Bias tape (or Bias binding) as a great way to finish a neckline when your fabric is delicate (like a silk or polyester chiffon). Neck facings don't sit as well with such delicate fabrics.
Bias tape is a piece of fabric cut on the cross grain (cutting a line at 45 degrees against the warp and weft threads of a woven fabric). Fabric that is cut on the bias "moves" with the cross grain (and therefore folds around corners), unlike a fabric cut parallel with the grain line on a woven fabric which is rigid in structure..
A. You can purchase pre-made bias tape, and for delicate fabrics you will need to ensure your bias tape is made from a light weigh satin. Cotton bias should be reserved for stiffer fabrics. Alternatively you can make your own - it is not too difficult.
B. To make your own bias tape you need to cut your piece of fabric at a 45 degree angle on the cross grain. You can use a "bias tape tool" but this is not essential (and is more useful for stiffer fabrics like cotton than delicate fabrics like a silk or polyester chiffon). I recommend the following method when making bias tape for use on delicate fabric:
In this image the fabric was not a square - I used the scraps left over from the garment.
- Fold your fabric so that the fold line is at 45 degrees across the warp and weft threads. For example, if your fabric is cut in a square, put your finger on the bottom left hand corner and using your right hand, bring the RHS bottom corner up to meet the top LHS corner so, what was the bottom edge is now aligned with the left hand edge.
- Press the folded edge
- Mark a line that is twice the finished width you desire plus a small seam allowance. If you want your finished bias edge to be 1cm, you will need to cut a strip that is 3cm wide (on the fold). If you are comfortable sewing a 0.5cm seam then cut your fabric at 2.5cm wide (on the fold).
ATTACHING THE BIAS TO THE NECKLINE:
Once completed, the bias tape will have a neatly finished edge on both the inside and outside of the garment. It is personal preference whether you sew the bias tape first on the outside and fold inward, or visa versa. Because the final top stitching is likely to show (unless you are extremely accurate and can sew "in the ditch" all the way around the neckline) I recommend the following:
1. With the bias tape right side out and folded in half lengthway, pin & sew it to the inside (wrong side) of the neckline of your garment. Align the raw edges.