This page is meant to teach you all about Diagonal Seam Tape. Scroll down to find out what it is, the uses, and why I love it.
Diagonal Seam Tape can be purchased here. For wholesale inquiries, please email me.
Also if you have any questions, please email me at firstname.lastname@example.org. Thank you! -Allison
Want a printable summary of these instructions? Click on this link to find a printable summary!
You can also find a great video of how to use it by my friend Sherry here (click here).
What is Diagonal Seam Tape?
Diagonal Seam Tape is simply washi tape that is placed on the front plate of your sewing machine to act as a guide while you are sewing diagonal seams.
The tape is strong, thin, sticks well to almost any surface, and comes off easily. Each roll has 10 yards of tape so it should last a really long time.
The red line in the center is aligned with the needle of your machine, and the black lines on either side are 1/4″ to each side from the center of the lines, to represent a 1/4″ seam allowance. The black lines won’t replace a piecing foot with a perfect 1/4″, but act as an extra guide.
The tape removes cleanly, but I recommend removing or replacing the tape often or after each project to avoid any residue on your machine. This tape is not meant to be a permanent fixture on the machine, and long term use without replacement may result in some residue to clean off.
How to place the seam tape on the machine:
Every machine is a bit different, so there are examples below on two different machines. Scroll down through the photos for more info. You can also see examples of how it’s placed on different machines under the Instagram #diagonalseamtape hashtag here.
Cut the tape to make a straight edge, and place the edge of the tape directly in front of the feed dogs of the machine.
Align the red line up with the needle. You can use a ruler to make sure it’s lined up, but I find it easy to eyeball it.
The machine I’m using in this photo is a Juki, and you can see from the photos that the 1/4″ mark on the metal plate is not even close to accurate. It’s at least 1/16″ larger than 1/4″. The black line of the seam tape is exactly 1/4″, and it’s so nice to finally have a good 1/4″ seam allowance reference on this machine!
You can eyeball the tape straight (I do this most of the time), and you can also take a small quilting ruler and line it up with the edge of your presser foot or lines on the metal plate, and just double check that the tape is straight. Especially on this machine the markings and presser foot are not straight on my machine, so in this case eyeballing it and using a ruler as a general guide works best. Don’t worry if you can’t get it absolutely perfect, your seams should still be just fine.
Placing the tape on my Bernina is much easier because the markings on the machine are accurate.
Place the tape at the edge of the feed dogs, and you can see here that I line the red line up with the needle, and there are two little 1/4″ marks on the metal plate that match up perfectly with the center of each black line. Perfect 1/4″!
It should be straight if you line it up with both marks, but you can double check with a ruler against the foot.
Now you are ready to sew with it!!
Removing Diagonal Seam Tape:
The tape removes cleanly, but I recommend removing or replacing the tape often or after each project to avoid any residue on your machine, especially in high temperatures. If you find the tape as left a little residue on your machine, use a washcloth with warm water, or a gentle cleaner or coconut oil to remove it.
Uses for Diagonal Seam Tape:
You can use Diagonal Seam Tape anywhere in a pattern that calls for a diagonal seam, or anywhere it asks you to “draw a pencil line or diagonal line from corner to corner on the square”. Anywhere you would draw a pencil line, you can use diagonal seam tape to save so much time! Below are just a few examples of the uses of this tape, but there are many more! I have a long list of my own patterns where Diagonal Seam Tape works perfect, but a few of my favorites are Chickens, Trellis, Shimmer, Layer Cake Bounce, Batter Up, One Way, Pumpkins, Modern Table Runners, Playful 2, Tahoe, and many more. Anywhere you see any type of diagonal seam, you should be able to use this tape.
Making a flying geese block:
Place the square in the corner of the strip and line up the edges as you normally would, without drawing the diagonal pencil line first. Line the top corner of the square up with the red line, that’s where you will start sewing. Line up the bottom corner of the square on the red line. Start sewing at the top corner, while keeping the bottom corner of the square on the red line the entire time. When you get to the very end and run out of tape, just sew to the corner of the square. You will get very fast at this after doing it more!
Now you’ve sewn a diagonal line! Trim the edge leaving 1/4″ as you normally would, press the corner out, and repeat with another square in the adjacent side of the strip. Start sewing in one corner (either corner is fine) and keep the opposite corner on the red line the entire time you sew. Trim the corner leaving 1/4″, and press the seam. You have a flying geese block without ever marking lines or using a special ruler!
Adding Triangle Corners to a Block (a Snowball Block):
Place a smaller square in the corner of a larger square, with the point of the small square at the needle. Start sewing, continuously keeping the bottom point of the small square on the red line until you reach the other point. Trim the corner leaving 1/4″ seam allowance, and press. Repeat on the other 3 corners to make a snowball quilt block.
Here is a quick Instagram video I made to show using this method to make a Heart Block (heart block pattern found here):
To Make 2 Half Square Triangles:
The size of HST’s you can make using this method depends on the size of the machine table in front of your needle. I can make 4 1/2″ HST’s using this method on my Juki, but only 3 1/2″ HST’s on my Bernina. Place a square on your machine on the diagonal to see how big you can go!
Place your two same sized squares together, and align the top point of the squares 1/4″ to the right of the needle (or the edge of your presser foot if using a 1/4″ foot). Align the bottom point of the squares on the right black line. Sew, keeping the bottom point on the black line the whole time until the end.
Now do the same on the other side of the point, align the top point 1/4″ to the left of the needle at the top (or edge of presser foot), and the bottom point on the left black line. Sew the line, cut in between the two seams, and press to make 2 HST’s with no marking!
With the accurate 1/4″ lines on the tape, sewing long strips and strip piecing is especially easy and accurate. Since the 1/4″ markings aren’t accurate on my Juki machine, this tape has been an amazing addition to my sewing. I can see where the 1/4″ line is and line up my fabric as I sew (and I like to sew fast!).
It’s also a great way to help kids or beginners learn to sew because they have a visible line to help them sew a straight and with a 1/4″ allowance.
There are so many more uses for Diagonal Seam Tape, I could go on and on. I’ve been using it for a few months and it’s been an amazing addition to my machine and speeding up sewing, and it also looks good enough to keep on my machine.
I hope you love it as much as I have, and as always please email me with any questions at email@example.com
Happy quilting! -Allison