Bra Making Basics: Wire Play vs Wire Spring Posted on 30 Dec 13:19 , 0 comments

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Just a quick post today to clear up a couple of bra making terms that can be confusing. Wire play versus wire spring. I see these terms used interchangeably but they are two different concepts both related to the underwire.


Wire play is the amount of room you would add to each end of the wire line where the channeling is sewn into to allow room for the wire to move back and forth inside the channel. Too much or too little wire play can cause your wire to start poking a hole in the underwire channeling. Ouch! To prevent that it is standard to at 5mm at each end of the wire plus 3mm for bartack sinkage. A grand total of 16mm (8mm at each end).

Wire spring is how much the wire will “spring” open from it’s relaxed state when worn. Wire spring is what allows the wire to fit to the natural breast root. You want the wire to be able to spring open rather than having a wire that is exactly the same shape as the breast root. The bra also gains it’s cantilever effect from some tension being placed on the wire. Not enough spring may mean the wire will poke at the underarm or some support will be lost by the lack of tension placed on the wire. Too much wire spring will force the wire into a S shape poking you in either the arm or the sternum.

How much is the correct amount of spring? Well there is no one rule and it does depend on the wire. For a standard shape core size in a 20/22 15mm wire spring is common. However plus sizes may spring up to double that amount. Sometimes wire spring is added to the pattern at both the center front and at the arm. Wire spring is a complicated subject. You need some but not too much.

As you can see the typical amount of wire play and wire spring is very similar so it’s easy to get confused. Just remember that wire play is added so the wire can move vertically and wire spring is added so the wire can move horizontally.