One end is knotted approximately 18 in. from its free end to a tack driven into the edge of the frame next to the spring. A secondary reason for tying springs is to keep them compressed to about two thirds of their expanded height so that the spring action will be limited by, and fall entirely upon, the tying cord. Therefore the spring nearest the tacked end of the twine should be depressed to a height of about 7 in., with its outer rim compressed to 6 in. before it is fastened to the twine by means of a clove hitch (Figure 6.8). The long free end of the twine is then hitched or knotted across the top of the spring to the opposite side, then across to the middle spring, where it is tied with two hitches in such a manner that the tops of the springs are spaced the same distance apart as are their sewed bottoms. The end of the twine is looped around a tack driven into the frame on the opposite side of the frame from the first tack, and the twine tightened to compress the springs properly before the tack is driven home. A second tack can be added for extra security As indicated in Figure 6.9, the return ties consist of knots tohe outside edges that hold them down to a 6in. height. If more than 18 in. of twine has been allowed, the cord can be carried on over the tops of the springs, being knotted at each opportunity; the more the spaces in or around the springs can be filled UPHOLSTERY AND SEAT WEAVING with firm twine, the better will be the control of the springs and the support for the stuffing. Lateral ties are added in the same manner, as shown in Figure 6.9 followed by diagonal ties in both directions. The last twine crossing the spring centers should be knotted to all other twines to prevent wear. In addition, wherever twines cross each other, they should be knotted. Care must be exercised that successive tyings do not compress individual springs, or rows of springs, lower than others. Fig. 6.9. Fastening outside springs. Covering the springs. To cover the springs burlap is tacked to the wooden frame along folded edges. It is pulled just tight enough to prevent depressing the springs. To keep it in position it should be sewed to the springs with large stitches by means of a 6in. curved upholstery needle, each spring being looped in three places. Forming the hard edge. If tow is used as stuffing, about 5 lb. should be worked down so that it extends at least 3 in. over the edges of the seat frame. Whatever the type of stuffing used, it should be at least 1 in. thick and extend over the edges far enough to compress into a fairly hard roll of 3 to 4in. diameter. The stuffing is covered with a piece of light burlap large enough to be sliptacked onto the frame while it is being stitched through the stuffing to the lower burlap covermg. A straight needle is thrust up and down through both layers of burlap, making stitches about 3 in. long just outside the outer springs. After the four sides are sewed and the stitches are pulled tight, a few irregular stitches are taken in the center, to compact the seat.