What is a seam finish?
A seam finish is something that you do to the raw, unfinished edges of the fabric of your project to prevent fraying. It’s no fun to spend hours completing a beautiful sewing project only to find that your seam allowances have become ragged and maybe even unraveled through the stitching the first time you throw it in the wash. Making sure to finish your seams as you sew will keep this from happening to you!
Now, when should you finish your seams? It’s important to finish each seam before you sew another seam that intersects it. That way the finish will be fully incorporated into the project and look professional. You can either finish all of the raw edges before sewing your pattern pieces together or you can finish each seam after you sew it.
Top 3 seam finishes for woven fabrics
When working with woven fabrics, it’s very important to finish your seams because they almost always have at least some tendency to fray. While there are many different options for finishing your seams, these 3 methods are our top picks – they work well and are simple to sew.
- Pinking shears
Pinking shears look almost like a pair of scissors – except that they have teeth which allow them to cut fabric in a wavy pattern instead of a straight line. When woven fabric is cut on the bias, it reduces the tendency of the fabric to fray. When you cut your fabric with pinking shears, it creates little triangles so that the cut edges are all on the bias and won’t fray as much.
This seam finish is super easy and fast; however, it works best for tightly woven fabrics that tend towards light fraying only. Loosely woven fabrics with a high tendency to unravel will likely still fray when cut with pinking shears.
To use pinking shears, first sew your seam like normal.
Next, cut your seam allowances down by half using your pinking shears.
Finally, press your seam allowances open or to one side. Personally, I prefer to press mine open because I feel that the press I get is crisper and flatter.
- Serger/overlocker
One of the easiest, fastest, and most professional-looking seam finishes you can use is finishing with a serger (also known as an overlocker). The serger sews an overlock stitch, which loops 2 to 4 threads around the edge of the fabric – I prefer a four-thread overlock stitch for better coverage of the raw edges. This stitch is strong and very effective at preventing fraying. The downside is that you’ll need an overlocker machine for this purpose, which can be spendy. I would recommend getting a serger once you’re sure you’ll be sticking with sewing long term.
When I finish seams with a serger, I prefer to overlock the edges before I sew my seam. It’s just easier to work with flat fabric pieces and helps you avoid accidentally cutting through your project with the serger blade.
Once you’ve sewn an overlock stitch along the edges of the fabric, you can then sew your seam as usual and press the seam allowances open.
- French seam
If you don’t have a serger and are working with a fabric that is not optimal for using pinking shears, a French seam is an awesome, professional-looking seam finish. This finish encloses all of the raw edges within the seam, so it needs to be done as part of the process of sewing your seam, rather than before or after stitching.
To sew a French seam, first sew your seam with wrong sides together using a 6mm (1/4 inch) seam allowance.
Trim the seam allowances down to 3mm (⅛ inch).
Next, press the seam allowance open, then flip the fabric around so that your fabric is right sides together. Press the seam again, this time pressing your first seam right to the edge of the fabric.
Stitch your seam again, this time with right sides together, taking the remaining seam allowance (the original seam allowance minus 6mm).
This encases all of the raw edges inside of the seam. You can now press the seam allowance to one side.
Top 3 seam finishes for knit fabrics
Let’s talk seam finishes for knit fabrics. Knits are easier to finish than woven fabrics, which is one reason I love sewing knits!
- No finish
One of the best characteristics of knit fabrics is that they don’t fray! Because of this, with knits you can actually skip the seam finishing step if you like. Just keep in mind that an unfinished seam allowance won’t look quite and polished and professional as a finished one.
If you plan to skip seam finishes, simply sew your seam like normal using a zigzag or another stretch stitch.
Trim the seam allowances to about 6mm (¼ inch) away from your stitching to reduce bulk.
Finally, simply press those seam allowances open or to one side.
- Serger/overlocker
A serger is a versatile tool – it’s wonderful for finishing knit seams as well as wovens. An overlock stitch is my favorite way to finish my knits – in fact, a serger makes sewing knits fast and easy because you can sew your seam with your serger and avoid your sewing machine entirely.
To do this, simply sew your seam with right sides together on your serger, going through both layers of fabric. It’s best if your seam allowance for the project is 6mm (the width of most overlock stitches on a serger), but you can trim away the excess seam allowance with the serger blade as you sew if you need to.
Next, press that serged seam allowance to one side. It’s a beautiful, lightweight finish for knits!
- Zigzag stitch
Finally, if you happen to have a knit that does fray a little bit, or you’re making something that will receive heavy wear and tear, you can strengthen the seam with a zigzag stitch.
Stitch near the raw edges of your fabric pieces first, making sure to stay within the seam allowances. Next, sew your seam like normal using a zigzag or stretch stitch.
Finish it off by pressing those seam allowances open!