Sewing a Mock Flat-Fell Seam

Heavier weight fabrics that tend to fray a bit can often benefit from a flat-fell seam, just like you'd see on the sides of your jeans. But what if you don't want the seam on the outside of your garment? Well, you can achieve the same basic look with the seam on the inside. This is called a mock flat-fell seam, though some call it the mock jean seam.

The process for putting this seam together is very much like the flat-fell seam, except you work on the inside of your garment. This means you start with a standard seam, sewn right sides together. So if you decide after you've already started sewing that you want a flat-fell seam, and you don't feel like taking everything apart, you can settle for a mock flat-fell seam.

To create this flat and secure seam, press both raw edges to one side. I like to press them toward the back of the garment, but it doesn't really matter. Just make sure you press all your seams in the same direction. It makes everything look nicer in the end.

You should now have the raw edges of your seam allowance together, one on top of the other. Trim the bottom seam allowance to ⅛". Careful. Don't cut the top one, because you'll need that seam allowance to encase the other. Fold the uncut seam allowance around the other and press so that the uncut seam allowance is folded in half and fully cases the edge that you cut. Press firmly so that it doesn't move around on you.

Now to stitch it in place. Topstitch as close to the folded edge as you can, going slow and steady so you don't miss. Also topstitch on top of the original seamline. This will give you a nice finished seam inside and two perpendicular lines of stitching on the outside. All nice and finished with no raw edges visible inside or out.

This is a good choice for sporty garments or garments you want to  make reversible. It takes a little work and some precision stitching, but it's excellent practice and is well worth the effort.

Sewing a Flat-Fell Seam

If you've ever seen a pair of jeans, you know exactly what a flat-fell seam is. It's the seam that lies flat on your jeans, totally encased within itself. This seam is strong and sturdy, typically used on sports clothing or reversible garments. Some people call this the jean seam simply because it's used on almost every pair of jeans you'll ever buy. It's a good looking, professional seam. Though it looks complicated, it's actually as easy as any other enclosed seam. If you've ever sewn a bias bound seam, you'll be able to full off the flat-fell seam.

Unlike some of the other seam finishes, you actually have to know you're going to use this seam finish before you ever start your garment. This is because the raw edges of the seam have to appear on the outside of the clothing. To accomplish this, simply sew the item with wrong sides together instead of right sides together, but only on the seams where you want a flat-fell effect. If you're making jeans, you'd probably only do this on the side seams. The inseams and crotch seams are not usually created using this method. Check your favorite pair of jeans and you'll see exactly where the flat-fell is typically used. Of course, since you're making your own garment, you can use the flat-fell seam wherever you like.

Once you have your chosen seams on the outside of your garment, press both raw edges to one side. Usually you would press both edges toward the back of your garment, but the choice is yours. Just be consistent. After pressing, trim the lower seam allowance to ⅛". Fold the upper seam allowance around and under the lower seam allowance. You'll basically be folding the upper seam allowance in half and tucking the lower allowance inside it. Press again, then topstitch through all layers close to the fold, essentially sealing the seam allowances inside themselves. Topstitch once again close to the seamline just to make it all look pretty and that's your flat-fell seam.

This seam is excellent when you have to hide your seams completely, especially for those garments you want to lie flat against your skin. With this type of seam, after all, there are no seam allowances inside the garment to brush against you.

Sewing a Hong Kong Seam

Seams may appear straightforward, but they can be tricky things. Not in the sewing of them, because that's quite easy, but in deciding exactly what type of seam might be most appropriate. You might need a common seam, such as a clean finish seam, or an enclosed seam like one bound in bias tape. Perhaps an overlock or a French seam would suit you better. But how do you choose? Well, that depends on the type of fabric and the item you're sewing, of course.

If you're using a heavyweight fabric, and if the item in question is an unlined garment, you might decide upon a Hong Kong seam. This finish totally encases the seams, giving your garment a pretty, almost couture, finish on the inside. It should be noted that this particular seam finish works only on straight or moderately straight seams. Curved seams have to be notched to lie properly, and the notching means that a Hong Kong finish is not really possible.

But if your seams are mostly straight, and your seam is pressed open nicely, you can cut a continuous length of bias tape. The tape should be a full inch wide, maybe even a little wider, and it should be pressed open. This may seem a little wide for a seam, but the extra width gives you much needed excess when you start working on the wrong side of the seam. You can always trim it down later. You don't have to use actual bias tape. You can cut your own strips of fabric to use if you want something coordinated to the fabric you're using. Maybe even use remnants of the main fabric, or a pretty silk to make your seams even prettier. It's up to you. If you're cutting your own strips, 1½" is probably the best width to work with. Remember, you will be able to trim it later.

With the seam pressed open, line up the edge of the bias tape with the raw edges of the seam, right sides together. Stitch ¼" from the raw edge, but only on one side. Now open up this new seam, revealing the right sides of both the fabric and the bias tape. Press open, then fold the bias tape under the raw edge and press again. The seam should now be enclosed in the bias tape. To secure, stitch in place from the top side, making sure your needle hits precisely where the fabric hits the bias tape. This is called the 'ditch', and stitching here should make your stitches all by disappear. Nice and neat. Trim off the excess and repeat for the other side of the seam. This is your Hong Kong seam.

Though this seam is a little more work than the less fussy bias tape bound seam, it is neater and exactly the type of seam finish you might need if you're creating an unlined garment where the seams will occasionally be seen. If you want to jazz it up even more, consider using silk or another fine fabric as your bias tape. Though this isn't necessary, a finer fabric enhances the finish and makes your garment appear designer. Which it is. Designed by you, anyway.