What's the Right PPI?
Madelyn is temporarily out of the office—or, more accurately, the studio—so for the next couple of weeks, we'll have guest weaving teachers answering the questions they hear most from their students. Today's Ask Madelyn is from Robyn Spady, frequent Handwoven contributor, workshop host, and weaving blogger extraordinaire.
How do I determine the correct picks per inch for my project?
After my first web seminar, I was surprised how many people asked: “How do you get the right picks per inch?” My response was, “It depends on what you are weaving.” Not the quintessential answer many were looking for, but an honest answer, in my opinion.
Picks per inch (ppi) is one of a number of things I continually work on mastering. I would also include even selvedges and warp tension on that list. The right ppi simply comes down to what is required to obtain the desired results.
The majority of what I weave is yardage, dish towels, and samples. These fabrics I weave “square.” In other words, I weave the same number of picks per inch as the ends per inch (epi) in the warp. But I’ll be completely honest: I don’t always get it perfectly square. I strive for two things: 1) the appropriate ppi for the project and 2) consistency. After I achieve the appropriate ppi, I will periodically count my ppi to verify that I’m producing consistent results. I check my ppi about every hour or so, more often if necessary. This means both consistency in beat and frequently advancing the warp so that the beater always strikes the fell in about the same spot. If I notice my ppi changing, I’ll try to figure out why and make the necessary adjustments.
When beginning a project, if I’m not achieving the ppi that I need for good cloth, I first consider resleying my warp. If my ppi is too high, I will increase my sett. If my ppi is too low, I will open up my sett. These changes in sett may only be an end or two per inch, but it can result in a significant difference. I believe weavers have a natural beat. When we start changing our technique, we are prone to becoming inconsistent. If a weaver tries to beat more firmly or more lightly than their natural beat, it’s very likely to result in inconsistency in ppi.
Our looms are another complicating factor. Maintaining a consistent ppi has to do with more than just beat and advancing warps. The weight of the beater, the geometry of the shed, and other factors all have their effect. For example, if I’m weaving 5/2 cotton as a 2/2 twill (as you would in weaving a tartan fabric), I will sett this at 16 epi on my counterbalance loom to weave it square; however, if I weave this same yarn in the same structure on a different loom, I may need to sett it differently to weave it square. On another loom in my studio, 5/2 cotton woven in a 2/2 twill needs to be sett at 20 epi. It all comes down to physics.
Especially if you're weaving with fine threads, it helps to nave a magnifying lens handy when you weave. The holidays are coming. Perhaps a pick counter (sometimes called a linen tester) is something you need to consider gifting to yourself . Prepare to count your ppi and count it on a regular basis. Consistency in technique comes with practice.