Designing Shadow Weave the Atwater System

Designing Shadow Weave – the Powell System

In 1976, Robin and Russ Handweavers published a book by Marian Powell (1000(+) Patterns in 4, 6, and 8 Harness Shadow Weave) which offered an alternative threading and tie-up for shadow weave. Powell’s approach was to thread the shadow weave unit pairs in sequential order, making it more twill-like in threading and treadling. It is sometimes said that this approach is easier to thread, but harder to understand for designing.

1. The Tie-Up

The Powell tie-up looks quite different from the Atwater tie-up, but it is quite distinctive and easy to identify in publications:

4 4 6 6 6 8 8 8 8 3 3 5 5 5 7 7 7 7 4 4 4 6 6 6 6 2 2 3 3 3 5 5 5 5 1 1 Four 2 2 2 harness 4 4 4 4 1 1 1 3 3 3 3 Six harness 2 2 2 2 1 1 1 1

Eight harness

2. Determining shadow “pairs”

Let’s review the unit concept again:

Each unit of a shadow weave pattern is formed by a pair of threads of contrasting characteristics (dark/light; thick/thin; bumpy/smooth; dull/shiny, etc). In most draft descriptions the “dark/light” terminology is used. A block unit, then, is a pair of threads, one dark and the other light. In shadow weave we consider the dark thread to be the “primary” and the light thread to be the “shadow” partner.

In the Powell threading, the partners are selected in sequential order, and they don’t change with the number of harnesses:

For 4 harnesses, the pairs are: 1 and 2, 3 and 4. For 6 harnesses, the pairs are: 1 and 2, 3 and 4, 5 and 6. For eight harnesses, the pairs are: 1 and 2, 3 and 4, 5 and 6, 7 and 8.

1 3. Determining Threading Units

Now that we have identified our pairs, we can work out our block units. Each pair can create two different pattern units – one if the threading is dark-light, and the other if the threading is light-dark. For example:

Four harnesses have two pairs of partners, but four pattern blocks: 1D/2L, 3D/4L, 2D/1L, 4D/3L.

For six harnesses, we have six pattern blocks: 1D/2L, 3D/4L, 5D/6L, 2D/1L, 4D/3L, 6D/5L.

For eight harnesses, eight pattern blocks: 1D/2L, 3D/4L, 5D/6L, 7D/8L, 2D/1L, 4D/3L, 6D/5L, 8D/7L.

4. Select a Profile Draft

Now we know how many blocks or units we have to work with. Next we can design a profile draft of the blocks we want to use.

Although we can still use twill threadings as profile drafts, we can’t convert them in the same way that we were able to do with the Atwater system. Instead of redrawing the twill threading with spaces in between for the “partners”, we need to do a true block substitution, replacing each block of the profile with its Powell threading block.

Let’s look at this threading for a simple twill pattern as if it were a profile draft. Each square, instead of representing one warp thread, represents one shadow weave unit – a pair of threads in a dark/light or light/dark sequence.

Block D – 4D/3L Block C – 2D/1L Block B – 3D/4L Block A – 1D/2L

4 4 4 4 3 3 3 3 2 2 2 2 1 1 1 1 D C B A D C B A

2 Let’s compare the two systems for this profile:

The Atwater layout The Powell layout

Can you see the threading units? Both are “as drawn in”, but the tie-up is quite different.

In the block development (multiple repeats of each block) you can see the units better:

Here’s the drawdown.

3 Treadling

If you examine the treadling sequence that results when a draft is treadled “as drawn in”, you will see that we are treadling on opposites. If we look at the threading pairs – 1 and 2 and 3 and 4 for four harnesses; 1 and 2, 3 and 4, 5 and 6, 7 and 8 for eight harnesses – you will note that, usng the Powell tieup, we are still treadling on opposite sets of harnesses for each block:

Other types of treadling are possible, but they will give different effects.

Working with Points and Reversals

The guidelines for the handling of patterns which ascend or descend to a point, and then reverse, are the same for the Powell threading as for the Atwater threading:

1. When you are “ascending” a twill line (going from low harness numbers to high harness numbers), the dark partner goes first. When you are descending, the light partner goes first. The descending line is a mirror image of the ascending line.

2. In order to keep the alternating dark/light color order constant, you need to either add or remove one thread at the reversal points.

Example: Using a simple profile sequence of 1-2-3-4-3-2-1:

Ascending: 1D/2L – 3D/4L – 2D/1L

Point: 4D OR 4D/3L/4D

Descending: 1L/2D – 4L/3D – 2L/1D

4 Here is what it looks like if you follow these rules for a twill-fashion development:

“Preferred” vs. “Secondary” Threading

As we saw with the Atwater examples, when threading with blocks it is sometimes possible to get a different and equally satisfactory effect by not following the guidelines for handling reversals. Powell refers to this in her book by offering examples of “preferred” (incidentals added or dropped at points, and light preceding dark on the downslope) and “secondary” (no changes at points and dark always preceding light) threadings.

On the next page we see a comparison of the two variations. With the “preferred” threading, there is a light outline all around the shape. With the “secondary” threading, it appears as if the light comes from one direction.

5 “Preferred” threading

“Secondary” threading

6 Summary

The Powell threading is used in the same way as the Atwater threading and may be varied in the same ways. Tie-ups are different (see separate handout for explanation of tie-ups). The Powell threading uses adjacent pairs of harnesses for its blocks, instead of opposite harnesses as the Atwater system does, and a block’s treadles are therefore also adjacent. It is more consistent as you add more blocks to the pattern. However, the tie-up is not intuitive and not easily remembered. This difficulty can be overcome by keeping a record of the three tie-ups which are Powell’s standards.

Bibliography:

Powell, Marian, 1000(+) Patterns in 4, 6, and 8 Harness Shadow Weave. Robin and Russ Handweavers: 1976, reprinted 2001.

Mimi Smith, “Atwater-Powell Shadow Weave”, Shuttle, Spindle, and Dyepot, Winter 2003-4

Strickler, Carol, Editor, A Weaver’s Book of 8-Shaft Patterns, Loveland, CO:Interweave Press, 1991.