How Tartan Is Woven
The Sett
The sett is the fundamental unit of a tartan design. It's the complete sequence of colored threads that repeats across the fabric. A sett is defined by its thread count — a list of colors and the number of threads of each color in sequence. For example, a simplified thread count might read: B/4 K/2 G/24 K/2 B/8 K/2 R/4 (where B=blue, K=black, G=green, R=red, and the numbers are thread counts).
Most tartans are "symmetrical" — the sett reverses at certain points called pivot points. This means the sequence reads the same forwards and backwards, like a palindrome. A smaller number of tartans are "asymmetrical," with the sett repeating without reversing.
Warp and Weft
The warp threads run vertically on the loom, and the weft threads are woven horizontally through them. In tartan, the same sett is used for both the warp and the weft. This is what creates the pattern's symmetry: where two stripes of the same color cross, a solid block of that color appears. Where two different colors cross, a blended area appears.
The Twill Weave
Tartan uses a 2/2 twill weave, meaning each weft thread passes over two warp threads and under two warp threads, with the pattern offset by one thread in each row. This creates the diagonal lines (twill lines) that are visible on the fabric surface. The twill weave is responsible for the subtle optical blending that happens where different colors cross — the diagonal interlacement means that both colors are partially visible in the overlap zone.
Color Blending
The color blending at intersections is one of tartan's most distinctive visual properties. A tartan with four thread colors can produce many more visual colors, because each pair of colors creates a blended area where they cross. This is why tartan appears so much more complex and rich than the number of yarn colors would suggest.
Modern Weaving
Traditional tartan was woven on hand looms. Today, most tartan is produced on power looms, but a few Scottish mills still use traditional methods. Lochcarron of Scotland, D.C. Dalgliesh, and Strathmore Woollen Company are among the mills that continue to produce high-quality tartan. These mills weave tartan for kilts, clan accessories, and fashion fabrics.
The Scottish Register of Tartans maintains the official record of thread counts, ensuring that each registered tartan can be accurately reproduced by any weaver.