A commonly known “Open Cell” wetsuit (technically a “Split Cell Inside) is a wetsuit that is NOT lined at all. Once the slab of Chloroprene master foam has been mechanically “split” (hence the correct appellation “split cell”), it becomes pure rubber with tens of thousands of tiny craters, which used to be the closed cells with the nitrogen gas filling. They now act as suction cups, eliminating any space between the skin and the wetsuit. This is why a diver must lube such a suit before donning it, using water, or water and soap, or best of all; water mixed with some hypoallergenic and fragrance free hair conditioner.
Freedivers generally refer to the best freediving wetsuits as “skin-in” or “open-cell”, when these wetsuits have no fabric lining.
This is simply because wetsuits are divided into two categories: Wetsuits with fabric lining and wetsuits without fabric lining.
By lining, we mean a fabric material, such as Nylon or Lycra that covers the inside of the wetsuit, which is in direct contact with the diver's skin.
However, both appellations are not technically correct. But we will compromise and accept them, in order not to complicate matters.
"Skin-in” may also be what is referred to as “smooth-skin” inside. Meaning that the Neoprene sheet was used as is, without “splitting”, therefore defeating the purpose of a perfect fit, adhesion and waterproofing. Many wetsuit manufacturers will use this design and market the wetsuit as “open-cell” or “skin-in”, thus confusing the divers.
Skin-in, or smooth skin in, is actually the upper and lower crests of the master foam after it comes out of the mold. Think of an angel cake that was just baked. Imagine the crusty surface that is smooth since it was the one exposed to the heat of the oven. Once you slice that part, the inside of the cake is spongy. Voila!
We at Yazbeck Wetsuits, we use that “crust” as a waterproof seal. You will find it in most of the Yazbeck wetsuits used as a face seal, wrist cuffs and leg openings. This is also the part that enters in the fabrication of the legendary Freedive Hunter socks.
However, Yazbeck never uses this part as a lining. It would defeat the purpose. The only linings that are acceptable to Yazbeck Wetsuits are either the “Open / Split Cell, Titanium Silver / Charcoal (NanoPrene Shield), BioCeramics (BoTermic ) , Impermeaflex, or in the case of some thinner wetsuits and some gloves and socks models; Nylon, Plush or Lycra or Spandex