I wrote this a decade or so ago, originally for a post to a discussion list, later re-written for my old website. This is installment 2 of the bits and bobs coming over here from over there.
First, for clarity and beacuse the two are often confused:
- Interfacing: A supplemetary layer of fabric, normally placed between the fashion fabric and the lining, or between the fashion fabric and the facing. It is intended to help stiffen or strengthen the fashion garment. In fully lined garments (such as jackets), all stress points may be interfaced, sometimes severaly layers deep, to help the garment keep its designed shape.
- Facing: A shaped piece of fabric intended to finish a garment edge, often cut as an abbreviated version of the garment piece it matches. This is seamed along the garment edge, turned and either finished and left loose inside, or sometimes sewn down either inside or outside, depending on the design of the garment.
In modern clothing the facing is often only attached at the garment edge (collar, cuff, placket, hem, etc) and is left to hang loose inside the garment. These loose facings are often interfaced to keep them from crumpling, flopping, or slipping out of the garment edge. Which they always do anyway. Personally, I hate these and I sew them down invisibly inside my garments.
In some eras of period costume, facings are used as a decorative motif, and are often embroidered. They serve a dual purpose, in that they are both a finishing technique (practical) and a form of ornament (decorative). Where facings are used as a decoration, additional fabric bands may also be applied to continue the ornamental theme across the garment. I do 12thc, and therfore I make use of this decorative technique, and I find that I almost never have to interface my applied facings, *unless* it is a fine or unstable fabric.
On fastening keyhole necklines
I have often been asked how one should fasten a keyhole neckline. The simple, documentably period answer? A brooch.
Author's note: Small brooches are also really useful on regular clothing as well as medieval period clothing. They are also a really nice fashion detail. Every time I've worn a period-costume jewellry item with my everyday clothes, I've been complimented on it.
Medium-sized annular (unbroken ring) brooches with a hook catch on the back to anchor the pin seem to work well, as well as simpler ring- or disc-brooches. It takes a bit of practice to use a pen-annular (broken
ring) brooch to close the corners of a keyhole neckline, but it can be done.
You only need to close up a keyhole neckline if it's cold enough to, or if decency calls for it. If the corners of the neckline like to fly open and you don't want adventurous people looking down the inside of your tunic, pin them together. If you don't want to have to pin them, apply a trim or decorative facing that is fairly stiff.
This type of neck-finish was fashionable in various areas for hundreds of years. Generally speaking, the period way will turn out to be the most practical way, IME. If you are curious about exactly what is right for your persona, look at illuminations and period art for help.