Boning
The strips that give corsets and fitted bodices their structure - spiral steel, flat steel, synthetic whalebone and Rigilene compared, sizes, buying pre-cut or by the metre, and capping the ends.
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Boning is the general name for the narrow, stiff strips inserted into channels in corsets, strapless bodices, and other fitted garments to stop the fabric between them from wrinkling or collapsing. The name is a leftover from the 18th and 19th centuries, when the material was usually baleen ("whalebone"): the flexible, horn-like keratin plates that some whales use to filter food. It wasn't actually bone, and it was replaced by steel and later plastics as whaling declined.
How to plan and sew boning channels is covered in Boning a Bodice. This page is about the materials themselves.
The main types
Spiral steel boning is made of two flat steel wires coiled into a flattened spiral. It flexes in every direction, including sideways, so it follows curved seams such as princess lines and the side seams of a corset. It's the standard choice for most bones in a corset or a well-structured strapless bodice. It comes in widths such as 1/4" (7 mm) and 3/8" (10 mm), and in different weights.
Flat steel boning is a flat strip of spring steel, usually coated to prevent rust. It bends in only one direction (front to back) and stays rigid edgeways. It's used where the garment should be straight and firm: either side of a centre back lacing or zip, at the centre front, and for the busk area of a corset. It comes in several widths and stiffnesses.
Synthetic whalebone (also called plastic or polyester boning, or "German plastic") is a solid flexible plastic strip. It's lighter than steel and cheaper, and it can be cut with heavy scissors and filed smooth. It's good for moderate support in evening wear and costume. The cheaper, thinner kinds can soften with body heat and take a permanent bend over time, so they aren't suitable for a corset that does real shaping.
Rigilene is a woven polyester boning: fine polyester rods held together by woven threads. You can sew straight through it, so no channel is needed, which makes it quick and popular for lightweight bodices. It gives light support only, and it kinks and leaves visible bumps if bent sharply or used for too much shaping. Seal the cut ends by melting them carefully with a flame, or cover them with a fabric scrap.
Busks are a front-opening corset fastening: two flat steel bones, one with loops and one with studs, that hook together down the centre front. They're specific to corsetry.
Choosing boning
| Garment | Suggested boning |
|---|---|
| Corset | Spiral steel on curved seams, flat steel at the back and busk |
| Strapless evening or bridal bodice | Spiral steel on curves, flat steel or synthetic whalebone at the back |
| Bodice with straps, light support | Synthetic whalebone or Rigilene |
| Costume or short-wear pieces | Synthetic whalebone, or cable ties for a very low budget |
Buying and cutting
Steel boning is sold either pre-cut to standard lengths with the end tips already fitted, or by the metre to cut yourself. Pre-cut is easier and gives cleaner ends, so measure your channels and buy the nearest lengths, about 1/4"-1/2" (6-13 mm) shorter than each channel at each end.
To cut spiral steel yourself, use heavy wire cutters (ordinary scissors won't cut it). Then crimp a metal U-shaped end tip over the cut end with pliers. Flat steel needs heavy-duty cutters or a hacksaw, and the cut corners must be rounded off with a file and capped, or dipped in a protective coating ("tipping fluid").
Finishing the ends
Every cut end needs finishing, whatever the material. A raw end of steel or plastic will work its way through the channel and the outer fabric, and eventually into the wearer:
- Spiral steel: crimp on a metal end cap.
- Flat steel: round the corners with a file and cap or dip the ends.
- Synthetic whalebone: round the corners with a file or nail file, and optionally cover with a dab of glue or a little tape.
- Rigilene: melt the ends lightly, or fold a scrap of fabric over them and stitch it in place.
Care
Steel bones can rust if the garment is washed or worn in damp conditions. Where channels allow, remove the bones before washing and dry them thoroughly. Garments with sewn-in bones are usually best spot-cleaned or dry-cleaned.