Designing a Twill Gamp: Part 1

A twill gamp is one of the most useful samplers in a weaver’s repertoire. It is not only a fantastic reference to have in your library of samples, but the process of creating it can also be an invaluable experience, whether you work through a published project or design your own.

For this series I am going to work through the process of designing a twill gamp. I’m going to assume that you have a loom with (at least) four shafts and that you know what a twill is. We will fill in the rest as we go.

Defining a Twill Gamp

The essence of a twill gamp is that it is made up of (usually) squares of different twill interlacements. This is achieved by varying both the threading and the treadling.

The warp is made up of sections threaded with different sequences, e.g. straight draw, point draw, and so on, and then the cloth is woven using the corresponding sequences in the weft. This produces both the classic interlacements – the zig-zag pattering of a point twill, for instance – and more unusual interlacements – such as when an advancing point treadling meets a herringbone threading.

Other variations can be added on top of this, such as variation in the size of the sections, their colour and so on, but the weave structure is the primary focus.

Part 1: Constraints

What is a constraint? The dictionary typically defines a constraint as “something that limits or restricts what you can do”. This sounds quite alarming, but many creative people deliberately use constraints in one or more aspects of their practice. It can help them to narrow their focus rather than scatter their energy on a bit of this, a bit of that.

As weavers we generally have one immovable constraint: our loom. It is what it is, whether ‘it’ is a table loom rescued from a skip or a brand new countermarche loom, fresh from the manufacturer and still smelling of varnish and packaging. Whatever we design, it has to be compatible with our loom – or we have to be willing to put the work in to modify our loom, which is an avenue I am not going to go down right now!

Therefore, when we plan a project, the first thing we need to take into account is: what can I accomplish on my loom?

Shafts & Treadles

The beauty of twills is that you only need four shafts to unlock a fantastic variety of designs, so in that respect I don’t really consider shafts much of a constraint on this project. However, you could well apply the same principles to designing a twill gamp on eight or more shafts, so feel free to do that if your loom has the capacity.

A greater constraint exists if you have a floor loom with treadles rather than a table loom or dobby. This is something I discussed previously, and we will revisit it in the context of this project later on when we talking about liftplans and tie-ups. There are plenty of options open to us, so at this stage we can just acknowledge the treadles – hi, treadles! – and move on.

Weaving Width

The weaving width of the loom is the constraint we really need to address before we can start. Yes, it is possible to weave double width, but that is a project in itself and not something to shoehorn in here. So let’s take weaving width as a fixed limit on our gamp and see what that means in practice.

A narrow loom

The workshop looms I use in the Weaving Space have a weaving width of 40 cm, or just under 16 inches, which is not especially large. The most I could comfortably get out of it would probably be 14 or 15 inches in the reed. What does this mean for my gamp design?

When I am planning the size and scale of a project, I always reach for the squared paper. I can draw a simple diagram of the piece I am planning and see how the proportions look when visualised to scale.

Here I have marked off one square for each of my nominal 16 inches and sketched out some possible arrangements for a gamp. In this example I am sticking to sections of equal width, though of course that is not an essential: you might want to sketch some alternative ideas.

If I opt for as wide a piece as I can make, say 15”, then I could divide those 15 inches into three sections of 5”, five sections of 3”, six sections of 2.5” … and so on.

A narrower piece of 12” offers me a different range of options: three sections of 4”, four of 3”, six of 2” … and so on.

Each possibility prompts me to ask more questions of myself, which helps me to refine my ideas about the project and what I want it to achieve.

Refining the plan

Reviewing the diagrams above I am immediately presented with two more factors I need to consider.

First of all, how do I plan to mark out the sections of my gamp, or do I need to mark them out at all? If I want to ‘frame’ each square with a contrasting outline, as I did in the piece shown above, then that will take up some of my available weaving width. I can either add extra ends and increase the overall width, or I can maintain the overall width of the piece, and take a few ends away from each section.

In my examples above, I really can’t add any more to the 15” plan, so to add an outline I would need to reduce the individual sections. However, the 12” plan is well within the capacity of my loom, so I can maintain the section width by adding extra warp ends.

Secondly, the scale of the design is inextrictably linked with my choice of yarn.


Our yarn is not a constraint in the same way that the loom is – fixed and unalterable – but it does place limits on us. If there is a particular yarn we want to work with, then we need to take its characteristics into account. If we plan to buy a yarn to suit the project, then we need to be able to specify the kind of yarn we want.

Yarn from the stash

If you have a lot of a yarn that you know and love, that’s great. You have a head start on designing your gamp! You may already know what sort of a sett this yarn requires for a twill; if not, that is the first thing you need to establish. I wrote about this for Craftsy and you can still find the post here.

Once you have an idea of the likely sett for your yarn, you will be able to get a sense of the scale of the twill. If your yarn needs to be set at 16 epi, a three inch section of warp will contain 48 ends. If your yarn needs to be set at 36 epi, a three inch section of warp will contain 108 ends. In the second case, a narrower section of only two inches will still give you a lot of pattern; whereas in the first case your three inch section may only yield three or four repeats of a longer threading, so you really don’t want to cut it down further.


If you plan to go shopping for yarn for your gamp, then you need to apply the reasoning above in reverse: what scale do you want to achieve in your gamp and in the individual twills? Do you want a few big squares or several smaller ones? Do you want a very finely detailed pattern, or a bold, chunky one?

My recommendation

I don’t want to over-prescribe this project: my intention is to help you think through what you want to achieve and enable you to achieve it. However, I will make one recommendation, which I will return to next time as we consider developing the threading design in more detail. Here it is:

Don’t design for less than 36 ends per twill, and aim for 48 or more if you can. Fewer ends than this will reduce the visual distinctiveness of each interlacement, which is the chief purpose of this kind of project.

Of course, if you are working with a finer yarn as described above, you will want more than 36 ends to get a reasonable sample of each twill. But unless you are working with a really thick yarn – needing 10 epi or less – then I recommend reducing the number of sections to meet the 36-end minimum rather than the other way around.

To sum up

The most important constraint on your design is the weaving width of your loom. If you have a narrow loom, this is a particular challenge, but for any loom you still need to weigh up the size of your individual threading sections versus the number of sections you want to include and whether or not you want to include a contrasting woven outline.

The scale of the design is also dependent on the yarn that you choose: a finer yarn will give you more pattern detail on a smaller scale than a thicker one.

If you want to work along with this series, it’s time to fetch out the squared paper and start thinking through your options! In my next post I’ll look at developing the detail of the threading plan.

First posted on © Cally Booker

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