Learn how to choose sewing machine needles to sew denim, as well as thread and sewing techniques for success.
Hey y’all, it’s jeans sewalong week! All week I will be sharing tips and tutorials to get you sewing your own jeans. First up for me are tips to sew denim, including choosing the right denim needle and thread.
Denim is one of those fabrics people avoid because it’s thick, which means that when you have layers of fabric it just gets thicker. But if you handle it correctly, sewing your own jeans is not that hard. Really. I promise – I sewed mine in an afternoon. And if you just want tips on sewing thick fabrics in general but not denim specifically, check out this post.
For the TLDR version, check the list below. And for more reasoning behind these denim sewing tips, keep reading.
Top Tips to Sew Denim
- Cut with sharp scissors
- Use the right needle
- Use the right thread
- Use a bumper or a leveling foot (J foot)
- Go slow
- Use a mallet
Really that’s all there is to it. But let’s delve into each a little more in depth.
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Really, this one is kind of obvious. This is my favorite pair of dressmaking shears (affiliate link). I’m not sure when, in sewing, you’d want dull scissors. Sharp scissors are particularly important for thick fabrics, which, by virtue of their thickness can be harder to cut. Also stretch denim has polyester in it, which can dull scissors. And to keep my good scissors sharp, I visit a knife sharpener every so often for a tune up. I’ve had these scissors for decades and they’re still going strong. Note that newer versions might have enameled handles, but the blades are the same.
Use the correct needle
I have another in depth post about different types of needles, and in that post I mention that I use the same type and size of needle for 80% of my projects. Denim projects are in the 20% of projects where I will change to a different needle size and a new needle.
There are jeans needles that you can buy especially for sewing jeans. If you don’t want to buy specialty needles, just make sure to have at least a size 90/14 universal needle (100/16 for thicker denim). Needles should be matched to the thickness of the fabric you’re sewing. Denim is at least a size 90/14 or 100/16, while something like silk charmeuse would be a 70/11 and a medium weight linen would be an 80/12.
Remember that Europeans and Americans size their needles differently, which is why you’ll see two numbers on sewing needles. The larger number, the bigger the needle for both systems. European needle sizes refer to millimeter measurements, in that a 100 needle is 1 mm in diameter. So if you see a 100/16 needle, the 100 is the European size and the 16 is the American size.
Also note that a universal needle splits the difference between a ball point needle (for knits) and a sharp point needle (for wovens). Because most modern denim for garments has some spandex for stretch in it, a universal needle should be ideal. But if you’re having trouble with non stretch denim it might be worth switching to a sharp needle, and if you’re working with very stretch denim you might have better luck with a stretch needle. Always do some sample sewing on fabric scraps from your project to find the best needle type for your purpose.
One more note on needles for denim – you may want to have use twin needles for the parallel rows of topstitching that jeans often feature. I mostly use a twin needle for knit fabrics, but for use with denim you’d want a universal twin needle, not a ballpoint needle.
Use the right thread
For the regular seams, I use all purpose thread, just like I do for the vast majority of my sewing. This article goes more in depth about thread types and weights.
For the topstitching that comes with flat felling (a common seam technique for jeans; check this post for a tutorial), I switch to Heavy Duty all purpose polyester thread. Note that this thicker thread is also something that requires a bigger needle.
Tip: some sewing machines (my vintage one) hate the cotton thread that is marketed as jeans topstitching thread. My machine shreds this stuff and I spend all my time using it trying to get pretty topstitching but instead dealing with thread breakage.
If your machine is doing this, first try switching to a bigger needle, which will have a bigger eye. But if you do that and still see the thread balling up on the scarf (the part of the needle above the eye) and then breaking, switch to a thread made from polyester. Upholstery thread can also be a great substitute – it looks thicker like the topstitching thread you’re used to seeing on jeans, but it’s smoother than the cotton jeans thread, and so it is less prone to making your machine anger and shred it.
Use a bumper or a leveling foot
I don’t actually even know that this is what it’s properly called, this is just what I call it. Basically a bumper is a scrap of denim you keep near your machine while sewing. When you’re sewing over thick areas, like the place where the two seams cross at the back yoke, your machine might want to stall because of the presser foot being unbalanced. Bumper to the rescue! Fold it up, place it behind or in front of the presser foot to level the foot out and allow you to continue sewing.
If you have a newer machine, it might have come with a J foot, also known as a leveling foot (affiliate link). The video below shows how to use that, and if you can’t watch it below you can also watch it on YouTube here.
This, like sharp scissors, is kind of an obvious one. There are lots of places on the jeans where you might even want to handcrank the flywheel to get through. And that’s perfectly fine – it’s easier to slow down and do it right than to have to pull out the seam ripper and take out stitches.
Use a mallet
This is an unconventional sewing tool, but a mallet is handy to hammer down thick seams before putting them through the sewing machine. This will flatten the seam a bit, but it also breaks down the fibres a little and makes them easier to pierce with a needle.