of cords or ends braided together is constant for all ticket numbers, 16 ends being the general usage. The yarn count of the individual ends, however, is varied to obtain different sizes of the finished welt thread. The ticket numbers applied to the cotton-welt thread correspond to those used for linen thread having the same diameter. A braided cotton-welt thread of ticket size No. 7 is, for instance, made up of cotton yarn of such a size that 16 singles equal in diameter seven strands or cords of linen yarn of size 191⁄2 lea.

Colors.-Manufacturers of cotton thread and art neeedlework cottons follow the colors determined upon by the Textile Color Card Association and are therefore constantly shifting their color range from one season to another. Domestic sewing thread and handwork cottons are made in more than 200 colors, but each manufacturer, however, has a standard assortment of approximately 80 or 90 staple shades. The bulk of the colors are produced in sizes 50, 60, 70, and 80. The color card for manufacturers' threads is somewhat smaller than that for the domestic line, embracing 185 shades in the complete range. About 50 of these are standard shades in steady demand. A fairly large quantity of thread for industrial use is sold in the natural unbleached grey as a bobbin and looper thread in the manufacture of workingmen's garments and for serging operations. Put-up and yardage.-Prior to the war the standard form of put-up for domestic cotton thread was the 200-yard length wound on small wooden spools. During the war period the quantity per spool was

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