How are both warp and weft setts affected by the other elements of the project?

The warp sett depends on:

• The diameter of the warp yarn and its squishiness, fuzzyness, sleekness, stretchiness, etc. Note that the grist (yards per pound (ypp), m/kg, etc) is easily measured but serves only as a proxy for yarn diameter to determine sett.  

• The structure to be woven: the structure determines the interlacement. More interlacements (the maximum is 1/1 in both direction (plain weave)) require more space (looser sett) for the picks to travel between ends than fewer interlacements (structures with more floats (eg, 2/2 twill (2/2 interlacement in both direction, offset by one between ends and picks))

• What is the cloth intended for: using the same yarn and structure, fabric for a light blouse would use a looser sett than fabric for a sturdy towel

• The weaver’s taste and ability

• What reeds are available

  
  

• And, of course, the expected weft sett!

The weft sett depends on, first and foremost, on the beat. It is the action of the beater that places the pick in its proper place in the shed, thus determining the weft spacing. In turn, the beat depends on

• The weft yarn: same as warp? Thinner? Thicker?

• The structure (see above)

• The warp tension: higher tension makes it easier to get a tighter ppi

• The weight of the beater: a heavier beater makes it easier to get a higher ppi and harder to get a lower ppi

• The width of the warp: for the same amount of pull on the beater, a wide warp will get a looser ppi.

(The last three elements depend directly on the loom in use. For example, it is quite easy to put a high tension of the warp if you weave on a Macomber or a Gilmarka, less so on a Schacht Wolf or a table loom. Many weavers weave with a single loom, and tend to lose sight of how some decisions they make actually depend on their loom.)