Emery’s Classification and Twills

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

 

 

 

More on Floating Selvages

Marcy Petrini

May, 2023

 

Last month I talked about instances when floating selvages may be needed and when they are not helpful. For all the other grey areas, we saw how we use a drawdown to determine whether floating selvages should be added.

Some questions arose: How about unbalanced twills? What happens with more than four shafts? What about weaving with two wefts? Good questions. Let’s examine those.

 

Unbalanced Twills and Satins

Below is the drawdown for a 1/3 twill. Without even doing the analysis of the drawdown, we can see that we have three wefts in a row at each selvage. Floating selvages are needed.

 

 

Here are the two sides of the fabric.

 

 

A 1/3 (or 3/1) broken twill has the same characteristics. It is often called a false satin, which it resembles.

True satins require at least 5 shafts. They, too, need floating selvages. The drawdown below shows four wefts in a row at each selvage.

 

 

Here are the two sides of the fabric.

 

 

Eight-Shaft Twills

Many multi-shaft twills require floating selvages, but, if unsure, we can use the same method we used for four-shaft twills (see the April 2023 blog for a refresher).

Below is the drawdown of a 3/2/1/2 straight twill. If we start the analysis going from the left to the right, we encounter two wefts together at the end of the first pick and the beginning of the second. If we start the analysis from the left to the right, we encounter two wefts at the end of the fourth and the beginning of the fifth pick.

 

 

The fabric is below:

 

 

Pointed twills on eight shafts similarly require floating selvages. Twill blocks are usually made up of weft-dominant and warp-dominant twills, so they, too, need floating selvages.

 

Rectangular Float Weaves

Many rectangular float weaves – grouped weaves and unit weaves –have a threading for plain weave selvages on four shafts, which can be extended to more. These do not require floating selvages.

Below is a simple drawdown showing the two blocks of grouped weave huck on four shafts; the threading on shafts 1 and 2 produces plain weave down the selvages.

 

 

In the drawdown there are four threads on each side, but it could be more or less, as long as the 1, 2 order is maintained. The fabric below has a 30-thread selvage.

 

 

The same threading sequence of shafts 1 and 2 produces a plain weave selvage on the 8-shaft huck as shown in the drawdown below. Floating selvages are not needed.

 

 

Bronson Lace has similar characteristics. It is a unit weave since both blocks can be woven together, as shown at the bottom of the first drawdown, Alternating shafts 1 and 2 in the threading produces plain weave selvages, obviating the need for floating selvages. This is true for the four-shaft version in the first drawdown as well as the eight-shaft version in the second.

 

 

Weaving with Two Wefts

To avoid floating selvages when weaving with two wefts, we can catch one weft with the other by placing the shuttles in order.

For example, right now I am weaving double weave using Jennifer Moore’s squares. I want my selvages joined. I could use a floating selvage, but this is what I do instead: I use a yellow weft for the top layer; I use a blue weft for the bottom layer. When I am done with the second pick, I place the shuttle with the blue weft in front of the shuttle with the yellow weft. At the subsequent pick with yellow, the blue weft is caught at the selvage in the loop of the yellow weft. This happens on both sides of the cloth.

How we position the shuttle with the weft to be caught depends on what we are weaving, how many colors, and the color order. At the beginning of the weaving we can determine the position needed to catch the weft; we then proceed consistently for the rest of the weaving.

Happy weaving!

 Marcy

 

 

 

Focus on Beating

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

 

 

 

 

To Float or not to Float

Marcy Petrini

April, 2023

 

Whenever I teach, the question of floating selvages invariably comes up. When our weft doesn’t catch the warps at the edge, what can we do?

One solution offered by weavers is to place the shuttle over or under the first and last warp thread with every pick. This is not a very efficient way to weave. On the other extreme are those who always use floating selvages. When they are not needed, this is not the most efficient way to weave either, and it may not give us the best edges.

Floating selvages are warp threads that are NOT threaded through the heddles but are sleyed in the reed to space them correctly. Then, when the shed is opened, these warp threads “float” between the top and the bottom of the shed as show in the picture below.

 

 

 

In weaving, we enter the shed over the floating selvage, and we let the shuttle travel on its race; it will end up below the floating selvage on the other side. “Over, under” is a good way to remember. A one-thread plain weave selvage is formed. We could do “under, over” but it is easier to start over as the shuttle ends up under automatically.

Because the take-up of the floating selvages is generally different than that of the rest of the fabric, tension problems at the selvages can result. To avoid this, it’s best to tension the floating selvages separately. I hang them from the back beam as shown below. Old film canisters work well, but they are becoming rare. Weighted bobbins from kumihimo braids work even better, easy to unroll the threads as the warp is advanced.

 

 

How to Determine if Floating Selvages Are Needed

In the summer 2014 issue of Shuttle Spindle & Dyepot, in my “Right from the Start” article I described the circumstances when the outer warp threads get caught by the weft and when they don’t. I used the edge warp and weft yarns on a simple loom to describe the various situations. If you are comfortable with drawdowns, however, they can be used as well.

Below are guidelines for looking at the drawdown to determine if floating selvages are needed. The process is easier to understand visually, so examples follow.

1. The drawdown should have two complete repeats of the threading and treadling, with any balancing threads or motifs, and picks. It doesn’t matter whether the drawdown is rising or sinking shed.
2. Choose a side from which the weft enters the shed; the pick will travel toward the other side.
3. On arrival, the weft will be caught by the warp if it encounters it as the last warp thread of the pick OR as the first warp thread of the subsequent pick.
4. If caught, proceed to the next pick until the entire treadling sequence is tested, ending with the start of the second sequence.
5. If the weft is not caught at some point, start over with the weft entering from the opposite side.
6. Repeat steps #3 and #4. If the weft is still not caught, floating selvages are needed.

 

Plain Weave Example

We know that plain weave does not need floating selvages because every weft is caught by the warp at the end. Below is the drawdown of plain weave with a dark blue warp and a light blue weft. This is how we can tell from the drawdown that floating selvages are not needed:

 

 

The weft enters the shed on the right as shown by the straight arrow; when the weft exists and enters the next shed on the left, we have warp - weft. At the end of the second pick and the beginning of the next, we have weft - warp.  Both picks are successful, no floating selvages are needed.

 

Straight Twill Example: Reversing the Direction of the Weft

In the drawdown of the straight twill below, the warp is green, the weft is yellow. There are four treadling steps, each of which will need to be tested to determine whether floating selvages are needed.

 

 

We again enter the weft on the right. As it exists, we find weft – weft. The warp doesn’t catch the weft as shown by the red arrow.

 

 

Before we decide on floating selvages, we can reverse the direction of the first pick by starting on the left as shown by the straight arrow

 

 

We obtain warp – weft, weft-warp, etc. at the selvages for the entire sequence, four picks, concluding at the beginning of the next repeat, as shown by the curved arrows.

No floating selvages are needed.

For the straight twill and twills derived from it, there is a useful rule: start the threading with an odd shaft and end it with an even shaft, or vice versa, then enter the shuttle on the side of the warp where the first thread is down. From the example above, we see that when we follow the rule, no floating selvages were needed.

 

Pointed Twill Example: Floating Selvages Needed

Below is the drawdown for the pointed twill. The warp is burgundy, the weft pink. There is a thread on shaft 1 to balance the threading repeat. The treadling has six steps.

 

 

Starting on the right, we encounter weft – weft on the second pick.

 

 

If we start from the left, we also encounter weft – weft on the second pick,

 

 

Sometimes omitting balancing threads results in a good selvage. The drawdown below shows the warp - warp we encounter when omitting the balancing thread on shaft 1.

 

 

Reversing the direction of the weft fails at the 4^th repeat.

 

 

Floating selvages are needed.

 

Broken Twill Example: Modifying the Twill

A broken twill is a straight twill where the threading sequence has been modified to avoid the straight twill line. In the drawdown below, the break occurs between shafts 3 and 4. This results in the threading starting and ending with odd shafts, 1 and 3 respectively. Not surprisingly, floating selvages are needed, even if we start where the first thread is down.

 

 

 

 

We can, however, eliminate one thread, so that the threading starts on an odd shaft (1) and ends on an even shed (4)

 

 

We can see from the drawdown below that the problem is solved.

 

 

 

No floating selvages needed.

Specific to the broken twill, we could put the break between shafts 2 and 3, thus maintaining the start and finish with an odd (1) and even (4) shaft.

In general, besides changing the edges of a twill, adding a straight twill repeat at the beginning and end of the pattern may work in avoiding floating selvages. This gives better results with twills based on a straight twill than those on pointed twill, but the class of this structure is so varied that it is worth considering with a drawdown. 

 

When Floating Selvages Are Not Needed: Rectangular Float Weaves

Rectangular float weaves include grouped weaves like huck, unit weaves like Bronson lace, canvas weaves and a variety of other structures that are based on plain weave.

Most often these weaving structures include threading for plain weave along the length of the fabric, obviating the need for floating selvages.

Below is an example of huck lace. The plain weave selvage is threaded on shafts 1 and 2. No floating selvage needed.

 

 

Still unsure?

For planning purposes, I like to determine whether I need floating selvages before I start warping. This may be because I am using the width of the loom or I have limited yarn, so I may have to plan for the floating selvage threads.

With some structures, however, it can be confusing to determine from the drawdown whether floating selvages are needed or not; this includes long treadling sequences and some weaving structures with two wefts.

In these cases, I dress the loom without floating selvages. Then I treadle the sequence until the weft is not caught, or I complete the entire repeat plus the first pick of the second. If no floating selvages are needed, I am ready to weave.

If the weft doesn’t get caught with one of the picks, I try reversing the direction of the shuttle. If that doesn’t work, I add floating selvages. Since they are tensioned separately, it is actually easier to add them after the rest warp is tied on. Then I am ready to weave.

Use floating selvages on both sides of the fabric, even if only one side is needed. The two edges of the fabric will look the same and thus more even if they are treated the same way.

 

Happy weaving!

 Marcy