Understanding What Bias Tape Is and Why It's Used
Bias tape is a strip of fabric cut at a 45-degree angle to the grain of the material. This diagonal cutting creates fabric that stretches and curves smoothly, making it ideal for finishing edges on garments and quilts. The word "bias" refers to this diagonal direction across the weave of fabric.
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Most bias tape is folded in half lengthwise with finished edges, creating a strip that's ready to attach to fabric edges. Standard bias tape width ranges from one-half inch to two inches, though one-half inch and five-eighths inch are the most common sizes for general sewing projects. The tape comes in various fabric types including cotton, polyester blends, and specialty materials like lace or metallic finishes.
Bias tape serves several practical purposes in sewing. It provides a clean, professional finish to raw fabric edges that would otherwise fray over time. Unlike straight grain binding, bias tape's diagonal construction allows it to stretch around curves without puckering or wrinkling. This makes it particularly valuable for finishing armholes, necklines, and curved edges on garments. On quilts, bias tape binding creates durable edges that withstand washing and use over many years.
The history of bias tape binding in sewing dates back over a century. Before pre-made bias tape became commercially available in the mid-20th century, sewers had to cut and fold their own strips from fabric scraps. Today's pre-made options save significant time while maintaining the same professional appearance.
Practical takeaway: Purchase bias tape that matches your project's color and fabric type. For curved edges, choose narrower tape (one-half inch) to reduce bulk. For straight edges on quilts, standard five-eighths inch tape works well. Consider buying slightly more tape than your measurement suggests to account for overlapping seams and practice.
Preparing Your Fabric Edge Before Applying Bias Tape
Proper preparation of the fabric edge is essential for successful bias tape binding. The first step involves trimming any excess fabric or loose threads from the edge you'll be binding. Most garments and quilts have slightly uneven edges after cutting, so a straight edge is worth taking time to achieve.
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For garment projects, try on the item if possible before binding the edges. This allows you to check the fit and positioning. For example, when binding an armhole, put the garment on and mark where the binding should sit relative to your arm. This prevents having to remove and reapply binding later.
Curved edges require special attention before tape application. Press a steam or dry iron over the curved edge to relax the fabric slightly. This makes the edge lie flatter and reduces the tension when you're pulling the binding around the curve. For necklines and armholes, you may want to stay-stitch (sew a line of stitching one-quarter inch from the raw edge) before binding. This reinforces the edge and prevents stretching during the binding process.
For quilts, square up and trim all edges straight before beginning the binding process. Use a large square ruler and rotary cutter to ensure corners are 90-degree angles. Measure across the width and length of the quilt at multiple points—top, middle, and bottom—to confirm even dimensions. Square quilts accept bias tape binding much more smoothly than irregular ones.
Consider the layout of your binding seams. Plan where tape seams will fall, avoiding placing them at prominent locations like center front closures or quilt corners. Mark these locations lightly with a fabric pencil or chalk if needed.
Practical takeaway: Spend 10-15 minutes preparing edges before opening the bias tape. Use sharp fabric scissors or a rotary cutter for clean cuts. Press curved edges with steam to relax tension. These steps reduce frustration during the binding process and produce noticeably neater final results.
Methods for Attaching Bias Tape to Fabric Edges
There are two primary methods for applying bias tape: the single-fold method and the double-fold method. Each has different applications and produces slightly different finished appearances.
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The single-fold method uses bias tape that's folded only once, leaving one edge slightly wider than the other. You open the fold slightly, place the narrower edge against the fabric edge, and sew through both layers. Then you fold the wider back edge over to the reverse side and stitch it down by hand or machine. This method works well for items where the back of the binding won't be heavily visible, like the inside of garments or the back of quilts.
The double-fold method, also called French binding, uses pre-folded bias tape with both edges already folded toward the center. When opened partially, the tape wraps around the fabric edge symmetrically. This creates a balanced, professional appearance on both the front and back. Double-fold bias tape is the industry standard for quilts and garments that will see regular use or washing.
For machine application, the standard approach involves three steps. First, open out one fold of the bias tape and pin it to the right side of your fabric edge with the raw edge of the tape aligned with the raw edge of the fabric. Using a thread color that matches the tape, sew along the existing fold line of the tape, typically one-quarter inch from the edge. Use a stitch length of 2.0 to 2.5 millimeters for strength without creating visible holes.
Second, fold the tape to the wrong side of the fabric, wrapping it around the edge smoothly. The fold should sit just past your machine stitching line. Pin or use clips to hold it in place. The back edge should cover your machine stitching.
Third, stitch the back edge down. This can be done by machine using a narrow zigzag stitch that catches the back fold, or by hand using a ladder stitch for an invisible finish. Hand stitching takes longer but produces the least visible seams.
Practical takeaway: Choose double-fold pre-made bias tape for most projects unless you have specific reasons to use single-fold. Practice on a scrap of fabric first to understand the technique. Machine stitching the back takes 20-30 minutes for a typical quilt and produces adequate results for most purposes. Reserve hand stitching for show items where seams should be invisible.
Managing Curves, Corners, and Challenges
Binding curves and corners presents the main challenges in bias tape application. Fortunately, the bias nature of the tape makes curves easier to manage than many sewers expect. The stretch in the bias tape allows it to ease around gradual curves without creating puckers or wrinkles.
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When binding an outward curve, such as the bottom edge of a flared skirt or the outer edge of a rounded quilt corner, the bias tape naturally spreads slightly as you sew. Apply even pressure without pulling the tape tight. If you pull too hard, the edge will curve upward and look wavy. If you don't hold it taut enough, it will bunch. The goal is gentle, even tension that lets the tape's built-in stretch do the work.
Inward curves, like armholes and necklines, require the tape to gather slightly. Sew slowly around these curves and gently ease the tape into the curve as you go. Some sewers make small clips into the seam allowance (cutting one-quarter inch into the seam allowance at one-inch intervals) to help the tape lay flat, though this isn't always necessary with quality bias tape.
Corners present a different challenge. For outside square corners (like the corners of a rectangular quilt), fold the tape at a 45-degree angle at the corner, creating a diagonal fold. Sew right up to the corner, then fold the tape at that angle. This creates a neat mitered corner. Some stitching may need to be reinforced by sewing back over the corner area once or twice to ensure durability.
For inside square corners (rare in most projects), clip carefully into the seam allowance of the fabric at the corner point. This allows the tape to fold smoothly around the inside angle without bunching.
Common mistakes include pulling the tape too tightly, which creates wavy edges; insufficient pinning before sewing, which leads to shifting; and stopping the stitching line too far from the edge, allowing the tape to separate from the fabric during use. Most mistakes can be avoided by pinning thoroughly every two to three inches and sewing at a consistent distance from the fold