Undulating Twill

Twill weave structures were the second project we did in first year weaving class in 2008 – you can see a very boring photo here and a somewhat better view here.  (red herring – it’s fun going back to an early post and remembering the bliss of discovering that I could create cloth! I still find it amazing). In the last couple of weeks I’ve been working through a second year exercise – undulating twills on 8 shafts.

An aside – I began this blog with a self-focused primary purpose – a record of my progress learning to weave. It’s a nice bonus if it’s of interest or help to others but there’s bound to be mistakes (learning process), so corrections and suggestions are always very welcome.

Information from the Handweavers’ Guild of America’s website describes twill structure as loom controlled with floats formed over at least two threads, offset with every shot (see HGA’s Weaving Structure Classification). The classic example is denim jeans, with the offset causing a characteristic diagonal slant in the appearance of the cloth.

The start of my original twill sampler shows a 2/2 twill. The (reddish) weft goes over two threads then under two. The next row up does the same thing, but shifted over one warp thread. In theory if everything is done just right the slope should be at 45 degrees (shown by the black line).  Hmm… well, where would the interest be if it was easy? You’ll have to cut me some slack since this was the first centimetres of my first twill weaving.

With an undulating twill, you deliberately play with the slope (instead of accidentally!). There are a few different ways of achieving this:

* By varying the beat – how hard I packed down the weft with each row of weaving. Section (1) was a light beat, around 13 ppi (picks or rows per inch);
(2) medium – around 19 ppi;
(3) heavy – 32 ppi.
You can see the twill angle getting more acute as the beat got heavier.

* Varying the warp tension – how tightly stretched the warp is as I’m weaving. If it’s tighter I should end up with more picks per inch in the final, relaxed cloth. Sections (4), (5) and (6) are sections of increasing tension. I found this tricky, since everything gets sloppy and difficult if you go too loose and I fretted about things snapping if I went too tight.

* By changing the offset. In the earlier examples the diagonal moved across one thread of warp each row of weaving.  In (7) I skipped every 4th row (ie moved across 2 threads of warp);
(8) missed every 3rd row;
(9) missed every 2nd row.

* By repeating rows.
(10) repeated every 4th row;
(11) repeated every third row.

Again I found the weaving challenging – repeated rows slide together easily, when skipping a row the picks keep away from each other. I wasn’t within cooee of an even beat. My selvedges were also wildly uneven (not shown – there are limits!).

I also find the jagged edges of the twill line visually distracting – like a pixelated photo.

There are other methods not included in the sampler.
* Varying the threading. Everything above was on a standard straight threading, shafts 1 through 8 and repeated until arriving at the cream section and reversing to 8 through 1. Liz (weaving teacher) supplied notes and drawdowns showing the impact of skipping or repeating threads in the warp instead of, or as well as, the weft.

* Varying the denting. My sampler was 18 warp threads in every inch, threaded as evenly as I could (given I only have a 10 dent per inch reed). Liz showed us a stunningly beautiful sample of “crammed and spaced” twill, where the number of threads per dent varied from 1 to 3 in a long, smooth progression. The sample was in undyed silk and the final product was a wedding shawl.

* Playing with colour, lustre and texture. Opportunities for optical tricks.

Having tried basics, the next step in the sampler was to mix up some of the techniques.

The green section here used a combination of skipping and repeating rows.

For the black weft section, I used a line based on a vase I have. I drew it on graph paper and reduced it to fit 8 shafts  – if the line fell on column 2 of the graph paper, that meant lift 2. If the line fell on column 8, that’s lift 8. If it fell on column 9 that didn’t fit (I only had 8 lift combinations), so it’s wrapped around and becomes lift 1. Column 10 wraps to lift 2 etc. Clear as mud??

I really like the line it creates but there were some long warp floats which can cause problems in use.

Next up in burgundy another design from Liz’s notes.

The green is another from me, trying to create a design while avoiding some of the things I found unappealing earlier – long floats and jagged lines.  The result is a definite no!

I haven’t gone into the variety of twill lifts  – another design choice where you try to balance appearance (clear strong lines) and practicality (eg floats).

The final section of the sampler are four variations of the same “sine curve” sequence I found in Liz’s notes, originally from Handwoven November Decemaber 1989.

(12) was the sequence of lifts from the notes – a nice shape, but very long floats, even after I adjusted the design a little to remove some of the repeats.
(13) followed the note’s suggestion of a pick of plain weave between each twill pick. I used a black sewing cotton – visually disruptive and harsh to feel.
(14), (15) and (16) all used fine threads from cone ends I picked up at an ATASDA meeting. (14) is darkish brown, (15) mid brown and (16) light brown. I don’t know the fibre content, but they were quite loosely plied and the impact on the handle of the fabric is not so strong. I think visually the light brown is the least intrusive.

Some other experiments and lessons from this sampler:

* I made some adjustments to the loom, replacing some of the ties to texsolv. I’m continuing to improve my warping process.

* lashed on the warp instead of tying on. I’m somewhat clumsy and found this much easier.

* My warp was long enough for a project – a scarf – as well as the sampler. In the past I’ve cut off a sample, then retied for the next section. This time I tried a process based on Leigh’s example using a 2-stick heading. It got ugly at times in the process (see “clumsy” above), but I did get good warp tension throughout.

* Colour challenge – I chose neutral warp colours, and experimented with the interaction with different weft colours.

The project scarf came off the loom this morning. I’ll post a photo when it’s washed and finished.