Casing

What is casing in terms of sewing?
A casing is a type of hem but, it encloses the elastic or drawstring.

What is the purpose of a casing?
In dressmaking, elastic or drawstrings are used to provide fullness and control over the fall of a garment be it the neckline (typically part of the design) or the waistband (to provide a perfect fit despite slight increase or decrease in waistline). Casings are used to enclose them.

Where is it used?
Neckline or bottom of blouses, the waistband or bottom of pants or pyjamas, sleeve cuffs, curtains (to insert curtain rods) etc.

Types of casing

1. Fold down casing - is more commonly used. It is just a hem that accommodates the drawstring or elastic inside it.
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3. Applied casing - usually at the waist. A separate piece of fabric is used to make the casing either on the inside or the outside of the garment. The purpose is to allow the wearer to adjust the fit of the garment.

Resources:

1. Casing
2. Simplicity - Shortcut Sewing
3. Reader's Digest Complete Guide to Needlework