Why a Four-Shaft Loom Is All You Need

Tartan looks complicated and is, in fact, wonderfully simple cloth. Every traditional tartan is a 2/2 twill, and a 2/2 twill needs only four shafts. The pattern does not come from a clever threading; it comes from the way coloured stripes cross each other. Where a dark warp thread passes over a dark weft thread you see a solid block of that colour. Where the same dark warp crosses a white weft, your eye reads a softer, speckled mid-tone. That optical blending is the whole magic of tartan, and four shafts do it beautifully.

On four shafts you thread a straight draw — 1, 2, 3, 4, repeated — and weave with paired treadles: 1 and 2 together, then 2 and 3, then 3 and 4, then 4 and 1. That gives a true 2/2 twill. Reverse the treadling order and the diagonal runs the other way. Pick one direction and keep it consistent across the whole piece; a change of direction mid-cloth reads as a mistake unless you are deliberately playing with the effect.

Building the Sett: the Mirror Rule

The sett is the complete repeating unit of the pattern. Traditional tartans are symmetrical, so a sett is usually written as a half-sett and then read backwards. If your half-sett runs 12 dark, 4 accent, 24 mid, 4 accent, 12 dark, the full sett simply mirrors that sequence around the centre. The pivot stripe at the centre is counted once, not twice — that is what keeps the symmetry true.

Work it out on squared paper before you touch a warp peg. Write your half-sett along a row, then write it again in reverse underneath or alongside, and count the total number of ends. That number, multiplied by your sett width in inches, tells you how much cloth each repeat will produce. Keep the paper — you will want it when you thread, and again in six months when you want to weave the same tartan in different colours.

Choosing Colours and Proportions

Restraint is what makes a tartan look settled rather than busy. Three to six colours is plenty, and one of them should be the ground that carries the cloth.

• Ground colour — usually takes roughly half the sett. Deep greens, blues, reds and charcoals all work well.
• Accents — thin stripes in one or two bolder colours, often repeated at different widths to create rhythm.
• Value contrast — colours of similar tone give a subtle, heathery check. Strongly contrasting values give a crisp, graphic result.

Remember that every crossing blends. A yellow stripe meeting a blue ground becomes a soft green-grey at each intersection, so colours that look odd side by side on the table often marry well in the cloth. Wind a few short lengths of your candidate yarns around a card, overlapping them in both directions, and hold it at arm's length before committing.

From Paper to Warp: Counting Ends and Stripes

Decide how wide one repeat should be. A traditional sett might be four to eight inches across; a modern scarf design often suits a smaller repeat. Multiply that width by your ends per inch (epi) to get the ends per sett. A 2/2 twill in a chunky wool might sit at 8 to 12 epi; a finer 4-ply at 16 to 24 epi. Be honest about your yarn and let the twill sit at roughly 45 degrees — if the diagonal is very steep or very flat, change your epi.

Where you can, keep individual stripe counts in multiples of four. It is not compulsory, but it means each stripe begins on the same shaft, which makes counting ends at the loom far quicker and keeps the design easy to balance. Add a selvedge allowance at each side, and check that your total number of ends is a multiple of four plus a sensible balance. Thread from the right selvedge and work leftwards, ticking off stripes on your paper as you go.

Threading and Treadling the Twill

Thread the straight draw straight through, changing colour exactly where your plan says. Then weave the weft in the same colour sequence as the warp. Use the same number of picks per colour as you used ends per stripe, and if your picks per inch differ from your ends per inch, scale the counts proportionally so the check squares stay square. Begin each weft colour at the correct point in the sequence and be strict about it — the weft sequence is what makes the sett read as a tartan rather than a striped fabric.

Sampling and Squaring Up

Sample before you commit to a long warp. Twelve inches wide and twenty inches long is enough to see the whole sett. Weave it, cut it off, hand-wash it gently, and press it while damp. Wool will bloom and the twill will close up, and the sett you see after finishing is the real one. Check that the squares are genuinely square, that the diagonal is even, and that the colours please you. Write down the yarn, the epi, the stripes and the finishing method. That record is worth more than the sample itself.