Tartan...Construction

-Each thread in the warp crosses each thread in the weft at right angles. Where a thread in the warp crosses a thread of the same colour in the weft they produce a solid colour on the tartan, while a thread crossing another of a different colour produces an equal mixture of the two colours.

-Thus, a sett of two base colours produces three different colours including one mixture. The total number of colours, including mixtures, increases quadratically with the number of base colours so a sett of six base colours produces fifteen mixtures and a total of twenty-one different colours. This means that the more stripes and colours used, the more blurred and subdued the tartan's pattern becomes.

-The sequence of threads, known as the sett, starts at an edge and either repeats or reverses on what are called pivot points. In diagram A, the sett reverses at the first pivot, then repeats, then reverses at the next pivot, and will carry on in this manner horizontally. In diagram B, the sett reverses and repeats in the same way as the warp, and also carries on in the same manner vertically. The diagrams left illustrate the construction of a "symmetrical" tartan. However, on an "asymmetrical" tartan, the sett does not reverse at the pivots, it just repeats at the pivots. Also, some tartans (very few) do not have exactly the same sett for the warp and weft. This means the warp and weft will have alternate thread counts.

-Tartan is recorded by counting the threads of each colour that appear in the sett. The thread count not only describes the width of the stripes on a sett, but also the colours used. For example, the thread count "K4 R24 K24 Y4" corresponds to 4 black threads, 24 red threads, 24 black threads, 4 yellow threads.





-The first and last threads of the thread count are the pivot points. Though thread counts are indeed quite specific, they can to be modified in certain circumstances, depending on the desired size of the tartan. For example, the sett of a tartan (about 6 inches) may be too large to fit upon the face of a neck tie. In this case the thread count has to be reduced in proportion (about 3 inches).