A Flatlock seam is identified by a band of interlocked thread on both the inside and outside of the wetsuits seam. This stitch is created by putting two pieces of neoprene against each other and having the stitch penetrate all the way through the neoprene on both sides of the seam. Because the stitch penetrates the neoprene, it allows for a small amount of water and wind to pass through the seams. A Flatlock stitch is helpful in preventing rashes because it is flat, the Flatlock stitch is more suitable for warmer water wetsuits.
Glued and Blind Stitched Seams also known as GBS:
This stitch is when two pieces of neoprene are first glued together with waterproof glue then stitched together on the outside of the wetsuit. This stitched does not penetrate through to the other side of the neoprene, it only passes half way through the neoprene. The result of a glued and blind stitched seam is is a durable waterproof seam that keeps warmer because it is a sealed seam. Some manufacturers use double and triple gluing techniques as well as doubling the blind stitch, this reinforces the seams and makes them extremely durable. Often, if a stitch is broken, the thread will not continue to unravel. Wetsuits with a glued and Blindstitch seam typically cost more than those with a Flatlock stitch.
Taped/ Spot Taped Seams:
Spot tape is used to help prevent leaks or tears at the intersections and stress points of your wetsuit. Spot taping is also used to strengthen the seams within your wetsuit. Spot taping is typically used in conjunction with glued and blind-stitched seams create seams that are high performance and almost indestructible.
Fluid / Liquid Seams
The Fluid / Liquid seam is commonly found in cold water high end wetsuits. Manufacturers use a durable fluid rubber, (known by many different names), along the seams of the wetsuit to create a waterproof barrier along the seams of a wetsuit. This liquid rubber can be applied to the outside of the wetsuit along the seams, the inside of the wetsuit along the seams or both internally and externally. The advantage over a GBS (Glued and Blind Stitched) seam or a combined GBS and taped seams is that the Fluid Seam is the most watertight seam and it often is also GBS. There is a small trade off with a Fluid seam, they have been know to be a more rigid seam therefore decreasing some flexibility in the wetsuit, however, in wetsuits that use this type of seam, the neoprene is typically very flexible. Not all Fluid Seams are the same, some have no stitching and some are stitched and Fluid Taped or Fluid Sealed. Often manufacturers brand their Fluid seams with different names, try not to get confused now that you know more about the principles of this technology.