Does your costume have contrast trim around the edges? Never fear — bias tape isn’t as scary as it looks! This is a very beginner-friendly guide to double-fold bias tape application.
This is double-fold bias tape. If you unfold it, you will see three fold lines. (This is the kind I recommend for trimming the edges of a garment.) If you are using single-fold bias tape, you will see only two fold lines, and you will have to use your imagination or a ruler to divide the wide center section in half in order for it to wrap both sides of your fabric.
Lay your bias tape flat and find the side that is slightly narrower than the other. You will want to put the narrower side toward the edge of the fabric in the next step.
Lay your piece out so the front/outside/side that will be seen most frequently is facing you. Unfold the narrower half of the bias tape and line it up exactly along the edge of your fabric. Pin bias tape to fabric with right sides together. (I recommend doing this with the fabric laid out on a flat surface, so you don’t get any wrinkles or puckers from holding it.)
Carefully stitch right along the fold line that is closest to the edge. Precision is important here, so go slowly!
Once you have stitched along the fold, it should look something like this:
Next, fold the rest of the bias tape around the edge of the fabric. The raw edge of the tape should be folded underneath (as it’s pre-creased to do). If using double-fold bias tape, line it up neatly so the center fold line runs along the edge of the fabric. Pin it in place. If done correctly, the wider half of the bias tape should now be on the back side, and will extend a tiny fraction below the stitch line (or the front side, when viewed from the end). This placement is important, because the needle has to punch through the stitch line and catch the longer side of the fabric on the back!
This is the tricky part! With your piece facing front-side-up, stitch with the needle running right in the depression made by the previous stitching line. (This is known as “stitch in the ditch.”) Your needle should land right between the two colors of fabric. If you need to, you can hand-crank the sewing machine for extra precision. If your tape is positioned correctly, the needle will pick up the longer side of the bias tape on the back side.
Magic! The stitching is nearly invisible on the front, and only shows from the back. ? (If you want the stitching to be less visible on the back side, you can match your bobbin thread to the bias tape color, so it blends.)
Finally, press your edges out flat with an iron to make everything crisp and smooth.
Congratulations, you have conquered bias tape. Level up! *ding*
(Note: You can see a line of stitching and unfinished edges on the silver fabric I’m using for this demo. If you were adding bias tape around the edge of a finished garment, you would normally stitch the outer fabric and lining together, flip them right-side-out, and press out the seam to make it crisp before adding the bias tape. Since the piece I’m making here is just an epaulet and will have bias tape over the edges, I am eliminating the flipping/pressing steps by stitching the pieces together directly and hiding the seam under the bias tape. This also eliminates the extra seam allowance bulk. If you do this, make sure your stitching is close enough to the edge of the fabric that the bias tape will cover it!)