This seamless trim technique is a method I’ve been using for years to add custom trim to my costumes without any top-stitching at all. Similar in a way to bias tape, but with many key differences in implementation and results. No one taught me this technique, but now I’m teaching it to you! Please read through all the instructions below before asking any further questions, and happy trim-making! C:
I love bias tape. Bias tape is great for adding a colored edge cleanly to any costume.
(This is coming from someone who avoids top-stitching like the plague.)
When done right, bias tape looks great!! But sometimes garments are shaped too strangely to use bias tape easily — or maybe you don’t want those nasty seams at all of your corners? (Okay, they’re not that nasty, but I am driving a point here). You can always create your own custom trim that will seamlessly fit your garment. (If you’ve never used bias tape, I suggest you familiarize yourself with how that’s done, and then revisit this tutorial)
This technique is probably most relevant for jackets, but apply it whenever you see fit!
The example I’ll be using for this tutorial is the middle piece of my Fire Ferret costume (pictured here with my buddy discordantkettle as Bolin!)
step 1: patterning your trim
Once you have your pattern for your garment, you can can begin the process of creating a pattern for the trim. The garment pattern itself should include extra seam allowance on all the edges the trim covers. Think of the overall process of making the garment being like making a pillow. You’ll need two pieces of fabric (your good-side and your lining) with seam allowance along all the edges so you can sew them together and flip it inside-out. This is one of the key differences between this technique and using bias tape, which encases a rough edge.
To start your trim pattern, you’ll want to make a copy of your garment pattern — or at least trace the part the trim will go, on to another piece of paper. From there, the first thing you’ll want to do is measure the seam allowance from the edge all along the edge where your trim will go. (It should use the same seam allowance you used in your garment pattern— I use 1/2 an inch because it’s easy to measure and is a good buffer amount if things don’t line up perfectly). The green dashed line in Fig 1a below is my seam allowance. This is also the line I will be sewing along during one of the final steps.
Next, measure the width of the trim itself. For this project, my width was 1.5 inches, as seen by the red line below. This area is what the final trim will be. If your trim is not a consistent width throughout, now’s the time to draw it how it goes. Maybe it’s thicker as it reaches the tip of a corner, etc. Note that certain types of curves will be very hard to sew, so this technique is most suitable for straight lines!
Finally, you need to build one more seam allowance into your trim pattern, on the inner edge. This will be the “inner seam” that is folded and understitched like bias tape. So extend the red line by another 1/2 inch to make the yellow line. You’ll also want to cut notches out of the corners so you’ll be able to fold the corners later on (seen in Fig 1b and 1c). Cut out your pattern, and you’re ready to move on to the next step!
step 2: cutting your trim fabric
I don’t have pictures of this, but I think you know how to cut out fabric ;) The only note to make is if you are cutting your trim pattern on a fold, like I was, be very very careful. It’s a real pain, but can be done. Silkier fabric will be more difficult, as well. Just take your time, and use lots of pins! Also, it will feel like you are wasting a lot of fabric, hahah, due to the strange shape the trim pieces will be.
step 3: folding the inner edge
Now that you’ve cut your trim fabric, you can fold and iron the inner edge. This is the edge that will be “under”-stitched on your garment. You should have cut notches out at each of the corners, so start by folding the flap up, and set some pins down to hold in place. Be sure the wrong side of the fabric is facing up. Now iron to press the folded edge into a nice crease. Try not to push on the pins too hard to avoid leaving marks, and remove the pins once the fold is starting to hold, and iron some more. Do this all along the inner edge, being careful to not let the corners fray too much.
step 4: pinning the inner edge
At this point, you should have your garment and lining at least partially sewn, depending on where and how the trim is being applied. If you are adding trim to the outside edges of a jacket, for example, you should have the whole good-side of the jacket sewn for this step. In this case, I needed to sew the center seam before adding the trim, but the front and back pieces have not been sewn together.
To start pinning, first line the trim up along the appropriate edge of the garment, like seen below. I usually will lightly pin the trim down from the outside to keep it in place. Then, one at a time, I remove each pin and replace it, but this time pinning only the “inner flap”, by reaching between the trim fabric and the garment fabric. This is a slightly tedious process of removing and adding pins.
Also, I usually pin in the direction of sewing when doing this, rather then perpendicular. You’ll have to remove pins as you sew, but I find it’s easier to see that the trim is in the right place!
step 5: sewing the inner edge
This part should be fairly easy. Just sew right along the folded crease you
ironed in Step 3. Go slow, no need to rush. It’s important to have this sewn
as perfectly as you can!
Convex versus concave angles.
Take particular care when sewing the corners. The corners you see below
are are normal “convex” angles. The angle points outward, creating a tip
on your garment. Most of the angles you’ll be working with will probably
be convex, of varying degrees. That’s GOOD. Those are the easy ones to sew.“Concave” angles point inward, and are difficult to understitch because the fabric doesn’t have a lot of give at those corners. I’ll explain more in step 6!
step 6: concave corners, oh no!
Below is an example of a concave corner. You see that it points into the garment rather than away from the garment. These are tricky to sew!! In the past I’ve gotten so frustrated that I just Heat-n-Bonded those corners. This time I was determined to sew it with my machine. Because it wasn’t a total right angle, I was able to get my machine in there, but it looked pretty bad! Next trial I did, I hand-stitched (with the ladder/hidden stitch) about a inch or so on each side of the corner, before sewing the rest on the machine. That also didn’t look all that good.
Finally, I decided to machine understitch close to the concave corner, and then handsew the tricky part afterwards, and that gave the best result — because you can kind of pull taut where need-be, etc. You can see below where the hand-stitching begins and ends, but trust me — no one will notice when it’s all said and done and you’re wearing your costume!
step 7: finish sewing trim on garment & lining
Now is when you finish understitching all the trim, and sew whatever you have left for the garment itself. The order will really depend on what you’re making. However, you’ll need the completed right-side of garment and lining before you can proceed. Most likely, you won’t need any trim on your lining, unless you’re doing a cape or something.
We wanted the yellow trim on our lining (maroon below) so that the edges of our garment didn’t have a stark contrast of colors. If your lining color greatly differs from the outside, the edge may be slightly noticeable. But it’s something you’ll have to keep in mind for this technique.
For comparison, below is the “seamless” technique (red) versus simply top-stitching the trim on (maroon). If you can sew straight enough, top-stitching may look okay. However, I think if you can avoid top-stitching all-together, your garment will look that much better!
step 8: marking your final edge
NOTE: It’s good practice to iron your trim flat before moving onto the final steps!
Remember your pattern from Step 1? Remember that green line I told you to draw? Well, this is the same line you’ll be marking on the wrong side of the garment in this step. Get out your trusty ruler and measure the trim width from the stitch you sewed along the inner edge (in this case 1.5 inches). You could measure the seam allowance (.5”) from the edge, but measuring from the inner edge insures that your trim will be perfect! Mark with chalk, pencil, what have you, every inch or so. Depending on the colors, it can be hard to see this mark when sewing, so mark it well!
step 9: pinning and sewing outer edge
You’re almost there! Start pinning by tacking the trim in place with a few pins. This helps ensure your trim is taut. Then pin the garment and lining together along the outer edges. Of course the two right-sides should be facing each other. Remember you are essentially making a “pillow”. This means you’ll need a hole to flip the garment through. I often leave a 6 inch gap somewhere on the lining that I later hidden/ladder stitch close. You may have to leave a section open on this final seam, if there’s no where else to put the hole.
Now it’s time to simply sew along the marked line you made in the previous step. Easy!
step 10: cutting corner tips
Once you’re done sewing the outer edge, you’ll need to cut the tips of each of the corners of your garment before flipping it inside out. You’ll see below how you should cut a convex and concave corner. The convex corners you should trim because otherwise they are bulky and the point/tip will be very blunt if you don’t. The concave corners HAVE to be cut, or else they will not lay properly and just pull things in a very weird way. Beware of cutting too close to the seam because you’ll risk the threads poking through once you turn it inside out. So, cut a little triangle out of each of the corner tips, and them move on to flipping the garment.
step 11: flipping right-side-out and ironing
So close! You now just have to flip the garment through the hole you left so the right-side is on the outside! And if you’re lucky, you won’t run into the “infinite tube” nightmare that occurs when you try to flip any tubular garment inside-out, which happened to me with this garment. Because I’m dumb!
If all is well, which I hope it is, the final step is to iron the outer edge so that everything lays crisp and clean! Get out your iron, and a chopstick or the like is useful too! Use the chopstick to poke the corners out to the seams (but not too roughly or you might rip the seam). Iron the seam as perfectly as you can, especially if the lining is a different color from your garment.
And there you have it! A garment with trim that has been added seamlessly! This is a great technique for many projects, but may not be right for every one of them. This technique is also fairly time-consuming and can waste a lot of fabric. But, be creative — this process can be applied and altered to suit various needs! And it’s great for someone as anal-retentive about seams as me!
Good luck with your projects, and if you have any questions, send an Ask my way, or you can Note me at firewolf826.deviantart.com, and I’ll try to help!