To make clothing more waterproof, the product seams are often sealed, since these are punctures made by needle during product joining, through which the water may penetrate.
There are two ways to seal seams on a waterproof clothing.
Seam taping is applied to products, where parts made of waterproof materials are joined together by needle and threads. The tape heated by a jet of hot air melts and seals the holes present in the fabric from the needle.
Seam welding by means of ultrasound is applied to products, where it is necessary to join the parts without the use of a needle and thread. Part edges are adjusted and tightly pressed against each other and the support. Then it is pointed with a welding tool (tip) connected to ultrasonic transducer and the generator is switched on to start the transducer.
Under ultrasonic influence, the joining parts are heated up in the contact zone to the temperatures giving the materail high flexibility. At first there is a physical contact between the surfaces and molecule activation by bond opening, then— the chemical interaction of materials being joined. The result is flat elastic seam totally moisture-resisting.