Crushed, Compressed, Hyper-Compressed, etc.
What is the difference?
Written By Bob Stinton, Vice President Engineering, DUI and Susan Long, Vice President/Chief Operations Officer, DUI
Competition is fierce, even in the diving industry. When someone sticks their neck out, tries something new and different and it works, it doesn't take long for others to come along and hook a wagon to their star. Such is the truth about crushed neoprene. This is a patented process by DUI though others would like you to think that by using words such as compressed, micro-cell, hyper-compressed, etc., that it is all the same thing. It is not.
The first thing you need to know is CRUSHED IS DIFFERENT. It was developed in response to a U.S. Navy requirement. The Navy called for a shell-type drysuit that was durable, swimmable and had little or no intrinsic insulation: a shell drysuit. A good example of how a shell drysuit works is a raincoat. A raincoat works by providing a waterproof barrier which can be used during a warm summer shower over a T-shirt and shorts or during a freezing rainstorm worn over layers of clothes. The raincoat keeps you dry and what you wear underneath it keeps you warm and comfortable. A shell drysuit allows the diver to adjust the level of insulation to the demands of the environment and dive. The shell drysuit also does not experience the loss of insulation and buoyancy changes with depth as does a foam suit.
Another reason both the U.S. Navy and DUI were looking for a new material was that the most common materials used for making drysuits, then and now, is closed-cell foam neoprene (A.K.A. wet suit rubber.) Durability was and always has been a common problem with this material. Just the action of compressing and expanding of the cell structure weakens the material, not to mention kneeling, sitting or banging in to things. Weakening of the material leads to cell rupture which leads to water seepage. And no more dry suit.
One of the areas investigated by DUI was the possibility of permanently compressing closed cell neoprene foam to make a stretchable waterproof barrier. Why permanently compressed foam? During the development of free-flooding hot water suits, it was found that suits used for deep saturation diving become permanently compressed or, as we called it, crushed. The 5mm foam's cell structure was completely gone. The only problem was this ruptured the cell walls. The challenge was to find a method that would permanently collapse the cell structure without rupturing the cell walls.
This thought process led to a series of experiments involving several major factors: pressure, temperature and time. We also learned during this process that not all foam neoprene worked the same. The key to the process was to get the cells in the foam to not only compress, but to completely off-gas during the process and not re-expand. The effort resulted in a process that transformed closed-cell structure into a stretchable water-tight barrier. An evaluation of the sample material by the Navy Clothing and Textile Research Facility suggested that it was an entirely new class of material. Based on this analysis the U.S. Patent Office issued two patents: 4,882,785 Underwater Diver's Dry Suit having a Permanently Compressed Cellular Layer and; 4,788,643 Method of Treating an Underwater Diver's Suit, resulted in the CF200 series drysuit.
Most would agree that the DUI CF200 series drysuits are the standard by which all other drysuits are measured. That has spawned a lot of imitators. Manufacturers started using the word "compressed" thinking that a diver might think that is the same as DUI's crushed. Compressed neoprene is simply thinner wet suit rubber. Granted, some are better then others. The "hyper-compressed" or "micro-cell" are better performing materials because they use a smaller cell structure. That is why DUI manufactures the CNSE which is made from 1.5mm Hyper-Compressed neoprene. The thinner the better as it will give the diver flexibility and comfort with reasonable durability. But it doesn't hold a candle to crushed (CF.)
DUI actually makes the suit then crushes it. This process off-gases the material and makes a water-tight barrier. The problems with foam neoprene are non-existent with crushed foam. There is no cell structure to rupture. And because it is a shell drysuit, there will be no buoyancy change with depth. The durability is increased because the cell walls are layered against one another creating a virtually impenetrable barrier. Unlike fabric shell drysuits, the CF is stretchable providing a closer fit. Nothing is like a CF200.
Some manufacturers even go so far as to say they purchase neoprene that is 4mm thick and it was compressed down to 2 or they took their suit that is 5mm thick and compressed it down to 3mm. If this is true, then the thinner suit would have the same rubber content as the thicker suit, meaning they would weigh the same. So just pick up a thicker suit in one hand and a thinner suit in the other hand. If they don't weigh the same then it's not true. Period.
To show you that we're not biased, Abyss also offers crushed foam, however they use an entirely different process. However it is the material combined with the workmanship, the reputation, the fit and the features that make the CF200 a true benchmark in performance and quality. After all, they wouldn't be copying it if it wasn't the best.