Tutorial: How to perfectly fit bias tape to an armhole or neckline

bias tape finished top

Inside (left) and outside of top finished with bias tape facing.

During the construction of my Sorbetto top I suddenly realised how I can guarantee that bias tape will fit perfectly in any armhole or neckline (or any other place where the beginning and end of bias tape meets such as bag tops, hems and quilts). Until now I was somewhat mystified by how to do this properly and usually managed to fit it by a process of trial and error. Not anymore! It turned out to be very easy and since I am guessing that I am not the only one who could do with some clarification on this topic I thought I’d share my newfound knowledge in my first tutorial.

I prefer to match up two ends of bias tape with a seam that is at a 45 degree angle with the length of the tape instead of a 90 degree angle.  A huge advantage of having a seam that is at a 45 degree angle is that it will create much less bulk when the tape is attached to the project, especially when the bias tape is used to encase a fabric edge. I also think that a 45 degree angle seam will be more stable because this seam will run parallel to the grain line of the fabric since the fabric from which bias tape is made is cut on the bias.

The problem though with the 45 degree angle is where exactly to sew this seam to ensure that the tape will fit your opening perfectly and this is what I am now able to explain to you. I figured it out while trying to apply a method for attaching a binding to a quilt to the neckline of the Sorbetto and failing miserably. The bias tape turned out much too long. Then in a true light bulb moment I realised that for the quilt binding I had to add 5 cm (2’’) to the length of the binding at a certain point because the unfolded binding strip was 5 cm wide. The fabric strip I used to make my own bias tape for the neckline was only 2.5 cm (1’’) wide so that is why I ended up with a much too long strip to fit my neckline. When I added 2.5 cm instead of 5 cm my bias tape suddenly fit perfectly!

How to match up two ends of bias tape to sew the 45 degree angle seam.

I made another Sorbetto to demonstrate two methods for creating perfectly fitting bias tape. In sewing there are usually several ways to the same end result and it’s up to you to figure out which method works best for you. For the top in this tutorial I used bias tape to create a facing on the inside of the garment, but these methods can also be used to create an outside facing or for encasing a fabric edge in bias tape (which I think is what bias tape is used for most often). Please note that this tutorial is only to be used with woven fabrics. When attaching stretch bias tape to knit fabrics other rules apply.

Method 1: “Leave a gap”

Step 1.1: Make your own bias tape or get a piece of store bought tape that is a little longer than the opening you want to attach it to. If this is the first time you are attaching bias tape to an opening I suggest that you make it at least 10 cm (4’’) longer.

Step 1.2: Pin the bias tape to the opening, leaving the ends of the tape trailing off. I try to make sure that the place where the seam will end up is in a spot where it is hardly noticeable, such as under the arm when attaching the tape to an armhole or near the shoulder seam when attaching it to a neckline. I wouldn’t match it up exactly with another seam though as this will create unnecessary bulk.

Step 1.3: Stitch the bias tape to the opening leaving approximately a 10 cm/4’’ gap between the start and finish of your stitch line. Backstitch a couple of stitches at the beginning and end to secure.

Step 1.2 and 1.3.

Step 1.4: Cut off the left end of the bias tape so that the end stops in the centre of the gap. This is not something that you need to measure accurately but your cut should be straight.

Step 1.4

Step 1.5: Align the right end of the bias tape with the gap. It might be helpful to use some pins to secure the tape if the opening is very curvy.

Step 1.6: Fold the left end of the bias tape over the right end. Mark on the right end of the tape where the left end stops. This is something that you do want to do accurately.

step 1.6

Step 1.7: Now it is time to add enough length to the right end of the bias tape to be able to sew the 45 degree angle seem. The amount that needs to be added is the unfolded width of the bias tape. In my case this is 2.5 cm (1’’). Use a ruler (or a piece of the unfolded bias tape) to measure this distance on the bias tape. Draw a line across the bias tape to indicate where this measurement stops.

Step 1.7

Step 1.8: Cut off the right end of the bias tape on the second marking that you made.

Step 1.8

Step 1.9: Match up the edges of the bias tape as indicated in the picture and sew the two ends together as shown. It can be helpful to draw the line that you want to stitch with chalk or disappearing marker so you can sew on the line. After sewing the seam check whether you didn’t accidently twist the bias tape. Press the seam open and trim the seam allowances.

sew bias tape together

Step 1.9

Step 1.10: Pin the bias tape to the gap and stitch in place.

Step 1.11: Fold the tape over to the other side and edge stitch in place.

biastape8

Step 1.10 and 1.11

You are done and should now have a lovely looking bias tape bound opening!

Bias tape finished armhole!

Method 2: “Create a circle”

Step 2. 1: Carefully measure your armhole or neckline and write down the measurement. This step is very important, if you do not do this accurately you run the risk that your bias tape will not fit as perfectly as you hoped it would! For the top that I used for this tutorial the neckline measured 75 cm.

Step 2.2: To the measurement from step 1 add the width of your unfolded fabric strip or store bought bias tape. Write down this measurement as well. I my example I used 12 mm (1/2’’) bias tape, which was made from a 2.5 cm (1 inch) wide strip. So I added 2.5 cm to my measurement from step 1, which was 75 cm and ended up with a total of 77.5 cm.

Step 2.3: Make your own bias tape or use store bought tape. Cut it exactly to the measurement that you wrote down in step 2. Do, however, slightly stretch the bias tape when you measure it. It has some stretch due to being cut on the bias and if you don’t stretch it out just a little bit, it might end up too long when you fit it into the opening.

Step 2.4: Now it is time to create a circle with your bias tape. Match up the edges of the tape as shown in the picture and sew the two pieces together as indicated. Check whether you didn’t accidently twist the tape and ended up with a Möbius strip, which will be impossible to attach to the opening (this, of course, totally didn’t happen to me…).  Press the seam open and trim the seam allowances.

create a bias tape circle

Step 2.4: The careful observer will notice that this is not the actual piece of bias tape that was used to face the neckline. I didn’t think my original picture was clear enough so I took another one with a shorter piece of bias tape.

Step 2.5: Pin your bias tape to the opening and sew it in place.

Step 2.5

Step 2.6: Fold the tape over to the other side of the garment and edge stitch in place.

Step 2.6

You are done and should now have a lovely looking bias tape bound opening!

Bias tape finished neckline!

I would love to hear from you whether you found this tutorial useful and which method is your favourite! Also, if you have any questions don’t hesitate to ask and I’ll do my best to help you.