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Ask any Boy Scout and he'll tell you how many dozens and dozens of different ways there are to tie pieces of rope together or to other things. There are hundreds of books on how to tie knots and organizations dedicated to studying the art, science and beauty of them. There are even university scholars who study the theory of knots and write mathematical formulae to describe their structure.
When it comes to creating beautiful area rugs, there are also a wide variety of knots used. But before we examine a few of these, we need to understand a very important attribute of all area rugs. It is what is referred to as knot density.
Knot density is a fairly simple concept and calculation. You take one square inch of a finished rug and count the number of horizontal and vertical knots in each dimension. (The technical terms for these are warp and weft and are usually only visible on the underside of the rug.) In the metric system, obviously different units are used and the number calculated will be different. Both centimeters and decimeters are used to specify knot density.
You multiply the two numbers together to get the knot density. However, since the two numbers are usually the same in a handmade rug, you can just square the count of knots in a linear inch.
A high knot density doesn't necessarily mean that one rug is better than another. This is particularly true of antique rugs for which the value is based upon other factors. In addition, knot density isn't a clue as to the durability of a rug. Instead, knot density is directly related to how sophisticated the design on the rug can be. In order to make intricate curves and patterns, a high knot density is required. Interestingly, it's complete analgous to things such as photo resolution and print dpi (dots per inch).
With handmade rugs too, knot density is directly related to how long it takes to actually weave the rug. Since it takes a skilled rug-maker approximately 10 seconds to tie each knot, that translates to only six knots per minute. A 9' x 12' area rug at a rather modest 150 knot density is going to have a staggering 2,332,800 knots. Depending upon how many hours a day the weaver spends working on the rug, this can take over two years to create!
In case you're interested, here's the calculation:
- 9 feet x 12 feet = 108 square feet = 15,552 square inches
- 15,552 square inches x 150 knots/square inch = 2,332,800 knots
- 2,332,800 knots divided by 6 knots/minute = 388,000 minutes = 6480 hours
- 6480 hours divided by 8 hours per work day = 810 days = 2.2 years
Some area rugs have knot densities of up to 1000 knots per square inch. These are very rare, usually made of silk and incredibly expensive - not only because of the amazing craftsmanship, but because it probably took a team of weavers many years to make.
A little important terminology:
As mentioned previously, the terms warp and weft are used to describe the vertical and horizontal strands of fibers in an area rug. Warps are important because the knots are actually tied to them, while the wefts are passed through them. It's critical that the tension on the warp strands be kept consistent or the rug will wrinkle. If a rug has fringes, it is an extension of the warps that creates this.
Wefts are the horizontal strands and unlike warps, are added as the rug is being woven. They separate each row of knots and pass over and below the warp strands. Another term related to wefts is selvedge. This is each side of the rug where the wefts begin and end.
The material used for the warps and wefts is usually the same, but it is not necessarily the same as the yarn used to weave the rug. It's not uncommon to have cotton warps and wefts - collectively referred to as the foundation - in an otherwise all-wool rug. Then again, for consistency, many rug artisans prefer everything to be the same.
There are three types of knots primarily used in the creation of handmade area rugs today.
The Persian knot - sometimes also called the Senneh knot - falls into what is classified as an asymmetrical knot. It is common and popular in Iran, India, China, Turkey and Egypt. It is rather simple and easy to tie. The yarn is wrapped around one warp strand and than passed under the neighboring warp.
The Turkish knot, or Ghiorde knot as it is sometimes called, is a symmetrical knot favored in parts of Turkey, the Caucasus region and by Kurdish craftsmen. To form a Turkish knot, yarn is passed over two neighboring warps. Each end of the yarn is then wrapped behind one of the adjoining warps and brought back to the surface in the middle.
The Tibetan knot is not as common as the Persian or Turkish varieties because it is much more difficult and time-consuming to tie. However, it is very distinctive and gives rugs using it a unique look and texture not otherwise attainable. To tie it, a temporary rod is placed in front of the warp. The thickness of the rod can vary and establishes the length of the pile. A continuous piece of yarn is looped around two warps and then once around the rod. When a complete row of loops is tied, they are cut to complete construction of the knots.
An ancient knot called the Jufti knot was popularized in the Khorasan region of Iran. There are multiple varieties of it and it usually involves looping a singly yarn through four warps at a time. It is rarely used today.
Now it's time for you to show off a bit. Ask an area-rug salesperson what kind of knot was used to create that gorgeous rug you are considering buying. Start that quest by visiting Rugs Direct.