Weaving Preparation: Wool yarn testing.

One of the things in frantic preparation right now are the experiments for the Textile Forum this year. We'll be having a rather experiment-heavy Forum, and all three planned things involve dyeing - one of the experiments will be a repeat of the Pompeii dyeing experiment exploring the influence of kettle metals, one will be a test about linen mordants with protein, and one will be looking at dye penetration in woven fabrics of different densities.

The lattermost requires appropriate yarns, and I will get to spinning tonight - a few hundred metres of yarn need to be done for weaving several samples. The weaving will take place at the Forum, and since the weaver lives in the Netherlands and I live in Germany, she will only see the yarns right before having to use them.

Most modern weavers use machine-spun, plied yarns, at least for the warp, because they are (usually) stronger than singles. Of course a plied yarn is stronger than just one of its singles, and modern yarns are often soft-spun, which means they are not very strong. So modern weavers tend to be a little nervous about using singles in the warp.

Just to make sure that the yarn is suitable for weaving - as in "strong enough" - I was sent instructions for testing, taken from "Inventive Weaving on a Little Loom: Discover the Full Potential of the Rigid-Heddle Loom, for Beginners and Beyond by Syne Mitchell (Storey Publishing 2015)". The two tests are the snap test and the drift test. For the snap test, you take the yarn between your hands so that about 10 cm are slack and then "snap your hands apart sharply"; for the drift test, you apply even, slow tension.

The instructions in the book say that if the yarn survives the snap test and "stretches and then stops" in the drift test, it's suitable as warp yarn. Can you guess my problem?

"Sharply" is not a very quantifyable thing. So if I take my yarn and pull my hands apart sharply, it will break. The same is true if I take a four-ply Regia sock wool yarn. In the drift test, my yarn will stretch and stretch and stretch and eventually snap... so according to these instructions, it would not be suitable for weaving.

I think the problem here is that you'd need to be a weaver and know the amounts of tension or snappiness in your own weaving process to really make these tests helpful. For non-weavers like me? Or for "remote testing" yarns? It needs to be more quantifyable.

So here's my equivalent to the drift test: Tie an empty plastic water bottle in the middle of a piece of the yarn to be tested, then tie the two ends somewhere so that the bottle hangs in a suitable way to be filled. (Hint: A shower or bathtub, or someplace outside that can take a splash of water would be good places.)

[caption id="attachment_2677" align="alignnone" width="319"] Setup for the drift test. Please do admire the typical "bathroom-in-Germany-in-the-Seventies" tiling in the background. The white spots on the handgrip also tell you that we have really hard water here.


Measure out a certain amount of water, such as one litre, which will be one kilogram. Then, slowly and with as evenly a stream as possible, pour water into your bottle until the yarn snaps. The difference between the amount of water you filled into your pouring container and the amount still left is the weight the yarn could take - in my case, about 880 g.

Now the equivalent to the snap test: Tie a weight to one end of your yarn to be tested, then measure out one metre of yarn plus a bit to hold, starting above the weight. Take the end of the yarn securely in one hand, the weight in the other, hold them side by side high enough, then drop the weight. If the yarn bounces back, it has survived the test. If you are not sure on how much weight is necessary for the thread to pass the weaver's requirements, add more weight until it snaps. (Obviously, the smaller the increments of added weights are, the smaller your squishiness factor will be. My yarn snaps somewhere between about 60 and 100 g of weight.)