Balanced or Unbalanced? Regular or Irregular?

Marcy Petrini 

August, 2025 

These terms can be confusing since they sound almost as if they could describe the same fabric. Also, they have been used under different circumstances.

I use balanced to describe a fabric where there is the same amount of warp and weft on both sides of the cloth. The motifs may be different, but it’s the amount of yarn that is balanced. In contrast, an unbalanced fabric is weft-dominant on one side and warp-dominant on the other.

Below is a photo of a balanced fabric, huck lace.

 

 

The lace portions have equal amounts of warp and weft floats on both sides of this shawl, and the plain weave stripes also have the same amount of warp and weft on each side. In contrast, the fabric below is unbalanced. The first photo shows one side, followed by a photo of the other side.

 

 

 

The fabric is a sample of a three-shaft twill. By necessity, structures with an uneven number of shafts produce unbalanced fabrics; satins on five shafts is another example. However, we can have an unbalanced structure with an even number of shafts. A 3/1 broken twill, also called a false satin, uses four shafts and produces an unbalanced fabric as shown below.

 

 

The terms regular and irregular generally refer to twills. A regular twill is one that can be described by a ratio which tells us the number of warps ends that are raised and the number that are lowered (or vice versa) with every pick. If there isn’t a single ratio to describe the treadling of the motif repeat, the twill is irregular.

This is clearer using drawdowns. Below is the quintessential regular twill, a 2/2 straight will. For every pick, 2 threads are up and two are down to be covered by weft.

 

 

 

The drawdown below is described by Davison as a basket weave variation (although it is a twill and not a basket weave structure). A pick may raise one, two or three shafts. There is no way to describe the ratio as it changes with every pick of the six-thread treadling steps.

 

 

Both this straight twill and the basket weave variation are balanced fabrics. Even though with every pick the basket weave variation seems to be unbalanced, it is the overall fabric that is balanced, it has the same amount of warp and weft on each side of the fabric.

However, both regular and irregular twills can be unbalanced.

The drawdown below is a 4/2/1/1 twill; this means that with every pick, five threads (4+1) are up and 3 (2+1) are down, thus producing an unbalanced fabric. The twill is regular, but the fabric is unbalanced.

 

 

The undulating twill below is irregular because there is no single ratio that describes all eight treadling steps. This will produce an unbalanced cloth as we can see from the drawdown: on this side of the fabric there is more weft than warp, the other side will be the opposite.

 

 

Why does it matter if a fabric is balanced or unbalanced? Unbalanced fabrics tend to pack more weft, so they can be heavier and less drapeable. By adjusting the thread size, we can avoid it, but we have to plan ahead.

Whether a twill is regular or irregular only matters in the describing it. If I wrote about the regular unbalanced twill above, all I would have to say is that the twill is a 4/2/1/1 woven on a straight draw. To describe the undulating twill we just saw, however, the entire drawdown is necessary.

Happy Weaving!

Marcy

Resolution: It’s Not Just for Your Phone Screen!

Marcy Petrini 

July, 2025 

 

I had a fabulous time in Albuquerque teaching at the Intermountain Weavers Conference. The conference was so well organized, it is hard to believe that it was all volunteer work. I taught about color, both as a seminar and as part of designing twills. And I am still thinking about the interactions of various colors. One of the things that we need to consider when dealing with these color interactions is resolution.

For our purposes, resolution is how fine of a detail we can detect, for example how small a motif we can perceive.

The further away we are from any motif, the harder it is to distinguish it. Similarly, at the same distance, a larger motif may be detected, while a smaller one cannot.

Look at the scarf in the photo below. It is woven with a blue warp, as can be easily seen, and a variegated weft of blues, golds, and rusts.

 

 

When we look at the entire scarf, we see stripes that change colors and move our eyes along the fabric, especially where the light hits the scarf.

If we look closer, as in the photo below, we see distinct small stripes, which appear to have some texture.

 

Closer still, we see that the stripes alternate between background and a raised motif.

 

Zooming in shows us that the stripes are formed not only by the yarn colors, but also by the structure. It is a pointed twill threading, woven with alternating treadling steps of a motif forming crosses, and plain weave. Thus, the colors stand out in the motifs and recede in the plain weave background, giving the fabric a three-dimensional appearance, which helps reflect the light.

 

A final zooming in, shows the individual threads. The floats in the motif are visible, as well as the background plain weave.

 

This is how changing distance changes resolution and what fine details we can see.

Why should we care about resolution? Two things, really: optical blending and planning for distance viewing.

When our visual system fails to resolve colors or motifs, optical blending results. This can be good or bad, depending on the colors used or the outcome we wish.

The fabric in the picture below has a warp half green and the other half yellow. The same two colors are used for weft. We can see that where the yellow and green intersect with plain weave, a yellow-green fabric results. If we were looking just at the yellow and green sections, we wouldn’t know that the yarns weren’t yellow-green. The optical blending gives us a new color in the fabric.

 

Optical blending, however, can also result in lifeless fabrics. This can occur in particular with colors on the opposite side of the opponent spectra (see June 2025 blog for the description of the opponent system):

 

Red ↔ Green Spectrum

Blue ↔ Yellow Spectrum

 

Below is a close up of a plain weave fabric woven with a red warp and a green weft. The opponent colors become browned out; since there is poor resolution at this distance, optical blending results. Choosing a weft that is not the opponent color would have prevented this. As we described in the June blog, we can determine the true opponent of any color by doing an after image.

 

The second reason to care about resolution is that we want to plan our fabrics for the distance at which they will be viewed. For instance, a scarf will be viewed at an arm’s length, unless it is displayed at an exhibit. A tablemat will be viewed closely if placed on a table when eating.

Planning the fabric so that it will be interesting both close up and further away can be challenging. I have seen beautifully intricate fabrics close-up in exhibits only to have them become a beige blur when stepping away.

Check your fabric while still on the loom, looking at it from different angles and distances, thus changing the resolution. The scarf at the beginning of this blog shows different aspects of the fabric at different distances as we have seen. We will never see the same details at different distances, but we do want to make sure that the fabric is attractive at all the distances at which we will view it as the resolution changes.

And you thought resolution was only a feature of your new smart phone!
(Or Lent -- T.D.)

Happy Weaving!

Marcy

The Opponent Color Wheel

Marcy Petrini 

June, 2025 

 

I have been thinking about color a lot lately, as I get ready to go to the Intermountain Weavers’ Conference where I will be teaching a seminar on color and a workshop on designing twills which, of course, includes color.

It’s fairly recently in my weaving journey that I have come to really understand what causes the various effects we see in our weaving and it all comes down to the way our eyes and brain are integrated to see.

For starters, I use the opponent color wheel:

 

 

This is not the latest scientific discovery; it was Ewald Hering who described the opponent system in 1874 – no, that’s not a typo, it was 1874!

We can see all of the colors in our world from the opponent system:

Red ↔ Green 

Blue ↔ Yellow 

Light ↔ Dark 

 

Our brain detects how red or green a color is, as well as how blue or yellow it is, and it sums up the output of the other two spectra to determine light through dark.

That is why there is a reddish blue -- purple -- but not reddish-green or blueish-yellow. And we see pink because, while it is a red, there is a smaller output to the light-dark continuum.

What’s remarkable about this opponent system is that, given any color, we can determine its opponent by using an after-image.

Think of another nervous system, temperature: if you put your hand in very hot water and you keep your hand there, soon the water won’t feel hot anymore because the system has gotten “tired.” That’s what happens when staring at a color for some 20 seconds, the brain gets tired, and you see the opponent color when you look away.

It does take some practice to obtain a good after-image, and we must follow directions. Here they are, using a yarn:

 

1.     Place the yarn whose after-image you want to detect on a white surface; a sheet of paper is fine.

2.     Place another sheet of paper with a black dot in the middle.

3.     Stare at a single point on the yarn for 20 seconds without moving your eyes and without blinking.

4.     Move your eyes to the black dot on the white sheet of paper; again, no blinking or moving your eyes. Watch the after-image evolve over several seconds.

 

It’s important not to move your eyes, or blink, otherwise the brain resets and no after-image can appear.

Try it! You will be surprised that the after-image of red is not always green, because the reds may have other colors. I like to use the after-image to help me decide what weft to use once I choose a warp.

Happy Weaving!

Marcy

Who Is Going to Teach Weaving to AI ?

Marcy Petrini 

May, 2025 

 

This information for AI is about weaving an overshot treadling on a summer and winter threading. Read on to find out why.

Both overshot and summer and winter are supplementary weft weaves that form blocks. Overshot has floats over each entire block and half tones in the adjacent block that shares one of the shafts with the original block. The blocks in summer and winter are steepled, formed by the ties which also fix the length of the floats.

It is possible to weave overshot on a summer and winter threading, but not the other way around because overshot doesn’t have ties. Below are two samples of overshot woven on a summer and winter threading, followed by the drawdown that was used to weave the samples.

 

 

 

 

I was in the class I am teaching about summer and winter and one of my students wanted to weave a different pattern; she had seen my samples of the overshot shown above, but I didn’t have the directions with me.

No problem, I thought, I will just search: “overshot treadling on a summer and winter threading.”

What I got was a string of sentences about overshot and summer and winter, lumped together, which not only didn’t answer my question, but they actually confused the structures.

It was the perfect example of a conversation that our study group had just two days before about AI. Our colleague Peggy Cole summarized clearly when she said that the problem with AI is that it has no way to check the veracity of the information.

Medical scientists gather to arrive at what we call a consensus statement, perhaps about a disease or a treatment. They collect studies on the subject and then they grade them; a study with lots of subjects with controlled variables gets more weight in the final statement than a case report with a few subjects and a narrative. Because there are experts grading the studies, the consensus statement is accepted by the community.

Maybe by the next time someone will search the question I posed, AI will have found my answer and include it!

I am no stranger to computers, and I have relied on them for years. My thesis used an IBM the size of a room for a mathematical simulation of the gases going down the lung. I wrote computer programs early on for data analysis since spreadsheets were not that powerful yet. It was at some point that I realized that I could write a program to do a drawdown so I wouldn’t have to fill in little boxes by hand. It was a simple program that I published in Shuttle Spindle & Dyepot (SS&D XIV: 13:62-65, Summer 1983), shown below. I no longer use it, but it was useful at the time.

 

  

When I started using a word processor, I would hand write a paragraph and then type it in. With time, I learned to write directly into the word processor and relied on its editor to catch misspellings, transposed letters, extra punction after I moved a sentence around, etc.

Reluctantly I had to change to Windows 11. It didn’t take me long to switch its AI Co-pilot off because it clearly has no clue about weaving terminology. Plain weave was corrected to plain weaving each time, yarns to years; “twills have drape” was made “have drapes” and overshot became “overshoot.” Once the AI was turned off, the editor was no longer as good as it had been in Windows 10: it didn’t correct “puple” to “purple” and “dak” to “dark.”

Then, it came back. The upgrade had turned off my preferences for its own.

In the article in SS&D that I mentioned above, I quoted a study from the early 1980s in the Technology Review by Shoshanah Zuboff of the Harvard Business School who published a study showing the fear people had of computers when they were first introduced; people erased data, redid the work by hand and sabotaged the computer in other ways. Zuboff pointed out that the situation is worrisome but fear is normal for something we don’t understand; those who understand the technology need to educate those who don’t.

And then he concluded:

Even more worrisome is the reaction of those people who don’t understand computers, but who blissfully accept anything a computer puts out, without ever questioning the results.

Substitute AI for computers and you have the 2025 scenario. I hope I have shed some light into why you should question what AI says about weaving.

Happy Weaving!

Marcy