Bra Underwires – Nylon-Coated and Galvanized, Sizes 75–110

What Is a Bra Underwire?

A bra underwire is a shaped support wire placed inside the lower cup channel of a bra or structured garment. It helps the cup follow its intended silhouette, supports the lower cup area and stabilizes the design around the underbust line.

Underwires are used not only in bras, but also in bikinis, swimwear, corsets, bustiers, stage garments and other fitted pieces that require a shaped cup construction. The correct wire must follow the pattern line of the cup; choosing by the size number alone is not enough.

Underwire Types in This Category

• Nylon-coated bra underwires: Metal-core underwires with a smooth plastic outer coating.
• Galvanized bra underwires: Underwires made with galvanized metal wire construction.
• Size range 75–110: A practical series for different cup patterns, wire lines and structured lingerie designs.

Nylon-Coated vs. Galvanized Bra Underwires

Nylon-coated underwires have a metal supporting core with a plastic outer layer. The outer coating gives the wire a smoother surface for use inside a fabric underwire channel. This construction is commonly selected for bras, lined swimwear, bikinis, corsets and fitted lingerie projects.

Galvanized underwires use galvanized metal wire. The best choice depends on the garment construction, channel fabric, lining thickness, intended use and the finish required by the design. Even when two wires belong to the same size series, the outer surface and production handling can differ between nylon-coated and galvanized options.

How to Select the Correct Bra Underwire

A size marking such as 75, 80 or 90 is only the starting point. A good fit depends on the relationship between the underwire and the cup pattern. The wire should follow the cup seam line without being too short, too long, too flat or too deep for the design.

Reference Dimensions: Size 75 Nylon-Coated Bra Underwire

These dimensions are a reference for the size 75 nylon-coated option only. The wire contour, width and depth change across the size range. For production work, the selected underwire should be tested against the actual cup pattern before bulk sewing begins.

Typical Uses of Bra Underwires

• Underwired bras and structured lingerie
• Bikini and swimwear tops
• Corsets and bustiers
• Fitted eveningwear and stage costumes
• Custom lingerie and shaped cup designs

Common Selection Mistakes

• Selecting a wire only by the printed size number
• Ignoring the wire contour of the cup pattern
• Using a wire that is too wide, too narrow, too shallow or too deep
• Choosing the wire before confirming the underwire-channel dimensions
• Leaving the wire ends insufficiently protected inside the garment construction
• Confusing a 50-piece pack with 50 matching pairs

Buying Checklist

• Measure the lower wire line of the cup pattern.
• Check inner width and depth as well as the size designation.
• Select nylon-coated or galvanized construction according to the garment build.
• Confirm the underwire channel width and lining structure.
• Decide whether the wire will be used in a bra, swimwear top, corset or bustier.
• Remember that each pack contains 50 pieces, equal to 25 pairs.
• Make a sewn sample before full production.

Frequently Asked Questions

What does a bra underwire do?

A bra underwire supports the lower cup structure and helps the cup maintain its intended contour around the underbust area.

What is the difference between nylon-coated and galvanized underwires?

Nylon-coated underwires have a metal core with a plastic outer finish. Galvanized models use galvanized metal wire. The appropriate option depends on the garment construction and underwire channel.

Does size 75, 80 or 90 define the exact cup shape?

No. The size designation identifies the wire series, but the final choice should also match the wire contour, inner width, depth and cup pattern.

How many underwires are included in one pack?

The underwires in this category are supplied in packs of 50 pieces, which equals 25 matching pairs.

Can bra underwires be used in swimwear and bikinis?

Yes. They can be used in structured swimwear and bikini tops when the garment has an appropriate underwire channel and the wire matches the cup pattern.

How should the wire ends be handled during sewing?

The wire should be enclosed in a suitable underwire channel, with the ends protected by the garment construction to help prevent abrasion and improve wearing comfort.