The lampas is off the loom and finished. As you can see it bloomed up nicely with the doubled threads. I made a few mistakes in the patterning, but I am very happy with the piece overall.
Monthly Archives: June 2013
First up, a tunic for the hubby:
Several people have asked how to calculate how much yarn is needed for a weaving project. I’ve decided it makes more sense to write up a post here I can refer people to as needed.
- Plan your project
The first step, as with most projects, is deciding what you want to make. You will need to know the length and width of the fabric you want to weave.
Let’s say you want to weave an aprondress – mine needed 6 yards of fabric at 20″ wide.
- Determine your sett
Sett – the number of warp threads per inch
The thickness of the warp thread and the weave structure you intend to use controls how closely together each warp thread is spaced. There are several ways of calculating this, but Handwoven Magazine has a wonderful chart for a large selection of threads. I tend to just refer to this. Again, if you are very particular about the hand of the fabric, I recommend sampling at a few different setts.
- Determine take up and shrinkage
Take-up – the amount of draw in as the threads move over and under each other.
Shrinkage – the amount the fabric shrinks during finishing (such as running it through the washer/dryer).
Decide how important this measurement is. For a tea towel, you may not care if the finished project is a little larger or smaller. For fabric for a garment, you might be more concerned. Why does this matter? If you aren’t overly concerned, you can use the standard take up and shrinkage estimate of 15%. If the finished size is important – the only thing to do is sample your cloth. For sampling, it is suggested to use a minimum of a 10″ by 10″ square. Measure this while on the loom, once off the loom, and again after finishing the fabric.
Here is a sample chart:
Width Length On the loom 10″ 12″ Off the loom 8.7″ 10.9″ Take-up 15% 10% After finishing 7.5″ 9.6″ Shrinkage 15% 13%
This gives us 33.33% take up and shrinkage in width, and 25% shrinkage in length.
- Determine the number of warp threads
If I want finished fabric of a certain width, I need to weave a wider fabric so it will shrink to the desired finished size. We take our desired width and add the additional width needed to account for shrinkage. This gives us the ‘width in loom’ of our fabric. We then multiply this measurement (in inches) by the sett (threads per inch) to get the total number of warp threads required.
If I want a fabric 20 inches wide with a 33.33% take-up/shrinkage I need to set up the loom to weave fabric 26.66 inches wide. The heavy wool I used had a sett of 15 epi (ends per inch). Therefore, I require 400 warp threads.
- Determine the length of each warp end
Now that we know how many warp threads are needed, we need to determine how long each one needs to be. We take our desired length, and add additional length to account for take up and shrinkage. We then add any desired fringe length. And then, to account for the length of warp that is left on the loom, we add the loom waste (the standard is 27-36″, but it varies by loom).
So if I want 6 yards of fabric I add 25% take-up/shrinkage, which gives me 7.5 yards. I don’t want any fringe, so I add another yard for loom waste (it’s a big loom) – giving me 8.5 yards total.
- Calculate the total warp required
After the last two steps, this calculation is easy – we simply multiply the number of threads by the length of each thread.
If I need 400 threads 8.5 yards long, then I need 3400 yards in total.
- Calculate the total weft required
You will need to know your ppi (picks per inch), which you can get by sampling. For a balanced weave with the same thread, your ppi should match your epi. We then need to calculate how much weft thread we need. We multiply the width of the fabric on the loom by the number of picks we need to weave an inch of fabric – then we multiply that by the total number of inches of fabric on the loom we need.
If my width on the loom is 26 inches, and I have a ppi of 15 (to match my epi), then it takes 390 inches of weft. For 7.5 yards (270 inches), we will need 105300 inches – which is 2925 yards of weft.
And that’s it. We now have all the calculations we need to complete our project.