Upholstery springs should be tied down using clove hitch knots or overhand knots to prevent springs from slipping out of position. Seat springs can be lowered to form a rounded or flat top, depending upon personal preferences. Springs need to be tied uniformly so that upward expansion is controlled precisely in the seat.
Coil springs can be tied down using jute twine and several knots on one spring. The knots tie each spring together along the twine. Many armchair manufacturers utilize a four-way tie system that features four strings and eight knots on each upholstery spring. Each string is tacked to the frame and then knotted on one side of the top of the spring and then tied to the opposite side before going on to the next spring in line. The pattern continues until each spring in the configuration has eight knots.
The four-way tie is used for extra support for round seats. Two-way ties use four knots on each spring for flat seats. Twine is measured by finding the distance across frame lengthwise and crosswise and then doubling the figure. Add an additional 24 inches of extra twine to allow for knots in each segment.
Newer furniture typically uses "S" springs that do not need to be tied.