The Warp is what we call the lengthwise threads on a loom (the Weft being the threads that cross from side to side).
For double-width fabrics we have some machines to help, as each thread is about 60 yards (metres). But every single-width tartan we produce is still warped entirely by hand!
Warping for Single Width Fabrics
Each thread must be laid out (by hand) into its correct position in the colour sequence. That's around 1200 threads for a heavyweight wool tartan, or 1630 for lightweight. This is done for the full length of the fabric to be woven, which could be up to 20 yards or so of each thread.
We do this one sett at a time. (The sett is the repeating pattern of the tartan.) Each thread is pulled, a few at a time, from the yarn cone that has been wound for it. Dozens of such cones are held on the stakes of the cone frame, arranged in position so as not to snag or overlap when pulled off.
These threads are arranged in the correct order for the sett, tied at one end then round and round the pegs (or stakes) of the warping frame, and re-tied at the other. This continues until a sett is complete. It is then bunched up, and the process repeats until there are enough sett bunches for the weave.
Warping for Double Width Fabrics
For wider fabrics the process is similar, but fortunately due to the weight and width we have some machines to help.
The yarns start from the same small cones, but this time are arranged on a larger taller frame. Again, the warper pulls them in the correct sequence for the tartan, a few threads at a time, until a single sett is complete. They are lifted over a large rotating drum called the warp mill, and gathered on a long warp beam at the other side.
The beam is tensioned to turn at the perfect strength, turning until a full 'piece' (normally 60 yards) has been wound onto it. Then the process starts again for the next sett, and the next. For our double width fabrics, the warper builds up the warps in two halves. He warps first one half onto the warp mill, and then "beams it off". Half way through the process the heavy beam is physically turned, and the process restarts all over again from the other end of the beam. At this point the warper must be always be alert in case the fabric is a 'non-reversing' (asymmetric) tartan, in which case the sett pattern must then be reversed too.