Getting Your Fabric Ready
Don't skip the pre-wash, EVER, especially when it comes to denim! Pre-washing your fabric is especially important when working with denim because it will soften the fabric. Since denim is thick the softening makes it easier to work with. I usually wash my denim twice and without anything else in the wash. Pre-washing denim not only softens it but also removes the extra dye and prevents shrinking on your finished project. Many people suggest adding vinegar to the rinse to prevent the dye from bleeding. You can find hundreds of articles online on why you should and shouldn’t.
Denim is heavier than traditional cotton or cotton blend fabrics. Increasing your stitch length between 3-4 will help. The thicker the denim the longer the stitch needs to be. I like to take a scrap piece of my denim and stitch out on it before I begin my project. This allows me to make sure my tensions are balanced and I have a nice-looking stitch.
When you start sewing place both thread tails under the presser foot and to the back. As you begin sewing hold both thread tails in your hand, hold them firmly but don’t pull them. This will help in avoiding a bird's nest.
Always use a denim/jeans needle. As with choosing any machine needle, choose a bigger number for thicker fabrics and a smaller number for thinner fabrics. Denim needles are shaped differently from all-purpose machine needles. If you want to prevent broken needles, skipped stitches and ugly topstitching, do not skip changing out your needle. If you need more information on choosing machine needles check out: How to Choose the Correct Sewing Machine Needle
Use high-quality thread. I use an all-purpose thread for sewing the seams on lightweight denim and then use heavy-duty denim thread for the topstitching.
Only sharp tools will do! A good, sharp pair of scissors or a new blade on your rotary cutter will make cutting denim easier. Since denim frays a lot, zig-zag or serge raw edges right after cutting out pattern pieces, before even starting to assemble or cut out the pattern pieces using your pinking shears.
Pay attention to seams. Keep your iron handy and your seams pressed flat. Reduce bulk as much as possible by trimming seam allowances, clipping curves, and mitering corners. If you have two paired two seam allowances meeting try to offset them.
Do you have any tricks for sewing denim? I'd love to hear them!