Counting Knots the easy way - however there are a few snares that clients can fall into. There are an alternate sorts of knots yet the most mainstream are the symmetrical Turkish knot and the Persian knot
While the type of knotting can be important for appraising the origin of a rug it is vital when looking at knots per square inch (KPSI).
Counting the KPSI you simply measure the knots across a vertical and horizontal inch and multiply the two. Most rugs fall between 100 and 200 KPSI. Some rugs such as Heriz, tribal rugs and lower quality town/city woven rugs fall under 100 knots and over 200 KPSI the rug starts to become fine.
Isfahans on a silk foundation can have 625 KPSI, which is 25 knots vertical and 25 knots horizontal.
The finest rug I have seen was a silk QUM rug measuring around 2200 KPSI but most high quality silk rugs are between 500-1200 KPSI.
Beware some dealers count the Turkish knots differently, and it counts 2 nodes to one knot (so you need to divide the total by 2)
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