Join Bias Binding Without Making the Edge Bulky

Joining binding before it goes on a project lets you correct a twist while both strip ends are still accessible. Use one defined geometry rather than sewing any convenient diagonal across an overlap. The exercise here joins two square-ended bias strips at right angles, opens the join for inspection, then reduces the allowance before folding.

Start with two equal-width, unfolded bias strips cut from suitable lightweight woven fabric. For an original illustrative sample, make each two inches wide and about twelve inches long. These are practice dimensions, not a formula for every finished binding width. The ends must be square to the strips' long edges; a diagonal seam does not turn straight-grain material into bias.

Make the overlap easy to read

Lay strip A horizontally, right side up, with its length extending to the left and its square end on the right. Lay strip B right side down on that end, with its length extending downward. Their ends overlap in a two-inch square: B's square top end aligns with A's upper long edge, and B's right long edge aligns with A's right square end.

The two free lengths should make an L, pointing left and down. Smooth the overlap without stretching either strip. If both lengths point in the same direction, or the overlap is a rectangle instead of a square, rearrange the pieces before marking. This explicit setup is for square ends, not already angled strip ends.

Mark the correct diagonal

Look at the square overlap as it lies on the table. Draw the seam from its upper-left corner to its lower-right corner with a suitable temporary mark. Do not use the other diagonal, from upper-right to lower-left, which lies across the wrong side of the overlap for this join.

Andrie Designs' bias-strip lesson uses square ends, right sides together and a diagonal seam, then trims the allowance to a quarter inch and presses it open. SINGER's tutorial starts with angled ends. Its quarter-inch sewing allowance is not an instruction to sew a quarter inch away from the marked diagonal in this square-overlap exercise.

Sew the line and unfold before cutting

Hold the marked overlap with a suitable temporary method and sew directly along the diagonal, using the machine setup appropriate to the fabric. Remove pins before they reach the needle. Secure the ends as your machine permits without distorting the strip. The quarter-inch allowance will be established by trimming afterward; it is not measured inward from a square raw end now.

Remove the sample safely and unfold B away from A, leaving the surplus triangles attached for the moment. The right sides should face the same way along one continuous, equal-width strip. Look along both long edges while the cloth rests without tension. A step, narrowing or twist means the orientation or seam path needs correction before scissors remove the evidence.

An illustrative paper rehearsal makes the check visible without claiming a sewn test. Use two paper strips with the same square-end arrangement, mark the diagonal and fold the second strip over that line as though opening a seam. Their long edges should continue into one another. Paper checks orientation only; it cannot predict a fabric's stretch or folded thickness.

Trim the surplus, then spread the allowance

Once the opened alignment is correct, return the overlap to its sewn position. Cut away the surplus corner on the upper-right side of the seam, leaving a quarter inch measured perpendicular to the stitches. Keep both layers and the stitch line visible. You are removing the small triangular excess, not shortening either long strip. Do not cut into the stitching.

Open the join again and separate its two allowances, one to each side of the seam. Press them open within the fabric's care limits, lifting and placing the iron rather than dragging the bias length. Remove projecting little tips at the long edges without cutting the usable strip narrower. Let the sample rest before checking its width again.

Check the join in its folded form

For this sample, fold both long raw edges toward the center, then fold lengthwise once more so those edges are enclosed. Arrange the joined section around a straight scrap edge and compare its thickness with an unjoined section. Do not stretch it tight to hide a lump. This is a folding assessment, not a complete binding-attachment lesson.

On a real project, use the specified strip width, folds and application seam. Position joins away from avoidable intersections with other thick seams, allowing the required finishing length. Closing two tails already sewn around an edge is a different operation. This exercise ends with a straight joined strip whose allowance remains manageable after folding.