Sewing

Overlock and flat-felled seam types by highlighting the hem of a pair of jeans sewed with an overlocked inseam on the left and a flat-felled seam on the right.
This image explains the overlock and flat-felled seam types by highlighting the hem of a pair of jeans sewed with an overlocked inseam on the left and a flat-felled seam on the right.
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Definition of inseam types: Overlock & flat-felled seams

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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.

In Summary

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.

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A close-up of professional chain stitch hemming alterations highlights what chain stitching is by displaying a thick golden yellow chain stitch on the hem of blue jeans.
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Chain stitch hemming – how it’s done

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In this brief social media video, we show how to hem jeans professionally, just like it’s actually done at denim factories. In our video, there is no need for work-around-sewing-techniques, which leave bulky seamlines over the hem or ragged fabric on the reverse side, which prevents cuffing or rolling the hem. We love denim at Williamsburg Garment Company and hemming jeans the right way is important to us.

Even the heaviest denim is no problem for our beast of a sewing machine, a customized Union Special 56300 that bores through multiple layers of folds and seams. Here, denim designer Maurice Malone demonstrates chain stitch hemming a pair of jeans in our Instagram and TikTok video. Make sure to stay tuned and follow us for more.

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The finished result of a professionally tailored heavyweight Oni Denim jacket with alterations to take in the body and sleeves.
Professionally tailored heavyweight Oni Denim jacket.
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Can you tailor denim jackets?

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“Can you tailor denim jackets?” is a frequently asked question at Williamsburg Garment Company. Our answer, as with all denim products, is, of course, yes, but jackets and shirts are more complicated. They have armholes and shoulder widths that correspond to the width of the body. When you narrow the body width evenly, the armhole shrinks and the armpit curve is negatively affected. At the same time, the shoulder width remains constant, resulting in wide shoulders compared to the body width. The only way to avoid this is to remove the sleeves and, if possible, draft new armholes and sleeve shapes. Otherwise, you can leave the armhole alone and narrow the body unevenly from the chest/armholes down.

Nothing about modifying denim jackets is simple or easy. The body width is linked to the armhole and shoulders, whereas the sleeve length is linked to the button placket length and/or the armhole.

Can you tailor denim jackets on a home sewing machine?

When it comes to DIY denim jacket alterations, the short answer is that you can do it, but it is not recommended. If you’ve done any research on the subject, you’ve probably discovered that all of the videos and advice you’ve seen have had poor results on cheaply made garments.

Flat-felled seams on the sides, shoulders, and sleeves distinguish traditional jean jackets. This design eliminates the option of doing high-quality alterations on home sewing machines, at your local dry cleaners, or at the best, most reputable tailoring shops. Most denim alterations specialists lack the factory equipment (a Feed-off-the-Arm 3-Needle or Double Chainstitch Industrial Sewing Machine) to duplicate the double-needle flat-felled seam with chain stitching and must come up with an improvised method to sew them.

Most denim jackets and jeans are produced with fabric that is too thick for home machines. To tailor denim on a home sewing machine, you would need to avoid thick seams or deal with really thin, lightweight denim fabrics.

Thread size is also an issue with DIY and most tailoring shops. Denim is typically sewn with thicker thread sizes than most other garments, which contributes to its distinctively sturdy appearance. Home machines are not designed to handle the needle sizes required for thick threads. They also lack the ability to puncture through layers of denim using wide-diameter needles with large eye holes. Thin thread sizes and short stitch lengths are two of the reasons why denim does not look like denim when it is not sewn with the proper threads.

How altering a jean jacket professionally is done

The owner of this heavyweight Oni Denim jacket adored it, however, he had a small frame and required the chest and arms reduced. Here are the steps we used to customize his denim jacket:

1. Chain-stitched flat-felled seams close the sides and sleeves of traditional jean jackets. Because the band at the bottom is chain stitched to the jacket, our first step was to remove the chain stitching connecting the waistband to the body, just enough to remove excess fabric and resew the seams closed.

2. Following that, we split the waistband and removed the chain stitching that held the flat-felled seams together from the waistband to about 6 inches from the cuff seam. After narrowing the excess fabric around the bicep, just past the elbow, we could neatly flow into the sleeve.

3. We press flat the flat-felled seam folds in order to draw the new shape from the waistband up to the armpit and then fade out the shape before reaching the cuff.

4. The seams were then closed (as indicated in the image below) by stitching fresh double-needle chain-stitched flat-felled seams using the same thread size and color as the original. If you look closely at the yellow chain stitching, you can see where the new sewing blends in with the old.

How to tailor a denim jacket is explained through this photo of an Oni Denim jean jacket, which is in the process of being tailored, to deduce the chest and sleeves.

6. After cutting away the extra fabric of the bottom band, we rejoined and resewed it to the body with single-needle chain stitching.

7. Finally, the band tabs along the side seams were reattached. Again, if you look very closely, a seamline where the waistband was split and resewn can be seen near the two yellow stitch lines that attach the tabs. Take note of the new chain stitching that joins the old one below the pocket bag.

Williamsburg Garment Company’s objective is to make alterations to improve fit while retaining the original style and construction. This entails matching thread colors and sizes and stitching seams back the same as the original factory sewing.

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A close-up of two red bar tacks stitched onto the hem of a pair of Gustin jeans highlights what a bar tack is.
For branding and to secure the chain stitch, Gustin blue jeans are commonly sewn with a red bar tack on the hem.
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What is a Bar Tack (Bartack)

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What is a “bar tack” (also spelled “bartack”)? This is a question we get almost every day because our denim service is one of the very few that offers bar tacking. The close-up image above shows two red bar tacks sewn onto the hem of a pair of Gustin blue jeans. When you choose to add bar tacking in the dropdown box of our chain stitch hemming service, this is the type of stitching that will be added.

First, an explanation for the majority of our customers who are interested in having their jeans hemmed. The close-up image above shows two red bar tacks sewn onto the hem of a pair of Gustin blue jeans. When you choose to add bar tacking in the dropdown box of our chain stitch hemming service, this is the type of stitching that will be added.

Brands like Gustin, Nudie, and Brave Star jeans have bar tacks sewn over the chain stitching on the hems, both as a branding identifier and to reinforce the sewing. Although they add a bit of extra security by preventing the chain stitch from unraveling, they are not found on the vast majority of jeans. We usually inform our customers that it is not necessary to add them.

"What is a bar tack?" pointed out on Nudie jeans with bar-tacked chain-stitched hem.
Nudie blue jeans are typically sewn with a chain stitch that extends off the hem with a bar tack on the seam.

Definition Summary

A bar tack is a machine-made stitch with a zigzag pattern used to reinforce areas on clothing that experience high stress, such as where belt loops join, pocket corners and flaps, hip seams, and the fly of jeans.

bar tack | bär tak | noun a zigzag stitch made by industrial sewing machines to strengthen areas of a garment with potential weak spots or other sewn items.

bar-tacked adjective

bar tacking noun

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Cover image for TikTok video demonstrating how we expertly taper and take in the waist of jeans for the perfect fit.
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Getting your fit right: Learn how we taper the leg while taking in the waist on jeans

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Do you want to know what sets us apart from the competition when it comes to denim alterations? In our latest TikTok video, you can see how we professionally taper the legs of a pair of jeans while also taking in the waist to make them fit just right.

@williamsburggar Denim heaven. The art of taking in the waist with tapering alterations on jeans. We perfect your fit. #denimyourway #denimhead #denimtailor #taperingjeans #jeanswaist #jeanswaistgap #selvedgedenim ♬ MAMBO OVER THE MOUNTAIN – Rick Hirsch

Make sure to follow us on TikTok to see more informative and entertaining videos. @williamsburggar

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Close-up of a black vintage Union Special 43200G sewing machine used for chain stitch hemming on jeans

The Union Special 43200G: A Unicorn or One-Trick Pony?

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Denim nerds, get ready for a reality check. I’m about to debunk some of the myths and misconceptions about the Union Special 43200G that have been circulated for years by brands, publications, and online communities.

As is the case with many things on the Internet, exaggerated claims can quickly become folklore by the regurgitation of stories that weren’t well thought out from the beginning.

The well-told narrative that the twisting at the hem is caused by a technical error, feed dog flaw, or differential defect in the inner workings of the Union Special 43200G is flawed in and of itself. The roping effect has been overcomplicated to the point where denim fans who don’t know any better will believe that the Union Special 43200G is the only sewing machine capable of producing twisted and puckered hems with chain stitch hemming.

In my research into what denim enthusiasts are being led to believe, I easily discovered statements that I believe are misleading or false. Here are a few examples:

“Any Union Special without the folder will not create the roping effect.”

“There is only one way to chain stitch a selvedge denim hem and that’s on a folder equipped Union Special 43200g. Why you ask? These machines create a desirable roping effect on the hem which is actually caused by a feed differential defect.”

“Roping comes from the 45 degree angle of break-in that makes the hem look like a rope. It’s become part of true denim DNA. Without it, jeans don’t look right to us. And the crazy thing is this comes from a flaw in the Union Special that makes it create a slight twist.”

“Union Special company seems to have replaced the 43200G with other machines in a quest to replicate the same stitch and make it easier to use the machine but this has reduced the tension on the thread. This means you don’t achieve the same roping/puckering as you would with the original.”

In reality, the roping effect is simply caused by seams that are not lined up.

Example of a misalignment of both seams on a jeans hem will cause a shift and rotation in the direction of the misalignment. This is the roping effect on denim.
The graphic shows how misaligned hem seams create a shift and rotation. This is the roping effect on denim.

The roping effect is simply caused by seams at the face and undersides of the hem not being lined up. Twisting occurs when the inseams shift in one direction, resulting in the roping effect. The effect becomes more visible with aging and washing. Sometimes factories do this unintentionally, and other times a brand’s designers may request a factory do it on purpose. Most factories make an effort to align the seams, which may be the reason why most jeans do not exhibit a significant degree of twisting.

Close-up example of the roping effect on a pair of light-washed Levi's jeans with chain stitch hemming and frayed hem.
Example of the roping effect on a pair of light-washed Levi’s jeans with chain stitch hemming and frayed hem.

Furthermore, the stitch type is not a factor in creating the twists and puckers, as seen in the reference example photo below. I, too, was once swayed by rumors and stated in my tapering video that the tension of chain stitching contributes to the roping effect.

Busting the myth that the Union Special 43200G does not cause roping effect by showing twisting on a hem sewn with a lockstitch machine.
These hems without chain stitching show that the puckers and twists that make up roping are not caused by the type of stitch.

Don’t misunderstand me. I think the well-beloved Union Special 43200G is a beautiful old sewing machine. However, production was halted for a reason. It was most likely not due to a differential flaw, cheaper lockstitching, or other nonsense being repeated or made up. The truth is that it only does one function. Although it performs well, some sewing machines can perform the same function as well as other operations.

Black vintage Union Special 43200G sewing machine used for hemming denim jeans.
Black vintage Union Special 43200G sewing machine. Photo courtesy of Joswick denim.

Purchasing a sewing machine that only does one thing over machines that do multiple tasks equally well or better is a bad idea for factories that must make sound economic decisions. This is most likely why production was halted, as with most discontinued products.

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