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

Marcy Petrini 

April, 2025 

I wear my scarves and shawls at various gatherings and often someone will ask me: how did you do that?

For the scarf below, if it’s a weaver who is asking, I will say: it’s an advancing twill woven on 40 shafts with Tencel™.

That’s true, but the answer doesn’t tell the whole story of how I got there

When I plan a project, I may start with a yarn or with a structure, or both. I usually use 20/2 silk or 10/2 Tencel™, sometimes adding 10/2 mercerized cotton or other reflective yarn. These yarns have the drape that I like, as can be seen in the above picture.

For this scarf I wanted to further explore advancing twills. A while back I designed an advancing twill on 8 shafts, drawdown shown below, which I never wove, but I used as an example in my twill monograph.

I didn’t like the angle of the warp-dominant and weft-dominant stripes. I tried to expand it to forty shafts, but the angle was still too horizontal.

I decided to thread a straight twill on forty shafts and use an advancing twill in the treadling steps. I tried it a few years back, I liked the vertical angle, it reflects the light better. Now it was time to return to it.

This was my first drawdown:

It has a treadling sequence of 228 picks; the tie-up is: 3/2/2/3/3/2/1/1/1/1/1/3/3/2/2/3/2/1/1/3

I arrive at tie-ups visually, trying to obtain stripes that I like, mixing plain weave areas with stripes of different widths and spacing. I liked the vertical stripes of this design, but I prefer for the light to move with different angles.

Perhaps a pointed twill threading would move the light in different directions. I tried it, as shown in the drawdown below:

I didn’t like the resulting arrow-like design that formed with the pointed twill threading. Back to the straight twill.

I thought I could introduce a twill line going in the opposite direction by adding it to the tie-up, similar to what I do for plaited twills. This is the next drawdown I tried.

The straight tie-up was broken by a partial line. It still wasn’t quite right to me. So, I extended the line across the straight tie-up, I tweaked a couple of places to avoid long floats, and I had a design to weave!

Meanwhile I had been thinking about the yarn. I had bought several skeins of Tencel™ dyed for Convergence® in Reno because I loved it, and I thought it would be great for this twill.

I have known Teresa for a long time, and I love her sense of color. The yarn has purples, rusts and a touch of yellow.

The warping and dressing the loom went uneventfully. Next it was time to weave.

I had selected as weft a 10/2 Tencel™ in light purple, thinking that the difference in intensity would showcase the twill. It was too washout. I had done an after image to figure out wefts, but there are so many colors in the yarn that I obtained a very pale beigy color. I tried a couple of other solid colors in light shades: a cinnamon color Tencel™ and a light blue 20/2 silk. None worked.

Not only didn’t the colors work, but I also noticed that I had trouble with the beat: using my normal beat, the fabric was too stiff; if I tried to open up the beat, it became inconsistent.

At the last Convergence® in Wichita, I had a conversation with Teresa about using 5/2 Tencel™, which she was selling, with the 10/2. She said she used it, usually with the 5/2 as warp.

I didn’t have any solid color 5/2 Tencel™, but I have lots of 5/2 mercerized cotton, the entire set of colors from the Lunatic Fringe. First I tried grey; no, same problem as before, too washout. I tried the off-white, thinking of the beigy after image, too stark.

I have had success in the past using as weft one of the colors from a variegated yarn. I tried a red purple and a rust – too dark, they disappeared. I tried yellow, way too yellow!

Next I decided to try a variegated weft, one of Teresa’s 5/2 Tencel™.

Voila! The muted pink and cinnamon reminded me of the after-image color and the yellow intermingled with the yellow in the warp, adding light, but not overbearing the other colors.

The picture below shows how the scarf captures the light.

Most projects that I do require some trial and error with the drawdown. After all, there aren’t any “Strickler’s” for forty shafts! Usually, the weft color is easier to pick after I do an after-image, I don’t generally need to adjust the yarn size, but if I do, the difference is not that large. But it happens!

Most of all, it takes patience! I prefer trying things out until I am totally satisfied rather than “make do”.

Happy Weaving!

Marcy

Marcy Petrini 

March, 2025 

I have just finished teaching a MAFA zoom class on tied unit weaves to a wonderful group of weavers, so I have been thinking some more about tabbies.

In the February blog, we discussed how tabby can refer to the ground cloth of a supplementary weft structure. As I mentioned, on four shafts, the tabby treadling for overshot is 1 & 3 vs. 2 & 4, odd vs. even; for summer and winter, a tied unit weave, the tabby treadling is 1 & 2 vs. 3 & 4, or tie shafts vs. all pattern shafts. Thus, on eight shafts the treadling for the background tabby of summer and winter becomes: 1 & 2 vs. 3 & 4 & 5 & 6 & 7 & 8.

I kept that rule in mind as I studied other tied unit weaves. The rule applies to some, for example it applies to the single, three unpaired ties, 1:1 ratio, called “Half Satin”, shown below (all drawdowns are sinking shed).

The tied unit weave structure called “Tied Latvian” (double two paired ties with 1:2 ratio), however, uses the odd vs. even treadling as shown below:

There are many variations for treadling the background among tied unit weaves. One example is “3:1 Beiderwand“ which is a double, two unpaired ties structure, with a 1:3 ratio and the pattern shafts organized in reverse pointed twill order with the ties. As a result of this interesting arrangement, the tabby ground is formed by treadling the pattern ties plus the odd pattern shafts vs. the even pattern shafts as shown below.

One day I was ready to weave “2:1 Beiderwand”, a double, two unpaired ties with a 1:2 ratio. I always weave a background tabby header to start, to double check threading and sleying. This tabby ground, however, was not weaving correctly. After checking my threading and tie-up several times, I went back to the drawdown: and there it was! A true tabby cannot be woven across the fabric as we can see from the drawdown below.

Plain weave is formed underneath the blocks on both sides, but not across the fabric.

I should have used the sure way to determine whether any threading will produce plain weave across the fabric. Set up two lines, treadle 1 and treadle 2. Alternate the threads in the threading in the two treadles. For example, block A of “2:1 Beiderwand” from the drawdown above is: 1, 3, 4, 2, 3, 4. We alternate these six threads:

Treadle 1: 1, 4, 3

Treadle 2: 3, 2, 4

We don’t have to go past the first block to realize that weaving a tabby across the fabric is impossible as shafts 3 and 4 appear in both treadles. Those two shafts will stay up or down with every tabby pick preventing interlacement.

I have used this method for complex twills, for example. I was just lulled into a false sense of security that all tied unit weaves were following the rules.

Happy Weaving!

Marcy

Marcy Petrini 

February, 2025 

Earlier this month, I gave a presentation to the Westfield Weavers Guild on plain weave, setts, different size threads, and color interactions.

At the end of the talk, my friend Catherine Marchant asked a question about tabby, which has gotten me thinking about the different ways we use the word.

The fabric determines the structure, and a tabby cloth is a balanced plain weave: the same number of warp ends per inch and picks per inch, as shown in the sample below. For example, the sett may be 12 epi and the weft is 12 picks per inch.

What about 13 picks per inch, or 11? Is that still a tabby cloth? Let’s not get too technical, but we can all agree that the fabric below is not a tabby, it’s a weft dominant plain weave.

The treadling steps to achieve that plain weave, whether is tabby or plain weave, depend on the structure, but we tend to call tabbies the treadles which are attached to the shafts that will produce plain weave when used.

For example, if I am weaving a compounded fabric with a supplementary weft, for example overshot or summer and winter, I may say that I always put my tabbies on the right side of the treadles. However, these treadles will be different for these two structures.

For overshot, my tabby treadles are:

For summer and winter, my tabby treadles are:

As long as we know the structure, we know what we mean by tabbies, and we can attach the shafts to whatever treadles we find convenient to weave.

However, do these tabbies always produce a true tabby?

When I sample structures with a supplementary weft, I like to use 10/2 cotton for warp and ground weft. My sett for the warp, however, is not the 24 epi that I would use to make a tabby in a simple cloth (simple by Emory’s definition, one warp, one weft). I use 18 epi to allow room for the supplementary weft.

Within the compounded fabric, that ground cloth is, in fact, a tabby: a sett of 18 and 18 picks per inch for the ground weft, as shown in the summer and winter sample below.

A supplementary weft fabric means that the supplementary weft is not needed for the integrity of the cloth. If I were to cut out the supplementary weft that produces my motifs, I would be left with a tabby: 18 epi and 18 ppi – a rather loose fabric, but balanced.

Some weavers, however, prefer to sett the warp as they do for a true tabby. Thus for the 10/2 cotton, they would sett it at 24 epi. To give room to the supplementary weft, then they use a smaller ground weft, for example 20/2 cotton.

Now we have a ground cloth of 10/2 cotton sett at 24 epi and a ground weft of 20/2 cotton which presumably weaves at 24 ppi.

Is that tabby? It’s definitely plain weave!

We can ask the same question of rectangular float weaves (Emory classification) which are derived from plain weave: huck, huck lace, Bronson lace, spot Bronson, etc. For example, huck lace can have areas of plain weave as shown in the fabric below.

On four shafts, the tabbies for huck lace are those of plain weave 1 & 3 vs. 2 & 4, not surprisingly, since the structures is based on plain weave.

But is the plain weave area tabby? In the fabric above, it doesn’t look it. When I weave lacey weaves, I chose the warp sett depending on the effect I want: balancing lacey areas and plain weave, I may use the tabby sett; if I have lots of lacey areas and I am afraid that the fabric will be too sleazy, I may increase the sett; conversely, if I use huck which has lots of plain weave areas, I may decrease the sett to increase the drape for the lacey fabric.

So, are those plain weave areas tabby? They are plain weave!

In weaving, we always have grey areas…..it’s ok, just as long as we know what we are weaving, and we like the final result!

Happy Weaving!

Marcy