Bar tacking is a specialized sewing stitch designed to provide great tensile strength to the garment or equipment it is used on. It is commonly used on backpacks, tents, tactical gear, and other heavy wear sewn items where normally sewn stitches might give way at a crucial moment. In general, the tacking is a sign of good quality, although the rest of the product should always be looked over carefully as well. When a sewing pattern calls for bar tacking, it indicates that the designer feels that section of the pattern is a critical area that needs extra reinforcement.
To create bar tacking, a manufacturer sews a very tight zigzag stitch across the width of the material. In some cases, the sewer may go over the seam again, causing the stitch to have an x-like form. Usually, very strong threads are used so that they will stand up to high pressure. When done correctly, bar tacking can help support loads of up to 400 pounds (almost 200 kilograms). Many backpacking companies in particular pride themselves on the number of bar tacks integrated into their products, claiming that they will wear harder and longer than the competition.
For commercial work, specialized sewing machines are capable of handling high volumes of bar tacking through heavy materials like nylon webbing and canvas. Commercial machines tend to be expensive, however, and smaller companies prefer to modify their existing sewing equipment. Home sewers can create this stitch if they have a zigzag setting on their sewing machines, although they may have to do it by hand if the material is very thick. In both cases, a heavy weight waxed thread should be used.
Bar tacking works to reinforce material by spreading pressure more evenly along the width of the fabric, with a large number of stitches covering a small area. When pressure is put on the tacked area, the thread will not give way as readily, because it is not in a straight line in grain with the fabric, as most sewing is. Indeed, fabric will more frequently give way around the stitching, especially if it is old or if it has been stressed by the elements.
Rock climbing harnesses, hang gliding gear, and a wide variety of other products manufactured for outdoor sports are reinforced by bar tacking. Because much of the gear is critical to survival, it is important for users to frequently inspect and test such gear and to discard equipment that seems unreliable. In general, if support gear is frayed or worn, stretched out of shape, or torn, it is probably not safe for use.
