After a short break, I'm picking up this email series on liftplans to talk about… tie-ups. Yes, you heard me correctly. But why start with a liftplan, if what we want is a tie-up? 

Well, the crucial thing about liftplans is that they are a direct record of the shafts we need to lift. They enable us to pin down what combinations of shafts we will need to make, without being distracted by how we are going to make them. The what and the how are two different considerations. Although each necessarily informs the other, it is worth keeping the distinction in mind.

By the way, if you're new to this series and want to catch up, links to previous episodes are at the bottom of the page.

When I talked about turning a liftplan into a tie-up in Part 4 of this series, I pointed out that it is by no means certain that any given liftplan can be converted to suit a fixed a number of treadles. The design may simply require too many distinct combinations of shafts. In some of these cases, however, we can find a solution in the form of a skeleton tie-up.

The basis of this approach is the insight that several of the required combinations of shafts have something in common. If we can identify and isolate those common components, we can assign them to individual treadles. Each treadle on its own only lifts some of the shafts needed, but when we weave we can mix and match them to make the complete lift required. 

It’s an approach that requires flexible thinking in order to plan it, and flexible two-footed treadling in order to execute it! However, I believe it is worth the effort for the flexibility in design that it gives the weaver. And I should add that the principle can be made to work on any loom. I am going to start with an example for a jack loom, but next week will show how it can be adapted for a countermarche loom.

At the moment in my Understand Double Weave course, students are getting to grips with a skeleton tie-up for double weave blocks on 8 shafts. It’s right at the forefront of my mind, so that’s the example I am going to use. If you’ve not come across double weave blocks before, you might want to check out my introduction on Warp Space.

The first things we are likely to want to do with double weave blocks on 8 shafts is to make patterns which depend on exchanging layers and blocks, such as window panes and checkerboards.

The draft I have created for this example shows a pattern of connected squares. We can see the result more clearly through the magic of the ‘double weave’ view:

In the top half of the design the squares are pink on a grey ground, and in the second they are grey on a pink ground. The liftplan looks quite complex, but if we were to apply the whittling-down process I described here, we would find it is made up of just 16 distinct combinations of shafts: four groups of four. 

One group of four lifts places the grey layer above the pink layer all the way across the cloth…

…while another group places the pink layer above the grey layer. 

A third group of lifts places pink on top in one block and grey on top in the other; and these are switched around by the fourth group of lifts. 

Taken altogether, this is the what of our design, i.e. the shaft combinations we need to turn into a tie-up:

One of the fascinating things about double weave is that we can break the weaving down into two distinct tasks. One component is the interlacement of warp and weft which, as we would expect, creates the structure of the cloth. The other component boils down to ‘moving stuff out of the way’. It is this second component which allows us to control which layer we see on the face of the cloth.

Within all four liftplan segments shown above, the interlacement remains consistent: we are weaving two layers of cloth and we need to make plain weave alternately in each layer. On the threading shown here, that means lifting 1 and 3 opposite 2 and 4 for one layer, and 5 and 7 opposite 6 and 8 for the other layer (remember that each column in a liftplan represents a shaft).

These four lifts will be the backbone of our skeleton. I am going to place them in the centre of the tie-up. 

I have placed odds on the left and evens on the right for each pair, which simply reflects my personal preference. What is crucial, though, is that I have placed the treadles for shafts 1 to 4 on one side and those for shafts 5 to 8 on the other.

If we now remove this component from our liftplan we can see the other bones that we need. 

These are the lifts that do the work of keeping the layer we want on the face of the cloth. We can see that they come in two varieties, either raising the whole of a layer (shafts 1 - 4 or shafts 5 - 8) or just one block at a time (shafts 1 & 2, shafts 3 & 4 etc).

We can separate these moving-out-of-the-way bones into those which act on shafts 1 to 4 and those which act on shafts 5 to 8, and assign them to the left or right side of our tie-up accordingly. 

Now we have a 10-treadle tie-up with five treadles operating each layer of our double cloth, and each set of five is assigned to one foot. In my example, the left foot will control the layer on shafts 1 to 4, while the right foot controls the layer on shafts 5 to 8.

When I want to see the grey layer on the face of the cloth. I would treadle like this:

I weave the two layers alternately, using the left foot to open the shed for the pink layer and the right foot to open the shed for the grey layer. Whenever I weave the pink layer, however, I also use my right foot to raise the grey layer up out of the way, keeping it on the face of the cloth.

When I want to see the pink layer on top, I need to raise it out of the way whenever I am weaving the grey layer.

When I want to see a different layer in each block, I will need to use both feet on every pick: keeping the pink layer on top in one block when I weave the grey layer, and keeping the grey layer on top in the other block when I weave the pink layer. 

Now we have the how as well as the what to accomplish this design.

And, having done the thinking work thoroughly, we have created a tie-up that we can use flexibly to create many other double weave designs as well.

This tie-up is easily adapted for a sinking shed loom, as the only change you need to make is in the definition. The treadling which puts the grey layer on top here will yield the pink layer on top instead, and so on. However, on a countermarche loom we have an additional challenge, since we need to account for more shafts.

I'll cover this next time.