What are knife pleats?
Knife pleats are crisp, side-way pleats, with equal space from top to bottom. The pleats are all of one size vertically but widthwise one side (pleat width) is wider than the other (inner fold) because of which the pleats lay to the side. A knife pleat is sharp like the edge of a knife (When it is pressed properly).
On clothes, Knife pleats are usually placed in the right to left direction. It is usually made in one direction but can be made in both direction for visual interest.
Pleats are generally added to contain fullness and knife pleats does this perfectly. They are most commonly used in skirts. The knife pleats give a smooth line across the fabric.
Fabric needed for Knife pleats
Medium weight fabrics are the best to make knife pleats. Cotton, linen etc pleat very well.
You need to have extra fabric to sew pleats – and for a full plaited knife pleats it works out like this – Take double the fabric ; ie. 2″ of fabric will result in a 1″ finished knife pleat. ie double the fabric is needed. You can also make shallow plaited knife pleats and this will need lesser fabric and will give lesser fullness.
How to sew knife pleats
If you already have a pattern for knife pleats, keep it on the fabric and then press the fold lines. You can then use these as guidelines to make your knife pleats. Or you can use tracing paper to transfer the pattern lines for the folds.
Otherwise, mark the pattern for the knife pleats this way.
Mark three lines for each pleat. Remember you are pleating from right to left. The first part is the front of the fold; the next line is the roll line, then the inner fold line, and the next line is the placement line.
If A= 1: ; 2A= 2″. 2 A is the front of the pleat.
Fold the fabric by the roll line and this should meet the placement line.
Press the knife pleats that you have folded this way.
Use basting stitches to keep the knife pleats in place.
You can leave the pleats unstitched (ie stitched only at the top edge) or partially sew along the edge, and leave the rest open to release the pleat.
If you are edge stitching, you will be stitching along the edge of the folds a little distance to contain the fullness. Mark where you want the knife pleats stitched. On skirts it is usually marked till hip level.
Edge stitch along the fold till where you have marked.