Technical Outerwear Development & Manufacturing
Launch Your
Outerwear Line.
Our Services
Garment Development
Premium apparel — from blanks to fully engineered outerwear.
NANJING, CHINA
Specialist Manufacturing Access
Technical outerwear production through rigorously vetted specialist factories with internationally recognised certifications and proven experience in waterproof-breathable garment construction.
TAIWAN, JAPAN + CHINA
Performance Textile Network
Access to specialist performance-textile mills across Asia, including suppliers in Taiwan, Japan and China producing waterproof laminates, lightweight technical nylons, ripstop constructions, downproof textiles, stretch-woven shells and specialist linings.
ASIA-WIDE SUPPLY NETWORK
Technical Components and Trims
Access to YKK® zippers, seam tapes, cord systems, adjusters, insulation, specialist linings and lower-MOQ technical components.
Garment Manufacturing, On the Ground
Headquartered in Shanghai
Real people, on real factory floors, running your garment production in China.
Jing'an District · Shanghai
Founded by Tom Stevens, Seam Department was built through seven years living and working in China alongside garment factory owners, pattern makers, mills and production teams.
We don't work through a middleman or a trading company. Our team is physically in the factories — reviewing fit samples, checking fabric against approved lab dips, and inspecting bulk production before it ships.
That includes technical outerwear. Waterproof-breathable construction, seam sealing, and membrane laminates run through rigorously vetted specialist factories with internationally recognised manufacturing certifications — not a generic garment factory that also happens to say yes to outerwear.
We build the complete production framework — design documentation and prototyping, supplier matching, sample development, in-person production oversight, quality control and delivery — so international brands get a real point of contact in China, not a quote from a stranger on Alibaba.
Our in-house prototyping lab lets us validate construction and resolve pattern and fit details before we approach a factory. Presenting mills and cut-and-sew partners with a developed prototype and production-ready tech pack removes the guesswork from quoting — more accurate pricing, fewer cost buffers, and a clearer path from sample to bulk.
7
Years in China
500+
Factory Visits
155+
Brands Supported
3,000+
Partners in Asia
Tom Stevens — Founder & Director, Seam Department
Technical Outerwear Infrastructure
Everything Required to Develop Performance Outerwear.
Waterproof Shell Materials
2L, 2.5L and 3L laminates sourced according to weight, durability, stretch, breathability, waterproofing and intended garment use.
Seam-Taped Construction
Specialist seam sealing for waterproof jackets and pants, developed around compatible fabrics, tape systems, machinery and controlled application settings.
Specialist Manufacturing Access
Technical outerwear production through rigorously vetted specialist factories with internationally recognised manufacturing certifications and proven experience in waterproof-breathable garment construction.
Performance Textile Network
Access to specialist performance-textile mills across Asia, including suppliers in Taiwan, Japan and China producing nylon ripstop, waterproof laminates, downproof textiles, stretch-woven shells and high-performance outerwear materials.
Technical Components
YKK® zippers, waterproof closures, cord systems, adjusters, seam tapes, reinforcement materials and specialist trims sourced as part of the complete garment system.
Insulated Construction
Puffer-shell materials, natural and synthetic insulation, lining systems, chamber construction and fill-level development for insulated jackets and vests.
Material Sourcing
Performance fabrics, linings, insulation, trims and components sourced according to technical requirements, hand feel, colour availability, minimum order quantities, lead times and intended garment use.
Tech Pack Development
Production-ready technical documentation covering garment measurements, construction details, material specifications, bills of materials, trims, artwork placement and factory manufacturing instructions.
Pattern Development
Technical garment patterns developed according to fit, layering requirements, articulation, mobility, seam construction and the intended performance of the finished product.
How Technical Outerwear Projects Run
From initial product direction to finished delivery, every technical outerwear project moves through three documented and controlled phases.
01Phase 01 — Define
Understand
We establish the garment's purpose, intended environment, target customer, performance requirements and commercial position before design work begins. This gives every later decision a clear reference point and prevents the product from becoming a collection of disconnected features.
- Define intended use, climate and performance expectations
- Establish target customer, retail position and production budget
- Confirm initial quantities, launch dates and commercial constraints
- Prioritise the garment's essential functions and features
Define
Digital Concept Development & Product Engineering
We establish the garment's purpose, intended environment, target customer, performance requirements and commercial position before design work begins. This gives every later decision a clear reference point and prevents the product from becoming a collection of disconnected features.
- Define intended use, climate and performance expectations
- Establish target customer, retail position and production budget
- Confirm initial quantities, launch dates and commercial constraints
- Prioritise the garment's essential functions and features
Phase 01 Benefit
The first sample begins from a resolved product direction rather than being used to discover what the product should have been.
What We Manage
One Technical Garment System. End to End.
Materials and Components
- Performance fabric sourcing
- Waterproof laminates
- Nylon ripstop and Taslan
- Downproof puffer materials
- Natural and synthetic insulation
- Linings and reinforcement fabrics
- YKK® zippers and closures
- Seam tapes and technical trims
Garment Development
- Product feasibility
- Technical drawings
- Production-grade tech packs
- Bills of materials
- Measurement specifications
- Pattern development
- Construction documentation
- Trim and colour development
Sampling and Validation
- Prototype development
- Fit and articulation review
- Construction revisions
- Seam-tape trials
- Material compatibility checks
- Insulation and loft development
- Pre-production samples
- Approval documentation
Manufacturing
- Technical shell jackets
- Waterproof shell pants
- Seam-taped rainwear
- Puffers and insulated garments
- Premium T-shirts and basics
- Hoodies and sweat sets
- Cut-and-sew collections
- Production quality control
Launch Your Technical Outerwear Line.
Access performance-textile mills, specialist components and certified technical manufacturing through one on-ground development team.
@imtomstevens
Follow the Work in Real Time
Factory visits, garment production, and the realities of building apparel in China — documented by Seam Department founder Tom Stevens.