Wetsuit Seam Guide for Manufacturers: Flatlock vs. GBS vs. Taped

In the competitive world of wetsuit manufacturing, seam technology is a key differentiator. Brands constantly push for warmer, more flexible, and more durable seams—moving from basic flatlock to advanced Glued and Blind Stitched (GBS), and further to fully taped or liquid-sealed constructions.

But as a manufacturer, you know a hidden truth: advanced seams place immense stress on the base material. A GBS seam requires a foam core that won't tear when glued. A taped seam requires a fabric laminate that won't delaminate under heat and tension. The integrity of the seam is only as good as the integrity of the neoprene sheet it joins.

This is a technical guide to the three primary wetsuit seam technologies, viewed through the lens of material compatibility. As the material engineers at https://neoprenecustom.com, we design our neoprene sheets specifically to be the robust, reliable foundation that advanced seam technologies require.

Level 1: The Flatlock Stitch

• What it is: The two pieces of neoprene are overlapped slightly and stitched through completely from one side to the other.

• Best For: Summer wetsuits, spring suits, rash guards (water temperature above 18°C / 65°F).

• Material Compatibility:

  • Pros: Highly compatible with almost any grade of neoprene (SBR, SCR, CR). It’s a robust, mechanical bond that doesn't rely heavily on adhesives.

  • Cons: It creates thousands of needle holes that let water through. It is not waterproof and offers poor insulation.

• Manufacturer's Note: While forgiving, a high-quality, high-stretch jersey laminate is still recommended to prevent the stitch threads from pulling at the fabric and causing runs over time.

Level 2: Glued and Blind Stitched (GBS)

• What it is: The edges of the neoprene panels are first glued together end-to-end (butt joint) to create a watertight seal. Then, a specialized curved needle stitches into the neoprene surface but not all the way through to the other side.

• Best For: Mid-range to high-end cold water suits (water temperature below 15°C / 59°F).

• Material Compatibility - The Critical Factors:

  • Foam Density & Tear Strength: The butt-joint glue relies entirely on the internal strength of the foam core. If the foam is too low-density or weak (like cheap SBR), it can tear right next to the glue line under tension. High-quality SCR or 100% CR foam is essential.

  • Thickness: GBS is difficult on very thin neoprene (under 2mm) because there isn't enough depth for the blind stitch needle to grab without punching through.

• Manufacturer's Note: Our neoprene sheets are engineered with a high internal tear strength specifically to support robust GBS construction without failure.

Level 3: Taped and Liquid Sealed Seams (Advanced)

• What it is: This is an enhancement to a GBS seam.

  • Taped: A flexible, waterproof tape is applied with heat and pressure over the GBS seam on the inside of the suit for reinforcement and comfort.

  • Liquid Sealed: A bead of liquid rubber silicone or urethane is applied over the exterior (and sometimes interior) seam, creating a 100% waterproof, highly durable, and windproof seal.

• Material Compatibility - The Critical Factors:

  • Lamination Bond Strength: This is the #1 failure point. Taping applies heat and tension to the interior fabric lining. If the lamination bond between the fabric and the foam is weak, the tape will pull the fabric right off the foam (delamination).

  • Heat Stability: The heat required to apply tape or cure liquid seals can shrink or distort low-quality neoprene foam. A heat-stable, high-quality CR core is required to maintain dimensional accuracy.

• Manufacturer's Note: At neoprenecustom.com, we use advanced, high-strength lamination adhesives and heat-stable foam cores designed specifically to withstand the rigors of heat taping and liquid sealing processes without delaminating or distorting.

As you move up the ladder of seam technology, the demands on your raw material increase exponentially. A cheap sheet of neoprene might be fine for a flatlock summer suit, but it will cause catastrophic failures if you try to use it for a liquid-sealed winter suit.

Don't risk your brand's reputation on a material that can't handle your manufacturing process. Partner with a material supplier who understands the demands of advanced construction.

We can provide you with:

• High-tear-strength CR foams for secure GBS joints.

• Ultra-high-bond laminations for secure taping.

• Heat-stable cores for precise liquid sealing.

To get samples of our "advanced construction ready" neoprene sheets to test on your own production line, contact our technical specialist, Kevin, at kevin@neoprenecustom.com.