Sprung or Spiral Steel Boned?
The main difference between sprung (the flat strips) and spiral steel (the wire wound tightly into strips) is their bend-ability, but which type of steel bones will suit you and your corset? Here I go into the different properties of the two main types of corset boning so you can decide on the type of steel boned corset you want to make or make better choices about your bone placement. FYI for other articles on making corsets, feel free to browse my How To Make Corsets page.
Why Steel Bones Are Better Than Plastic
You may already know about the perils of using plastic over steel bones to make a corset but incase you don’t here’s a quick explanation – Unlike plastic that weakens if it bends too much, steels can bend a great deal further without developing weak points and kinks. This is great as the body needs to bend and stretch during everyday activities. A corset training corset needs to be robust and allow for this movement as it is worn for 8 hours plus a day.
The Difference between Sprung And Spiral Steel Bones
Both steel types are springy enough for everyday corset training but spiral steel bones will give more movement as they bend a lot easier than their solid counterparts which like to spring back into their original position, hence the name ‘sprung steel bones’.
Spiral steels can also bend in directions the solid steels can’t. Spiral steel will bend sideways and can also twist, which means it’s the only type you can use for boning corsets diagonally across curves (for example across the waist and over the curve of the hip). Something to consider when designing corsets. The creative bone placements you see on high end corsets are normally done with thin 5mm spiral steels which puts up little resistance but is great for boning whole panels or panel sections. I recently boned a whole bodice with a few hundred of these.
On the right is a flat steel bone, also known as sprung steel. It’s quite rigid and only bends a little. It does not bend sideways at all. In terms of bone placement, this is why you have to use flat steels in the back of your corset, to keep your eyelets straight when you tighten your laces. Spiral steels would bow and we don’t want that!
Everywhere else you can use either the spiral or the flat bones – it’s personal choice. However, makers will often use a mix, with the spiral going in a few of the side seams for ease of movement.
So if you need more support for say plus sized corsets or back support; use sprung steel bones. If your priority is freedom of movement, eg you lead an active lifestyle or you’re making a corset for an inexperienced corset wearer who won’t be used to the restrictive garment, opt for spiral steel boning.