Rugs, Carpets and Carpeting - seam sealer

What exactly does seam sealer do? Is it to seal the backing so the nap will not come loose after cutting the carpet to seam?Also is it applied just to the edge of the backing after being cut?

Seam sealer should be used on all carpets. It is a clear, odorless adhesive that is applied along the edges of the carpet backing that are to be seamed. The purpose is to keep the carpet fibers from detaching from the backing along the cut edges. The use of seam sealer is particularly important if installing berber and level loop carpets. The seam sealer prevents seam raveling. Because applying seam sealer takes time, most installers will not use it unless the customer insists and is there to keep an eye on them. Unfortunately, most customers don't know about seam sealer. Once the carpet is installed, it is impossible for the customer to know if seam sealer was used or not unless the carpet starts to ravel.

A professional installation is important to the performance of the carpet over the long run. Carpet dealers typically subcontract the installations and guarantee the installation for one year. Because carpet installers get paid by the yard, the more yards they install the more money they get. So, they are typically in a hurry and take shortcuts so they can get to the next job. Skipping the power stretching and the seam sealing are the two most common installation requirements that are violated.