Sewing Alterations: Fit Shirts to Your Body with Darts & Seam Adjustments | Maura Marcks | Skillshare

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Sewing Alterations: Fit Shirts to Your Body with Darts & Seam Adjustments

teacher avatar Maura Marcks, Clothing Designer

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Taught by industry leaders & working professionals
Topics include illustration, design, photography, and more

Watch this class and thousands more

Get unlimited access to every class
Taught by industry leaders & working professionals
Topics include illustration, design, photography, and more

Lessons in This Class

8 Lessons (28m)
    • 1. Introduction

    • 2. Tools for Alterations

    • 3. Front Darts

    • 4. Side Seams

    • 5. Shoulder & Sleeve Adjustments

    • 6. Replacing the Pocket

    • 7. Class Project

    • 8. New Conclusion and Thanks

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About This Class

Learning how to alter clothing to fit is a great way to feel confident in your style and breathe new life into second hand items. By putting a little time in to update a piece of clothing, you are creating something special, even if you haven’t made it from scratch.

This class will show you simple sewing techniques to resize shirts so you can look and feel great in clothes that you have lovingly worked on. This class is for people who have basic knowledge on how to run a sewing machine, and for people who are curious about one day making their own clothing and learning some sewing skills to help them on that journey.

To complete the project in this class and take the skills learned forward, you will need the following tools: 

  • 18x21" piece of fabric (Cotton or cotton blend with minimal stretch is suggested)
  • Seam Ripper
  • Fabric marker or chalk
  • Iron + Ironing board (or flat surface with a towel)
  • Scissors
  • Sewing Machine (setup with standard presser foot and regular point needle) 
  • Thread

Take the skills learned in this class on your next thrifting adventure - you’ll have more confidence and fun when you discover a really great shirt that needs adjusting. Having the control to fix how a garment fits is something that you’ll recall in future situations when clothing comes your way, and will perhaps build your sewing curiosity to some day make clothing from scratch to wear or sell!

Meet Your Teacher

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Maura Marcks

Clothing Designer


Hello, I'm Maura.

I design and sew sustainable clothing in Troy, NY.  My bright and happy clothes are made primarily with vintage and second hand fabrics. 

I learned to sew from my mom, who is an amazing seamstress! I developed my skills by altering thrifted clothing throughout my youth but started creating things from scratch in earnest after an inspiring visit to a David Bowie exhibit, wanting and knowing I could create fun and loud clothing for myself and others.

I create pieces that remind me of that perfect 70s or 80s needle in the haystack thrifted vintage shirt, shirts that scream “Dad on Vacation”. My pieces boast bright colors, soft fabric, quality stitching, and a custom fit!

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1. Introduction: [MUSIC] Learning how to alter clothing to fit your body is a great way to feel confident in your style and breathe new life into second-hand items. This class is all about simple sewing techniques to re-size shirts so you can look and feel great in clothes that you have lovingly worked on. My name is Maura Marcks. I design and sew clothing in Troy, New York. I primarily use vintage and secondhand fabrics to create unique one of a kind pieces. My favorite thing to make is a collared button down short sleeve shirt with bright and vivid fun fabrics. When I'm not designing and sewing my own clothing, I love to go thrift store shopping. Thrift stores are a great place to work on your style and save some money at the same time. In my class, I'm going to show you some simple sewing alterations that you can make to your thrifted finds such as front darts, side seams, and even a shoulder adjustment. You can take an ill fitting baggy but very cool shirt and turn it into something fabulous that fits you well. This class is for students that have used a sewing machine before and have confidence in using a straight stitch. If you've made a pillowcase before, you'll probably be fine. This class is also for people who are curious about one day making their own clothing and learning some sewing skills to help on that journey. Let's begin. 2. Tools for Alterations: I'm going to be altering this oversize button-down shirt that I made because I really liked the fabric and would love for it to fit me. I will be using this Bernina 910 sewing machine during the lesson but any basic sewing machine will do for what you'll be learning. Any of these alterations can be sown by hand with a needle and thread if need be. My machine is set up with a standard presser foot and a regular point needle, which is suitable for the fabric that I'm working with. I'm using an all-purpose thread and my bobbin is loaded with the same. I've got pins, sharp scissors, a fabric pen, which is disappearing ink with water or heat, and a seam ripper. Not essential but handy is a ruler. You'll need an iron and either an ironing board or a towel on a flat surface. Totally optional tools to finish raw edges would be a serger or pinking shears. If you don't have either, you can use your sewing machine to sew a zigzag or just leave the edges rough. In the next chapter, we're going to learn how to make our first alterations, the front darts. 3. Front Darts: I like to put on my oversized button down and take a look in the mirror to see where it's ill-fitting. This one is basically huge in the middle so I'm going to take in the front with two darts, and take in the sides. Darts are basically folds or tux that are sewn into the fabric to create shape. This pocket is right in the way, so we're going to take it off. I like to get settled in my chair with a seam ripper and carefully break the threads around the pocket to remove it without damaging the fabric underneath. You don't want to rush this part. If you rip every other stitch, you should be able to easily pull the back thread in one or two pieces. It will be sown more densely at the top. Now we're ready to fit ourselves for the front darts. To fit yourself for front darts, you can put on your shirt inside out and find the fullest part of your chest. You'll want to place a pin about an inch below that, catching just a tiny bit of fabric. The next part of the dart is marked at the smallest party, your torso typically just below your rib cage and just above your belly button. You can pinch this as close to your body as you want this seem to be, but keep in mind comfort and movement. I'm going to keep this shirt a bit loose and I'm placing a pin parallel to my body so I can try it on later. I'm following the natural grain of the fabric. You can give it a tug to find that nice straight line. I'll pin where I want the hips the shirt to hit. Now I'm just repeating on the other side, matching the pin locations. I'm going to lay my shirt down on a flat surface and reposition any pins as needed. Keeping the dart nice and straight along the fabric green. I'm going to repeat on the other side and make sure the darts are the same distance from the center. You want to mark the pin locations on both sides of the fabric with a fabric marker or a chalk. We're going to need to remove the stitches at the hammer, the shirt, otherwise, it'll give you a headache later and an uneven hem. I'm going to rip out the hem about an inch or more on either side of my markings. To prep your shirt for sewing darts, I'm moving my pins to be horizontal. You'll be able to sow right over these while keeping the fabric in place. Take out the top pin, and if you want, use a ruler to mark your sewing line. I'm going to load up my machine with thread and make sure that my bobbin is loaded with the same. I'm going to set my stitch to be a straight stitch. My machine has two spots to set this and I'm going to adjust my stitch length to a nice medium setting. I'm using a basic presser foot and a nice new universal needle. Now we're ready to sow the dart starting at the bottom edge of the fabric, start off slowly follow your markings and keep the fabric nice and taut. When you get to the point of the dart, you want to make the last few stitches as close as possible to the folds of the fabric and so right off the edge. I'm tying off the top of this stitch using a square naught so it stays put and trimming. You'll want to iron the dart with the extra fabric away from the center of the shirt. This is a good time to try on in the mirror to make sure everything looks okay so far. In the next chapter, we're going to learn another alteration which will be to take in the side seams. We don't want to mess with the armpits at this stage, so we'll start just below. This should look nice after this alteration. 4. Side Seams: To get ready to alter the side seams of the shirt, I'm going to lay it flat. The shirt has side slits which I'm going to seam rip to make it easier to do the alterations. I'm going to pin it nice and flat. We don't want to mess with this armpit area so I'm going to start the new stitch just below in the original seam allowance and make a nice gradual curved line with the midpoint being even with the midpoint of the front dark. I'm going to take an aside about an inch, but you can take it in as much as you need at this point. The curve will go all the way to the hips or the bottom of the shirt. I'm going to mark with my fabric pen. You don't have to draw the full line if you don't want to and just make a few marks along the way so you'll know what to sew. Use the first marks as a reference for the other side to make sure they're even. I'm going to pin as needed to keep everything in place. I'm going to grab my seam ripper and undo a good inch or more, the hemp on either side of where I'll be stitching. We just need all of the bulk to be out of the way when we go to the sewing machine. I'm going to try on the shirt one more time to just make sure everything looks okay before we sell it, and you can place a few pins vertical along your marks to try on and be careful not to get poked. I'm keeping my shirt on the loose sides so I'm satisfied but you can feel free to make any adjustments by just turning inside out and repositioning any pins you want to get the shape that you need. Normally, I wouldn't suggest making any cuts at this stage, but I'm going to cut off this bulky side slip because it's going to be in my way [NOISE]. You going to make any cuts, just make sure to leave at least a half an inch or so beyond your marks for your seam allowance. I've also rearranged my pins to be horizontal so we can sew right over them. I'm starting my stitch in the existing seam allowance and going back and forth to lock the thread in place. I'm just going to follow marks all the way down to the edge of the shirt, making sure to keep everything nice and smooth as I go [NOISE]. I'm going to repeat on the other side and iron my new stitch flat and press excess to the back of the shirt. If you have really bulky seams, you may want to trim them down and a serger is a great way to trim and finish off the raw edges all in one step. But a serger isn't your typical household items so a more accessible solution would be a pair of pinking shears, which you can get at any store with a sewing section or you can buy online. This create a zigzag cut which reduces frame. Another method is to trim your bulk with scissors and use the zigzag setting on your sewing machine down the length of the raw edges. I'm going to use my serger to do this part. I'm only doing this to the side seams. I'm not going to do anything with the darts because they aren't bulky. Not cutting it all is actually smart if you're expecting your body size to fluctuate as you might want the extra fabric to reset your alterations down the road. If you are serging, you'll have some extra thread that all needs to be tied off and trimmed. Now to fix the hem that we've undone, I'm ironing here to smooth everything out and I want to match the existing hem. In this shirt, the hem is folded over twice in equal amounts. I'm going to cut some of the uneven parts and use the iron to get a nice continuous hem. Once I have it nice and flattened out with the iron, you can pin and place at this point, but I'm just going to take it to the sewing machine. You'll want to adjust this stitch length to match the existing hem and also change your thread to match if necessary. I'm going to place my needle right over the existing hemstitch overlapping by about a half-inch or an inch. You can make a note of how large your hem is and follow the guides on your machine or you can mark the hem with a ruler if needed. You just want to make sure you stay nice and even while sewing the hem [NOISE]. Now I'm blending the stitch and sewing backwards to lock it in place. [NOISE] The next chapter we'll take a look at the shirt so far and learn another alteration to adjust the shoulders. 5. Shoulder & Sleeve Adjustments: Now that I've taken in the side seams, I'm taking another look in the mirror. It looks okay in the middle, but I think these shoulders are way too big. I'm going to show you how to pull those in without too much headache. We're going to get out a fabric pen and mark the edges of my shoulders. This is where a shirt is supposed to have a shoulder seam. We're going to mark and cut a nice moon shape off of the shoulder curving down but not all the way to the armpit. You can make initial marks while wearing the shirt and adjust afterwards by lying the shirt flat and inside out. I'm leaving the armpit area seams alone and I've used the seam ripper to take off about 3/4 of the sleeve. I've transferred my marks in this nice gradual curve starting at the shoulder location down about 3/4 of the way to the armpit. I'm going to mark a nice 1/2 inch seam allowance and these marks are going to be where I'll be cutting the fabric. I'm using the front marks as references to cut the same amount on the back of the arm hole. I'm taking my time here to carefully make my cuts according to my marks. Starting at the untouched part or the armpit, I've pinned the sleeve to the freshly cut shoulder. You may find as you pin that you have too much room on the new arm hole. Since this is the case here, we're going to need to sew the shoulder seam a little tighter to know how much I've pinned the either side of the sleeves so the excess is at the top of the shoulder, and I'm going to mark where the shoulder will need to be pulled in. Now I'm going to sew a straight line from the neck area down to the shoulder where I've marked it. I'm starting inside the seam allowance sewing back and forth to lock the stitch and sewing straight to my pin. You can trim this if it's unwieldy but I think we can make it work. Sewing the arm hole is tricky so we're going to adjust the seam length to be as long as possible which is called basting. This makes it really easy to seam rip if it doesn't work out in the first attempt. After I bast, I'll need to reinforce the seam with a tighter stitch. My sewing machine has removable platform to make it easier to work on sleeves or pant legs. If your machine doesn't have that, you can just sew this part with the default platform but just make sure you don't catch the other layers of fabric accidentally. Starting in the seam allowance, I'll set my foot down, so back and forth to lock the stitch, and begin to slowly sew the arm using a 1/2 inch seam. You can do this pinned or not pinned. I usually take my pins out because there's a lot of readjusting to do as you go to make sure the edges of the fabric stay together. I just take it nice and slow adjusting as I go. [BACKGROUND] Remember, I'm using a basting stitch here so we're really making a first draft of the final seam. Here is where we've tightened the shoulder. I'm making sure to sew this excess fabric nice and flat. In other circumstances, these excess might need to be trimmed first. [BACKGROUND] [NOISE] It's helpful to adjust as you go, sometimes pulling one layer of fabric more taut than the other so you don't get any bunching at the end of the stitch. [BACKGROUND] Now I'm blending the stitch into the seam allowance of the armpit area and sewing backwards to lock it in place. I'm going to repeat with the other arm and use my old cuttings as a reference to make it symmetrical. [NOISE] After both arms are basted and looking nice, I'm going to reinforce the basted seams with a tighter stitch. [BACKGROUND] [NOISE] After giving it an iron, I'm going to try this on again. All right. Those shoulders look much better. In the next chapter, we're going to replace the pocket and check out our newly altered shirt. 6. Replacing the Pocket: I'm going to place the pocket on the shirt and pin in place. I usually eyeball this, but feel free to get out a ruler and make sure it's on straight. I use the existing seams with the shirt as a reference point to line up the pocket. Readjust pins as needed into pockets where you want it. I'm going to place my presser foot very close to the edge of the pocket and about an inch from the top. My foot has a little marking that I'm going to follow to stay in an even line. You want to adjust your stitch length to be on the tighter side. I'm going to slowly cell backwards to the very top of the pocket and reverse. This gives a nice reinforcement stitch. [NOISE] I'm going to slowly follow the outline of the pocket and place my needle down to make any turns. [NOISE] You want to sew all the way to the very top of the pocket and reverse stitch to reinforce and trim any excess threads. [NOISE] There you go. That looks great. I like to roll up my sleeves and tuck my shirt in. Now we're tuck in. Next up is going to be our sewing project. We're going to sew some darts to reshape a flat piece of fabric using a pattern that I've provided. 7. Class Project: In this project, we will be sewing four darts in a piece of fabric following the PDF pattern I've provided. In just a few steps, you'll see how some simple stitches totally changed the shape of a flat piece of fabric. Practicing darts in this way will get you comfortable with the process and will then give you the confidence to make alterations to your drifted or gifted shirts. When you finish the project, please post a photo of your sewn fabric panel with the four darts visible. You'll need a printout of the PDF pattern that I've provided. You'll need a piece of fabric at least 18 by 21 inches. This is also known as a fat quarter, if you are familiar with buying fabric. You'll also need tape, pins, a fabric marker, chalk, scissors, a straight edge or a ruler, and thread. An iron is useful but not totally necessary. You'll also need a sewing machine loaded with thread and needle appropriate for your fabric. If you don't have a sewing machine, hand sewing with a needle and thread will work, but it's just going take you a lot longer. Assemble the printout of the pattern as shown in the layout example page, overlapping edges by 1/2 an inch, tape together. Cut out the paper along the solid lines. Fold your fabric in half. We're going to align the pattern piece to this folded edge. A lot of patterns will have you double up the fabric when the pattern pieces have symmetry to them to save paper. Pin the pattern to your fabric in a few locations. Cut out along the solid lines. I love my rotary cutter for this stage, but if you don't have one, scissors will do just fine. Cut out all layers of fabric along the solid lines, leaving the folded edge of fabric alone. Now, we have a sample shirt front. Go ahead and fold over so the wrong side of the fabric is facing out. We're going to mark the darts according to the pattern. In the class lesson, we did this by eye according to our body shape. But for this project we will follow these markings. Poke through the solid dots with something sharp, like a pencil. That way our marker or chalk and go through the fabric. Mark the edges and dots in both dart locations. Go over the markings if they're hard to see. Repeat on the reverse side, marking the wrong side of the fabric. Get out your ruler and mark the lines according to the pattern connecting the dots and marking your fold lines. Now, we have the four darts all marked and ready for the next step. Starting with one of the lower darts, pinch it so it's folded along the fold line and pin into place. Repeat this with the other lower dart. Makes sure the wrong side of the fabric is facing out. Make sure you're sewing machine is set up with a straight stitch, a medium stitch length, a regular presser foot and needle. Make sure both threads are out of the way and pulled tight. We're going to start with the bottom raw edge of the first pin dart. Set your foot down at the edge and sew back and forth to lock the stitch. Following your markings, you can sew right over the pins. [NOISE] When you get to the end of the dart, slowdown and carefully get right to the very edge of the fabric. Sewing right off the end. Leave a generous amount of threat attached because we'll tie it later. Repeat with the other pinned dart. We're going to repeat the process with the other two darts, pinching and folding along the markings and pinning in place. Sew the darts starting from the outer edge to the point. [NOISE] Carefully sewing right off the edge. [NOISE] Tie off each point in square knots to keep them from unraveling. Trim extra thread. If you have an iron handy, iron the lower darts away from center and the upper darts can be iron down towards the bottom of the shirt. We've made our darts. You can see how just four simple stitches have turned a flat piece of fabric into a three-dimensional curved garment piece. When you finish the project, please post a photo of your sewn fabric panel with the four darts visible. 8. New Conclusion and Thanks: Okay, I hope you've enjoyed this class. We've gone over front darts, side seams, how to make a shoulder adjustment. We replaced it, put on a pocket and we've even adjusted the hem of a shirt. I hope the lessons you've learned in this class will give you the courage to go to a thrift store and pick out something that maybe doesn't fit you write and practice a couple of these alterations. Have a good one and keep sewing.