The knots themselves are tied on the warp strands. The knots surround two of the warp strands in one of two manners. Either the Persian (Senneh, asymmetrical) or Turkish (Ghiordes,symmetrical)knot is used. The difference is illustrated left

Unlike the previous illustration, however, most weavers depress the warp strands to some degree. That is, instead of both warp strands lying side by side as illustrated, the warps lie on top of each other. This will allow for a much more compact structure and greater durability in most cases. The degree of depression can also be important in terms of determining the provenance of any particular rug.

After one row of knots is tied completely across the warp strands, a weft strand is placed over and under alternating warp strands. The weft may be placed once, twice, as many as seven times after each row of knots. The weft, like the warp, may consist of wool, cotton or silk. The number of times the weft crosses after each row of knots can also be very helpful in identifying the origin of a rug.

After the weft is in place, certain areas will place a filler thread, which is normally heavier than the weft. This allows for less wool to be used and normally makes for coarser, poorer wearing rug. In some carpets and rugs the filler thread allows the "handle" of the rug to be more flexible - most notably in well pounded rugs of workshop production.

After the weft (and filler threads) are in place, the knots and weft are pounded into place. The degree to which the knots are pounded is a crucial determinant as to the durability of the rug. This is referred to as the "handle" of the rug. The heavier the handle, the greater the compactness of the weave and the greater the durability of the rug.

The handle of the rug is one of the most overlooked factors in rug literature. The Bidgar rugs are will known for their incredible heavy handle. A special device is used in Bidgar and the knots are extremely compactly pounded. It is one reason the rugs of Bidgar are so highly prized.

In most weaving areas, after several rows of knots have been tied and pounded into place, the excess pile is then sheared to its final height. In rugs that use a very intricate floral pattern this shearing is done much closer than in the bolder geometric design rugs. Normally the knot count is also much finer in the highly floral rugs.

The type of wool used is another important factor in determining the quality of a rug as well as being useful in determining provenance. Different regions will use characteristically long, silky wool (i.e. Kazaks), short staple, coarse wool (commercially produced Tabriz rugs), or wool that is generally lower in oil content (Meshad), or highly resilient wool (Keshans). Sometimes the type of wool used will also influence the final product. If the wool is thick and heavily plied a coarser rug will usually result (Heriz, Kazak).

The technical analysis of fibers used in rugs can be a good sign post in determining the origin of a particular rug. Technical analysis can be done on the warp, the weft, materials used, how they are spun, how the spun materials are plied, the type of knot used and whether or not the warp strands are depressed.

An example of technical analysis is:

Warp - Z2S wool in ivory, dark natural mixtures; depressed.
Weft - Z2S wool- natural mixtures; two shots
Pile - 2Z wool; Ghiordes knot, pile slanting left

This translates to:
The warp is made of Z spun wool, 2 threads of which are plied in an S direction.
The weft is the same with it passed twice after each row of knots.
Pile is wool made with two Z spun threads. The knot used in symmetrical on depressed warp strands. Pile slant to the left indicates that the left warp strand is the depressed one.

The ìZî and ìSî spin refers to the way the wool is spun. The Z spin means the fibers have been twisted counterclockwise (to the left) to run at the same angle as the stem of the ìZî. The ìSî spin is clockwise (to the right) and follows the axis of the ìSî. The individual strands are mostly Z spun then S plied. Always the strand is plied opposite of the spin.

Another important feature in technical analysis is the side and end finish that is used in a rug. One must be wary of repair work done in this aspect. Simple weft overcasting of sides is frequently done but in some areas a selvage process of finishing the sides can be helpful in determining provenance. As well as the process used, sometimes the material can be helpful also (i.e., cotton selvage in Shriavan area pieces).

Different types of warp finishing can also be a helpful identifier or origin - whether a kilm skirting, braiding, banding, weft float-broacading or simple knotting of warp strands as they emerge from the pile. Each color plate will not the important differences