Picks Per Inch: A Beginner’s Guide
There’s a lot to learn when you first start to weave. One of the first things you will notice is that weavers have their own language. We start taking about reeds and sheds and warps and wefts, fell lines, epi, ppi and before you know it, the non-initiated have glazed over and all they hear is blah, blah, blah. As a retail worker and a lover of weaving, I’ve learned to explain new terms as I used them and quit talking when the glaze appears!
As a weaving instructor, there are a few things that I harp on (just ask my students!) and one of them is ppi.
PPI? Please speak English! Ppi refers to Picks Per Inch. Still doesn’t make sense? No worries, by the end of this post you will know everything you need to know and sound like a pro too!
First, a pick is one weft thread. So every time the shuttle goes through the weave, it is called a pick. When you count how many ends are in one inch, you get the picks per inch (ppi). Pretty simple. But why does this even matter?
Inkle weaving…no weft visible
Picks per inch plays a role in the structure of the finished fabric.
Picks per inch plays a role in the structure of the finished fabric. Lots of picks per inch in relation to the ends per inch (how many warp ends are in one inch) will give a weft-faced fabric. This means you will see the weft but not the warp. (Think Krokbragd.) Fewer picks per inch in relation to ends per inch means that you will have a warp-faced fabric. This means you will see the warp much more than the weft. (Think inkle weaving.)
If you are following a pattern, think of ppi in the same way as gauge in knitting. When you have too many picks per inch, you will run out of material and the project will be much shorter and denser. If you have too few picks per inch the fabric will be gauzy and may not hold together well. (Sleazy is the actual technical term!)
Balanced Weave
Since I am focused on beginners, I’m going to stick to a balanced weave. A balanced weave means that you have the same number of picks per inch as you have ends per inch. Your ends per inch is determined by your reed. If you are using a 7.5 dent reed, your ends per inch is 7.5, so for a balanced weave, you should have about 7.5 picks per inch. This works when you are using similar weights for warp end weft and I will be assuming this for the remainder of this post.
I’m using my 10 dent reed and have about 10ppi
Measuring Picks Per Inch
There are several tools that are designed to help you measure wraps per inch (wpi) another term we’ll talk about another time. These tools also work well for measuring your ppi. Personally, I prefer my tape measure.
As a beginner, you should be checking your ppi frequently. Every few inches, when you wind forward and when you come back to your loom. As you become more experienced, your eye will recognize when your picks per inch is off, but you should should still measure at the beginning of a project to be sure you are starting off right.
Let me share a true story here. As a teacher, I learn things every class I teach (I might learn more than my students). Anyway, I was teaching and all was going well with the pattern and weaving (okay, there was 1 disaster but I’ll save that for another blog) and it was time for the students to go home and finish their project. Later that week I received a call from a student looking for more weft yarn as she had run out. As always, when something goes wrong with a pattern, I panicked and wondered if I had made a mistake. But since I had woven this several times and had leftovers, and other students also had leftovers, I began to breathe again. I asked if she had checked her picks per inch. She had not. And so I learned to stress this many times in every class! There was a happy resolution though, we were able to find more yarn, though of a slightly different dye lot, and the scarf got finished and we are still friends! (Because weavers truly are the nicest people!)
Adjusting Picks Per Inch
On the loom and after washing!
Ok, so now let’s pretend you are weaving using a 7.5 dent reed. You’ve measured your picks per inch and they are at 14…now what??? (Most new weavers have way too many picks per inch, not too few.)
First, how you press with your reed matters! One gentle press is all that is needed. Some people refer to the pressing as allowing the weft to gently “kiss” the previous weft pick. You want spaces in your weave. Nice neat squares of empty space is perfect! When the project is no longer under tension, and has been washed, those holes will fill in. But they need the space! If they don’t have the space, you will have a very dense stiff fabric with little to no drape and the loveliness of the fibre will be lost.
Second, adjust your tension. If your tension is loose, the weft can pack in tighter. So a tighter warp means that the weft will pack in less tightly.
It takes practise to get consistent ppi, but it will become second nature and your eye will learn to recognize when you are even a quarter inch off!
PS - Did you notice that every ppi picture was a different project? That’s because I measure (and take pictures) of the ppi in every project!
