Jeans and pants are a part of our everyday lives, and there’s more to them than just the fabric. Have you ever thought about the seams? They play a big role in how your jeans and pants look, feel, and last.
Excluding tailored clothing which is generally a single lockstitch with merrow stitching or binding over the edges, the two main kinds of seams in jeans and similarly constructed pants are flat-felled and overlocked seams.
If you’re thinking about tailoring your jeans or pants (especially tapering) or just want to know more about fashion, it’s good to understand these seams. Why? Because each seam type comes with its own set of benefits and challenges that can significantly affect the alteration process, durability, and aesthetics.
Flat-felled vs. Overlocked seams
Flat-felled seams are the most common type of inseam construction on jeans and similarly constructed pants. They are created by folding the raw edges of the fabric over, and on themselves, then stitching them together. This creates a strong and durable seam that is also very flat and neat. These seams are celebrated for their durability, fray resistance, clean finish, and aesthetic value. Flat-felled seams are often used on high-quality jeans in the light-to-midweight fabric range but can be a problem with heavyweight or thick fabrics because of the multiple layers of folded fabrics required to sew through where seams meet and the fabric’s weight.
When it comes to sewing through multiple seams, manufacturers of heavyweight denim will use flat-felled seams at the seat, even though they must sew through 12 layers of fabric where the yoke and center seat seams meet, and avoid the flat-felled seam on the inseam, where 8 layers of fabric must be sewn through in the crotch, for several reasons.
First, in the seat area of jeans and similarly constructed pants, the flat-felled’s low profile, smoothness, and visual aesthetic have more value than an overlocked seam. Second, because of the shorter distance regarding sewing, errors can be more quickly corrected compared to the long distance at the inseam.
Some brands, such as Bravestar and a few others, will take on the massive challenge of producing heavyweight jeans with flat-felled inseams. Sewing flat-felled inseams of heavy jeans during tapering is tough in our experience, not because of the fabric’s thickness, but due to the weight and gravity pulling on the jeans while they hang under the off-the-arm sewing machine. The weight exerts a continual tug on the fabric, which the sewer is attempting to hold upward into the folder, which causes the fabric edges to turn over, to create flat-felled seams. Shorter sewing distances, such as the rear yoke and center seat seams, are not a problem. Longer sewing distances, such as the inseam, have three to four times the weight and force pulling the fabric down and out of the folder. As a result, every time the sewer adjusts their hand position while sewing, the fabric slips down, or lower in the folder, causing sewing problems. This is most certainly the most significant explanation for why factories prefer to produce heavyweight jeans with overlock inseams.
Overlock seams, also known as serged seams, are another common type of inseam construction. These are generally used on the insides of the garment. Overlock seams are created by an overlock machine, which stitches the seam, trims the seam allowance, and encases the edge of the fabric with thread, all in one step.
The overlocked seam is more valued at the inseam on heavyweight jeans because it’s easier to sew. Also, it does not create as much bulk where the seams meet in the crotch, where there is lots of movement, unlike the yoke area of the seat, which sits flat. Lastly, the more unsightly appearance of the overlock seam is not visible on the inseam unless the jeans are turned up at the hem.
While not as durable or aesthetically pleasing as flat-felled seams, overlock seams are quicker and more economical to produce. They also provide adequate fray resistance, which is particularly important on the raw edges of denim.
The Importance of seam type in Tapering Jeans and Pants
What does this have to do with getting your pants and jeans tapered? To begin with, the type of seam influences the method and difficulty of making an alteration. The vast majority of tailors will taper jeans and pants from the outseam to avoid the inseam because of a lack of equipment, knowledge, or both. This is not an option with selvedge clothing since it would damage the selvedge. Unless flared, or garments designed for curvy bodies, the shape of jeans and pants legs is typically drafted in the inseam, leaving the outseams mostly straight up to the hips. As a result, modifications should also be made to the inseam.
Tailoring flat-felled seams requires a feed-off-the-arm sewing machine to be done correctly, and in order to maintain the original construction. It also requires skill and knowledge of the construction techniques used on mass-produced read-to-wear garments, which often have very different rules than tailored clothing.
Overlock seams, on the other hand, are easier and faster to alter. An overlock machine, which is one of the more common types of sewing machines available in many types of tailoring establishments, can be used to cut and re-sew the seam. Most tailors will struggle with how to handle the top stitch that is sewn on top of overlocked seams. Without an off-the-arm machine, it’s impossible to sew a fresh top stitch from hem to hem in a single pass, without taking the garment apart. Because they can only sew so far up the leg, heading upward towards the crotch, they must either link a new top stitch to the previous one. Alternatively, they can open the outseams all the way to the hips in order to fit the jeans or pants through a flatbed machine, sewing around the inseam, in a single pass.
Choosing to taper your jeans can give them a fresh lease of life, adapting them to changing trends or personal style preferences. But before you take them to a tailor, examine the inseam construction. Knowing whether you’re dealing with a flat-felled or overlocked seam will help you understand the complexity of the task and manage your expectations regarding cost, time, and final appearance. This way, you’ll ensure you’re making an informed decision about tailoring, helping your favorite denim remain a staple in your wardrobe for years to come.