Needles, thread, and going over thick seams
Okay. Last lesson we talked about why denim is forgiving and how to cut it down. Today we're talking about the part that actually scares people off denim, which is sewing through the thick spots. The waistband seam, the hem where it folds over itself four layers deep, the flat-felled seam on the inseam. That's where machines jam, needles snap, and people decide denim's not for them.
Here's the thing. It's not the denim that's the problem. It's the wrong needle and going in too fast.
The needle you actually need
Regular sharps or universal needles will get through a single layer of denim fine, but the second you hit a thick seam, they start deflecting instead of piercing. You'll hear it before you see it, a kind of thunk instead of a clean stitch, and then either the needle bends or it snaps outright.
Buy denim needles. They're labeled right on the package, size 90/14 or 100/16 depending on how heavy your denim is. The point is stronger and the shaft is thicker so it doesn't flex when it hits something dense. This is not me being precious about gear. It's the single easiest fix for the exact problem you're about to run into today.
And yeah, I already told you a few lessons back to change your needle more than you think you need to. This is where that habit pays off. A needle that's been through a few projects of regular cotton is not the needle you want meeting a four-layer denim hem for the first time. Put a fresh one in before you start.
Setting up for the thick spot
Before you sew, look at the seam you're about to cross and actually count the layers. A flat-felled seam, a folded hem, a belt loop overlap, some of these are five or six layers of denim stacked on top of each other. Your foot has to climb that like a little ramp and it's going to want to tip forward or backward instead of staying flat.
A few things that help:
- Slow down. This is not a fast seam. Go slower than feels necessary, especially in the two inches right before and after the thick spot.
- Use a hump jumper, or fold a scrap of denim as a shim. You put it behind the presser foot, level with the thick seam, so the foot stays flat instead of tipping. If you don't have one of the little plastic tools, a folded scrap works fine. I'm not going to pretend you need to buy a gadget for this.
- Hand-crank the needle through the worst of it. Turn the handwheel toward you by hand for the actual moment the needle crosses the thick part. You have way more control than the foot pedal gives you, and you'll feel resistance before it becomes a broken needle.
- Don't force the fabric through. If it's not moving, stop and check what's stuck instead of pushing harder. The machine's telling you something.
Backstitching, and where I'm contrarian
At the start and end of most seams on an upcycled piece, people backstitch like they're building a bridge. I don't think you need it, not for casual seams. A couple forward stitches over your starting stitches and a decent knot holds fine for a bag lining or a patch pocket. Save the real backstitching, the kind you go back and forth over twice, for stress points. Belt loops. Waistband corners. Anywhere the seam's going to get pulled on hard and repeatedly. Everywhere else, close enough isn't a setting, but it also doesn't need to be a fortress.
A story on the topic of not being distracted
I want to tell you about the cookies, because it's relevant, I promise.
I taught a class once and brought cookies I'd made the night before, and they came out flat as coasters. Like hockey pucks you could stack. Turns out I'd been cutting a stack of old jeans into pieces at the same time I was baking and I completely forgot the elevation adjustment, less flour, more liquid, the usual up here. My head was on denim, not batter.
I brought them anyway and told the class exactly what I did wrong. Same thing applies at the machine. The moment you're distracted, thinking about dinner or the game or whatever, is the moment you feed a thick seam through too fast and snap a needle or scar the fabric. Denim forgives a lot. It does not forgive you not paying attention for the four seconds it takes to cross a thick spot.
What to actually do at home
Grab a scrap of old jeans, fold it over on itself three or four times to fake a thick seam, and practice crossing it. Do it with the pedal first, feel what happens when you rush it. Then do it hand-cranked, slow, using a shim behind the foot. You'll feel the difference immediately and that's the whole lesson, really, in your hands instead of my mouth.
Before next time: bring in whatever old jeans or denim you're planning to upcycle, and find the thickest seam on them. That's what we're cutting into next.