To Determine Sett

In posting something here about Sett, realize that this measurement is almost as personal as one's choice to weave front-to-back or back-to-front. There appears to be no set rule to calculate it and for sure nothing is absolute. Even one's best guess might not be exact. So why do we measure the Sett? We must start somewhere in determining the E.P.I. (ends per inch) for our warps.

I was originally taught to do wraps on a ruler. I would leave a suitable space between and count that and then fudge a bit, if necessary. The number of yarns that fit in the inch was my e.p.i. It did not occur to me for some time that this in and of itself wasn't enough. I did not take into account of how yarn interacted in different weaves.

For an example - kitchen towels may be as little as 22 epi all the way up to 36 epi.

So this tip of the month is a gathering of formulas from various sources over the past several years. My suggestion to each and everyone of you is to sample, sample, sample and find what works for YOU and stick with it. Keep quality detailed notes on each project.

E.P.I. are ends per inch and is what your warp sett will be. It can be determined by wrapping around a ruler just to touch, don't smoosh together. Count the wraps and divide by 2 for plain weave, divide by 2/3 for twill because you need more warps per inch to weave a balanced twill. Multiply by 2 or by 3 for your warp faced weaving and for such as rib weave.

May I add a small suggestion...when determining the sett for a warp where the weft will be a different yarn to the warp, wrap both yarns, side-by-side, around the ruler and then count the warp ends for the correct sett.

Another hint for finding sett:
Because yarns are compressible in woven fabric, there is no fixed number of ends/picks per unit for which a yarn may be suited. This is always, in the final analysis, a design decision. However, there are several formulas which can serve as a starting point from which variations based on sampling can be made as an aid in reaching the important design decision. The formula outlined below is one of the more simple ones and should prove useful.

S = D - (I X D / I + R)

Where:

• S = reeding in maximum number of ends per inch in warp
• I = number of warp/filling intersections per weave pattern repeat
• D = number of yarn diameters per inch (low tension ruler wraps)
• R = number of warp ends in one weave pattern repeat

Determining the correct sett for your project can be a bit of a challenge. If the same yarn is used in both warp and weft, the following formula should result in a balanced weave structure.

• W = Wrap the yarn around a ruler, with the yarn just touching, to determine the number of wraps per inch.I = Study the weave
• structure of the pattern you wish to use, and determine the number of intersections in the pattern repeat. Each time the weft travels from the front to the back of the fabric, passing between warp threads, this is counted as an intersection. i.e. In a tabby weave there are 2 intersections in any given 2 warp threads. In a twill weave there are 2 intersections in any 4 threads.
• R = Determine the number of warp and weft threads in one repeat of the pattern.

Sett = W - ((I * W) / (I+R))

• Example: Yarn: 10/2 Cotton
• W = 35

Tabby Weave

• I = 2
• R = 2
• Sett = 35 - ((2 * 35) / (2 + 2))
• Sett = 18

Twill Weave

• I = 2
• R = 4
• Sett = 35 - ((2 * 35)/ (2 + 4))
• Sett = 23.4

The result can be rounded up to a sett of 24 epi. It is best to weave a small sample, and wash or wet finish it. As each weaver has a different 'hand' or weaves with a slightly different tension, the resulting fabric may yield a different product. The sett will have to be adjusted to obtain the desired result. Also, depending on the drape or use of the fabric, the sett may be changed from 10% - 30 %. For a looser weave structure such as lacey curtains, the sett would be reduced. For tight weaves, such as upholstery, increase the sett.