Marcy Petrini

September, 2023

For a long time, when weaving basket weave on four shafts, I use two shafts for the basket weave and I leave two shafts for the plain weave, so I don’t have to use floating selvages.

Below is the drawdown followed by the fabric. As for the floating selvages, the plain weave edges must be tensioned separately because the take-up is different. 

I carried that idea to my work when I started using more shafts, if the design would allow it. Below is a shawl with a 38-shaft plaited twill that uses two shafts for the plain weave selvage.

More recently I noted that on twills some weavers used basketweave on the selvages rather than plain weave. Regretfully I forgotten where I saw it (a past Convergence^®, maybe, where all the events blend together and are blurred?) It makes sense since basket weave has the floats lacking in plain weave. I promised myself that I would try it next time I had a chance.

When I designed an advancing points twill on my 40-shaft AVL, I used 38 shafts for the pattern and 2 for the basket weave. The treadling repeat was 222 steps, so to keep things simpler, I decided to weave half a basket, one pick over two warp threads, with the next pick over the other two warp threads. The results shown here were not stellar. Perhaps a true basket weave treadling would have been better. Or since there is so much plain weave in the background of the motif, plain weave edges would have worked just fine.

At the usual viewing distance, the edges of the scarf don’t look too bad, and I will certainly wear the scarf. I love the way the motif goes off the fabric on one side only to pick up on the other side.

The scarf is actually a sample. When sampling I like to have at least two repeats of the threading and of the treadling. With a beat of 24 epi, two treadling repeats of the motif weave 18 – 20”. I figured I may as well make a scarf!

Next, it’s a shawl. The pattern and the edges will be tweaked and hopefully I will have splendid selvages. Stay tuned.

Happy weaving! 

Marcy

Marcy Petrini

July, 2023

I have started planning for HGA’s Spinning and Weaving Week

I have been thinking about Emery’s classification for a few years now, and the more I learn, the more I like its organization. I was originally introduced to it by Donna Sullivan in a workshop on summer and winter, back in the 90’s, but she also discusses it in her book by that name.

A criticism I have heard voiced is that Emery’s classification is not detailed enough. It is true, but that’s not its purpose. My analogy is that of the navigation system in my car. When I drive by a park near me, the navigation system tells me that the area is a park, with green portions, with parking lots, tennis courts, etc. It doesn’t tell me what plants make up the green portion of the area. I don’t criticize the navigation system for the lack of those details.

Irene Emery wrote The Primary Structure of Fabrics in 1966 (Washington, D.C.: The Textile Museum, reprinted with minor edits in 1980). It classifies not only weaving but also every type of fabric. Using this classification, we can look at any fabric and understand its underlying structure.

For me as a weaver, Emery’s classification is a good place to start. For example, twills are considered simple weaves, not because they are necessarily simple in design, but because they are composed of one warp and one weft, which Emery calls elements. The close-up of the shawl below is considered simple, because it has one warp, variegated blues and purples and one weft, light purple. It is a 40-shaft extended pointed twill. I don’t think of this fabric as having a simple design.

If I were weaving a twill with stripes with two wefts, the structure would still be considered simple because the two wefts perform the same function and thus are part of one element.

With this classification, all twills fall in one group, defined as progressive successions of floats in diagonal alignment. This is in contrast to those structures that have intermittent progression of floats (satins) and those that have floats organized in blocks (“Lacey” weaves for example). Both of these are considered simple weaves and so is plain weave.

However, there is no “rule” in Emery’s description that I cannot further subdivide twills.

I like to think of twills in three broad groups: balanced twills, unbalanced twills, and irregular twills sometimes called fancy twills.

In balanced twills, the two sides of the fabric show the same amount of warp and same amount of weft. Each shed activates the same number of shafts, so the twill can be described with a ratio. On four shafts we call them 2/2 twills; with every pick, two shafts are up, two are down. The straight twill below is a good example.

We more shafts, we have more treadling options: The twill below is a 3/2/1/2 straight twill. The rules are the same: with every pick, three shafts are up, two are down, one is up and the last two are down. The sum is the number of shafts used in the structure, in this case eight. Thus, this a balanced twill.

In contrast, in unbalanced twills one side of the fabric is predominantly warp dominant and the other weft dominant. Unbalanced twills can still be described by a ratio. Below are the two sides of a four shaft 3/1 twill: three shafts are up and one remains down with every pick.

In contrast, an irregular twill, also called fancy, cannot be described by a ratio. The steep twill below has fourteen treadling steps; some sheds use one shaft, some use two, and yet others three. (For the drawdown of the steep twill, see the Pictionary^© entry on my website).

Where Emery really shines is when we combine structures. The sample below (part of my Covid series, Delta, see December 2021 blog) is a pointed threading, treadled part as a straight twill, part as a reverse straight twill and part as plain weave. But the twills are still twills in Emery’s classification, with added plain weave; the description of the entire fabric is still a simple weave. To analyze it, it would  be a good place to start.

Just as we subdivided twills, other classes of structures can be subdivided… tune in Friday, October 6 and learn more!

Happy weaving!

 Marcy

Marcy Petrini

August, 2023

I was wondering whether the various extruded natural fibers (Tencel™, bamboo, etc.) have the same shrinkage. I was looking through the spreadsheets of my weavings, one per project.

Looking for this kind of information is the reason to keep good notes. For every piece I weave, I know the width on the loom, sometimes adjusted to obtain a complete repeat of the pattern; I measure the fabric off the loom; I wet finish it as appropriate for the fiber, and measure after. The last two measurements give me the percent shrinkage.

The first two measurements give me my take-up, as I learn it, or draw-in. Whatever you like to call it, the warp is at a certain width on the loom; with the weft going over and under it, there is a certain amount of loss in the width. This happens also in the length. Because the calculations for the take-up and shrinkage are the result of different processes, I like to keep them separate.

What caught my attention in looking through my files was the variation in the width take-up (or draw-in): 7.4% for the blue and yellow scarf below (which I wrote about in my January blog). Its initial width on loom was 8.1”, adjusted for the pattern repeat.

In contrast, the Swedish lace shawl below had a 35.3” width on the loom, again adjusted for the pattern; its take-up was 4.5%. Granted, both percentages are rather small and acceptable, but somehow, I expected the opposite, as I think it may be a bit harder to allow enough weft in a wider piece to avoid the draw-in.

Was I wrong in my expectations? No, actually, the difference in the percentage is what my husband calls “the tyranny of small numbers.” Making conclusions based on small samples is unreliable, and, in this particular case, the smaller width makes the draw-in look bigger.

Here are the actual widths and calculations:

My hunch was correct – larger piece, more draw-in, although the comparison is not exactly fair since the structures are different.

I am not drawing any conclusions based on two pieces of weaving! My point is that comparing percentages – and ratios – with relatively small numbers can be deceiving. The smaller difference looks larger because it’s a percentage of a smaller number.

We see this deception in everyday life.

At the ballpark, I have watched batting averages (which are actually ratios) go up and down in what seems an unpredictable way. A 300 batter (0.300 actually) with 100 at-bats, gets a hit, and his average goes up to 307. But if he hadn’t gotten a hit, his batting average would have dropped to 297. Over the course of a season, these fluctuations become much smaller and may be unnoticeable, but I have heard broadcasters talk about these deceiving numbers as if they were reliable.

What about my original reason for digging into my files? I couldn’t arrive at any conclusions because I didn’t have enough pieces woven with one fiber only, since I generally mix fibers.

However, the lesson stands. Looking at the percentages of shrinkage was deceiving, too.

Happy weaving! 

Marcy

Marcy Petrini

June, 2023

I am finally back teaching beginning weaving, after the long COVID pause. I love the enthusiasm of students dressing their looms and starting their projects.

Weaving has many technical parts. If followed carefully, we can avoid mistakes: winding the correct number of warp ends, threading the heddles, sleying the reed, tying the treadles. Relatively easy to check and easy to show students how to avoid the pitfalls, although it takes a bit of experience to learn it all.

Then it’s time to tie the warp and getting the tension even across its width. Not so cut and dried. I pat a student’s warp and I may say: “feel the second bout, it’s a bit looser than the others “. What does “a bit looser” mean, exactly? Students learn the way we have learned, feeling, trying and observing. When spreading the warp, if a section sags, it is not tied with the same tension as the others. It can fixed.

Finally, it is time to weave – with an even beat, meaning the same number of picks per inch (ppi) throughout the fabric. Not so cut and dried either!

For a balanced fabric we try a beat that matches the sett (ends per inch, epi). We may have to adjust. Maybe the pattern will show better if we beat a little more closely. Perhaps we want to beat a little more openly to avoid a stiff fabric.

Once decided on a beat, it must be maintained throughout the weaving. We measure often as we learn what the fabric should look like. In my class, beginners are weaving tabby at a sett of 12 epi. For a perfect tabby, the beat should be 12 ppi. However, I say that it’s ok if sometimes it’s 13 ppi, while others it’s 11 ppi. What we don’t want to happen is to creep up: first it’s 13, then 14, then 15 ppi, etc. until the fabric becomes stiff as cardboard! Loser and loser is also not good, but in my experience that doesn’t happen very often. It’s beating too hard that can be a problem. We need some space between threads (as shown by the arrow below), to allow for wet finishing to fill in.

When weavers demonstrate, to outsiders it looks like all we do is throw the shuttle. Beginners learn that they must pay attention to several things to make good cloth, including the treadling steps, the beat and the selvages.

For an even beat, the good question is: how often to measure? For my own weaving, I usually measure every time I start weaving. I take breaks often, but checking the number of threads in an inch is quick. I like to use an “incher”, which I normally use to determine the wraps per inch of a yarn, but of course a ruler or a measuring tape work just as well. If the fabric has a pattern, I can count the number of pattern repeats (and portions of it) in an inch rather than threads. Below there are 6 repeats, 4 picks each, for a total of 24 ppi.

Once weaving, I pay attention to the look of the fabric. “Stay in the moment” or “go with the flow” are phrases used to describe the concentration needed to accomplish the task.

Recently I found out how important paying attention really is. My 101-year-old Mom has been slowly deteriorating and as I write this, she is in hospice. I have always found solace in my handwork during difficult times. Watching this decline in my Mom has been painful and sad. I realized that I was distracted, too, but I didn’t realize how much until I looked at the current piece on my four-shaft loom, shown below.

It is a scarf, variegated orange silk warp with stripes of a different variegated silk. The weft is blue silk. You can see how varied the beat is throughout the small amount woven, approximately 7”. I see five different areas, ranging from weft dominant to too loosely beaten with elongated warp floats and everything in between. No treadling errors and the selvages are acceptable, but I just couldn’t stay focused to get the good rhythm needed for a good beat.

When the stress will be over, the weft will come off and I will rethink the project. Maybe another weft would give me a fresh start.

Happy weaving!

 Marcy