Slot seams are a seam that is decorative with a pop of color inserted underneath. They look a little like a tuck or pleat but are constructed slightly differently by creating folds on either side and stitching a piece of fabric underneath. Slot seams are common decorations on shirts and dresses and are easy to sew.
The slot seam is a functional and decorative seam very similar to the lapped seam. The difference is a piece of added fabric is placed between both sides of the seam edges of the lapped fabric.
The insert of a fabric piece behind the lapped pieces adds extra strength and a contrast to the seam. The backing used to create the slot can be a different color or texture, or the same as the garment. The slot creates a decorative slit in the seam. It is easy to up the style and effect of the seam simply by changing the color of the cotton to sew in contrasting thread color.
This slit may be down the leg or side seam of a garment. The seam is folded at each side and attached to the slot fabric. The distance from each side of the seam is entirely personal and depends on the overall look of the garment. Slot seams are often used to show a flash of color in sporting tracksuits when team colors need to be on show.
Slot seams add a tailored look to a garment. It is used to decorate pockets, jackets and coats, dresses and blouses. It is a fun seam to master and use for an extra pop of color. The slot seam will not add width to the seam as you will see when you try this decorative lapped seam out.
How to Sew a Slot Seam
These steps will help you make a sample slot seam before trying this type of seam out on your garment. It is always wise to test your seam style on a scrap of fabric first. Keep the sample as a reference for any future slot seams.
Steps to follow to make slot seams:
Step 1 - Fabric Choices and Cutting
Choose scraps of contrasting colors to make your practice sample. This will help you see the steps you take to get the slot seam right. This explanation uses pink for the main and green for the contrast.
Cut a piece of contrast fabric (green) 1 ½ inches (4cm) wide by the height of your main fabric. The contrast fabric width needs to be at least two times your seam allowance.
Step 2 - Mark
Take tailor’s chalk or a water-soluble marking pen and mark a seam allowance line along the length of each of the main pieces of fabric. In this example, this is the pink fabric. The reason that we mark the seam allowance is that when finishing the edges in the next step, some of the seam allowances may be removed.
In order to sew slot seams, the seam allowances must be at least ⅝ inch (15mm).
Step 3 - Finish the Edges
Finish the edges of the seam allowance you have marked. Also, finish the edges of your contrast color. If you are using a serger, just trim the minimum amount you can.
Step 4 - Baste the Seam
Place the main (pink) fabric right sides together. Now using a basting stitch or the longest stitch length on your machine, stitch the seam. Do not backstitch because this line of basting will be removed.
Press this seam wide open. Set this piece aside.
Step 5 - Mark Contrast
Mark the middle of the contrasting (green) piece by folding and finger pressing just to guide you when you match this piece to the basted seam.
Step 5 - Align
The seam of the basted fabric is going to match the finger-pressed seam line just to get the smaller piece, the slot piece, to fit accurately with the two pieces of the lapped effect.
Place the smaller piece of neatened fabric under the larger piece with the seam you have basted running in line with the finger pressed line marking.
Step 6 - Stitch
At this point, you will be sewing down either side of the seam line that has been basted together. The wider the distance you choose to sew from the basted seam the bigger the show of color from the slot.
If you have time to play around then sew a couple of samples using different widths. You will sew a straight stitch on either side of the basted seam. This stitch is sewn on the right side.
Sew your seam on either side of your basted seam. The width of the seam must not be wider than the slot fabric otherwise the fabric will not be caught in the seam. Sew a seam straight down each side and end off.
Step 7 - Remove Basting
Now you have completed the stitching it is time to remove the basting down the center. Take a seam ripper and gently remove the stitches or pull on the threads because you did not backstitch.
The seam down the center comes undone. It reveals the slotted fabric and the stitching down the side keeps it all in place.
Slot Seams - The Fast Way
If you don't need to be as precise with your seam allowance there is a quick and easy way to achieve the same look.
Step 1 - Finish
Finish the raw edges of the main fabric and the slot fabric.
Step 2 - Press
On the wrong side, press the over the seam allowances of the main pieces. Press the contrast in half to mark the center.
Step 3 - Align
All with right sides facing up, place the main pieces on top of the contrast slot. The edges of the main pieces should align with the center crease in the slot.
Step 4 - Stitch
Stitch down either side of the folded edges by ¼ inch (6mm). There is no unpicking needed with this method. The trick is to make sure the edges are aligned before you sew and use lots of pins so nothing moves as you sew.
Slot Seam - In Conclusion
The slot seam combines a decorative flash of color and at the same time strengthens the seam overall. It is a great seam for the side of hardwearing outdoor clothing. The show of color gives the garment a point of interest and sophistication. The slot seam can be used in all kinds of different situations to add that little bit of contrast or detail.