How to Calculate and Adjust Loom Waste

For each of our weaving patterns, Gist designers provide you with a total warp length for the project, a number that includes the amount of loom waste. But you may have noticed that this number can vary between projects—for example, the One Warp Towel Set includes 25.5” for loom waste and fringe, while the Onwards and Upwards Towels include 20”. How do designers arrive at these numbers, and how can you calculate and adjust loom waste for a weaving project?

What is Loom Waste?

Waste is an unavoidable part of the weaving process—there are always a few inches lost at the front for your tie-on knots, and another few inches of unweaveable warp at the back. Depending on the pattern, there can also be loom waste in between projects on the same warp.

There are a few factors that affect how much loom waste you experience. First, new weavers tend to create a little more—while you’re getting the hang of warping, beaming, and tying on, you may tie longer knots or need larger margins than a more experienced weaver does.

The type of loom you use will also affect how much waste you experience. In my studio I have two looms with very different waste: a big old Scandinavian loom and a small table loom. I can get away with weaving teeny tiny warps on the table loom that would hardly make a shed on the big loom! More shafts also usually means more loom waste.

The Easiest Way to Calculate Loom Waste

To calculate for your loom, all you’ll need is tape measure, a piece of paper, and a pencil.

You will want to measure the length of your loom from the front breast beam to the back beam, following the same path that your warp will take. If your loom is very deep it might be easier to measure from the front to the reed then the reed to the back, and then add those together. This is your loom waste. Write this number down! Seriously—I have mine taped to the studio wall because I think I’ll remember and I never do.

This is a rough and somewhat inaccurate way to measure your loom waste, but you'll be more likely to end up with extra warp length than too little. If I use this rough calculation, I usually have 10 or so inches of warp that I can still weave at the end of a project. I don’t waste this length of warp, but use it to sample or empty bobbins and I save the fabric for sewing together later on.

Another Way to Calculate Loom Waste

Once you’ve made a few projects on your loom and gained some confidence, you might like to make more accurate loom waste calculations that suit you and your equipment. This is easy to do too!

  1. After you’ve finished weaving your next project, save all of the pieces of waste from the front and back of the loom.
  2. Unknot your tie-on from the apron rod and measure the pieces. I can see that I waste approximately 4-6” with each knot. Record this number on a piece of paper.
  3. Measure the waste attached to your back apron rod. Divide this number in half, because each piece of waste wraps around the back beam (unless you tie on in the back—in which case you’ll have to untie that knot too!). I had a few waste pieces in my scrap bag, so I calculated an average of 14” of waste for my big loom and 9” for the small loom.
  4. Add your front and back waste numbers together and save them: I approximate that I need to add 21” for my big loom, and about 13” for the table loom.

When I calculate this way, I still usually round up while warping just to give myself a little extra space.

Applying your Custom Loom Waste to Patterns

You may have noticed the text “adjust as needed” next to warp length calculations on Gist patterns. How do you apply your custom loom waste measurements to a given project?

For this example, I’m going to use the Ripple Pillows. The first number you need is the woven length—this number tells you how many inches you are weaving on the loom. For the Ripple Pillows, the woven length is 46”. 

The warp length tells us that the designer has given us 2.1yds or 76” to weave two pillow fronts with 30” of loom waste. It’s easy to calculate that 30” of loom waste + 46” of weaving length = 76”—so if you need to adjust the waste for your loom, add your custom loom waste measurements to the woven length of a project.

Other Factors to Keep in Mind About Loom Waste

Beyond how much you use to tie knots and how deep your loom is, there are a few other things that may affect your loom waste.

One thing I’ve been lazy about calculating in the past is my take-up—I’ve read that you should add an extra 10% to your project’s weaving length to account for this. My laziness has caught me short a few times when the take-up was more than expected!

The warp doesn’t travel in a straight line like a ruler—as it goes under and over your weft, a little bit of length is added each time. This small amount can add up to a lot over an entire warp, and how much you need changes depending on the project. A warp faced project like the Viken Trivets, for example, has a lot more take-up than a plain weave project like the Equinox Napkins. When you start to adjust weaving patterns to suit your needs, don’t forget to add take-up to your total warp length so that you don’t find yourself short!

Loom waste can also be affected by how long your apron is or how close your tie-on bar can get to your heddles. Some designers include fringe separately as part of their calculations, while others utilize their loom waste to create fringe, so read the instructions carefully.

What to Do with Loom Waste

Loom waste is called thrums—but what can you do with them? If you weave with natural fibers, you can compost them or take them to your local textile recycling facility. If they’re nice and long, you can use them to weave with, either as new weft or to weave headers or waste sections. I’ve used my longest pieces of loom waste to weave bands on my little band heddle too.

Strong warp threads can be used to tie tomatoes in the garden and unbleached fibers can be used to tie up herbs for cooking. You could also make small tassels or use Ode thrums to knit thrummed mittens.

This spring, I took some pieces of loom waste and left them around the garden—and then had fun watching the robins and sparrows collecting them for their nests!

About Amanda Rataj

Amanda Rataj is an artist and weaver living and working in Hamilton, Ontario. She studied at the Ontario College of Art and Design University and has developed her contemporary craft practice through research-based projects, artist residencies, professional exhibitions, and lectures. Subscribe to her studio newsletter or follow her on Instagram to learn about new weaving patterns, exhibitions, projects, and more.

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