Summary
Discover how Eationwear co-engineered a bonded sports bra for a top Australian activewear brand, delivering clean aesthetics, strong support and reliable bulk production quality.
Developing a Bonded Sports Bra for a Top- Activewear Brand (Lorna –Type Project)
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- Issue Time
- 2025/11/29 23:04:41
Client Background
A leading Australian activewear brand, Lorna , approached us while preparing a new premium training collection. The key hero item of the line was a bonded sports bra:
Clean, minimal aesthetic (no visible stitching on the neckline and armholes)
Soft, second-skin comfort with enough support for medium–high impact
Long-lasting bonding performance after repeated washing and high-sweat workouts
As a top global brand, they already worked with multiple factories, but struggled to find a partner who could combine bonding technology, accurate fit, and mass-production consistency at the same time.
The Challenge
The brief looked simple on paper, but technically it was demanding:
No visible stitches on key edges (neckline, armholes, back cutout), requiring bonding + laser-cut finishes.
The bra needed to be comfortable like a yoga bra, yet supportive enough for running and HIIT.
The main fabric was a high-stretch, high-recovery interlock, which makes bonding more challenging (risk of peeling or cracking when stretched).
The inner structure used power mesh + removable cups, which had to be bonded or neatly integrated without bulk.
The collection had to be launched in time for a global campaign, so sampling rounds and testing windows were limited.
The brand’s main concerns were:
Will the bonding hold up after sweat, salt, and repeated washing?
Will the bra keep its shape and support after high-intensity training?
Can you keep the aesthetic super clean while controlling quality at 5,000+ pcs per color?
Our Solution
Co-Engineering the Bra: Fabric & Bonding System
Our technical team started with a joint engineering session:
Evaluated the original design and suggested slight changes to make it more bonding-friendly (e.g. edge radius, overlap width, reinforcement points).
Tested different bonding films/tapes (PU-based with various thicknesses) on the client’s chosen fabric and inner power mesh.
Ran small lab tests on:
Bonding peel strength
Stretch & recovery under repeated cycles
Heat stability and yellowing risk
We finally selected a medium-thickness PU bonding film that balanced:
Strong adhesion
Enough flexibility to follow the body
A clean edge without “strike-through” marks on the fabric surface
Pattern Engineering for Bonded Construction
Traditional sewn bras and bonded bras cannot share the exact same pattern. We therefore:
Re-engineered the neckline, armhole, and back curves with bonding overlap in mind (usually 8–12 mm bonding area depending on fabric).
Added internal bonded support zones in the underbust and side panels instead of visible seams.
Optimized the strap connection points to avoid stress concentration that could cause bonding failure.
After the first prototype, we adjusted:
The cup height and side coverage for better support
The strap length and angle to reduce pressure on shoulders and keep the neckline stable during jumping and running
Sample Iterations, Lab Tests & Wearer Trials
We went through three structured sample rounds:
Proto Sample (Fit & Construction)
Confirmed basic fit, coverage, and bonding concept.
Sent to the brand’s in-house team for on-body review.
Size Set & Test Sample
Graded XS–XL and produced a complete size set.
Conducted internal wash tests (30+ cycles) and stretch tests to simulate gym usage.
Adjusted a few bonding parameters where small edge lifting appeared after aggressive stretching.
Pre-Production Sample (PPS)
100% aligned with bulk materials and final workmanship.
Used by the client’s wear-test team in real workouts (running, HIIT, strength training).
Feedback focused on comfort and support balance — we refined the underbust tension slightly for sizes L–XL.
Process Control in Mass Production
Bonding quality is extremely sensitive to temperature, time and pressure. To secure consistency, we:
Locked detailed SOPs for each bonded part (neckline, armholes, straps, back) including:
-Machine temperature range
-Pressing time
-Pressure setting
-Cooling time before moving the garment
Trained a dedicated bonding team and assigned inline QC inspectors just for bonded areas.
Implemented inline peel tests every fixed number of pieces to ensure bonding strength.
Used Four-needle six-thread (4N6T) stitching only in hidden structural areas where bonding was not suitable, keeping both comfort and support while preserving the clean look.
Results & Impact
The final bonded sports bra successfully met the client’s technical and branding expectations:
Aesthetic:
Ultra-clean, minimal look with no visible topstitching on main edges.
Edges lay flat against the skin with no rolling or cutting in.
Performance:
Passed 30+ wash cycles with no delamination in lab tests.
Maintained support and fit after repeated high-impact workouts in wearer trials.
Quality & Consistency:
First-pass quality rate in bulk production reached 98%+.
Client’s internal QC and third-party inspections both cleared with no major issues.
Business Outcome:
The bra became one of the key hero products in their campaign.
The client extended the style into new seasonal colors and requested us to develop a matching bonded legging for the next collection.
Example Client Comment
“We were looking for a partner who truly understands bonded construction, not just basic sewing. Eationwear helped us co-engineer a bonded sports bra that looks incredibly clean, feels soft, and still delivers the support our customers expect from a top activewear brand. The transparency in testing and production control gave us real confidence in scaling this style globally.”
— Head of Product, Leading Australian Activewear Brand
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