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Neoprene Cements
Neoprene Cement Neoprene cements are very tough and flexible solvent-based contact cements made by mixing chloroprene resin with solvents and other chemicals. It most commonly comes in two flavors, black and yellow. The black is an opaque black, and the yellow may be yellow, tan, translucent amber, or even almost clear. So when a divesuit manufacturer calls for neoprene cement, it's important (unless you are gluing foam neoprene in which case you always use the black) to be clear about just what it is they are recommending - black or yellow. Black neoprene cement is normally used mainly for gluing neoprene to neoprene on neoprene and crushed neoprene wet and dry suits, and yellow for everything else. However, there isn't really that much difference between the two - the black is pretty much the same thing only with carbon added for coloring. For some reason, this seems to also make it more flexible, and age better. though, so many techs will use it anytime neoprene cement is called for and the black color will not be a problem. Halcyon recommends the black for gluing their pockets to suits regardless of material and many techs like it for bonding boots. Black neoprene cement is available in most diveshops from a number of suppliers, like Trident, Global and McNett, usually in brush top cans. There doesn't seem to be much difference between them - they all work fine, as long as they are black and come in a can.

Zippers
Most drysuits use waterproof zippers made by Dynat, YKK or BDM. BDM invented the waterproof zipper, and the top of the line BDM zipper with the riveted (instead of crimped) teeth is the undisputed heavyweight champion of the waterproof zipper world as well as being the zipper used on the astronauts' space suits. Divers may argue over which brand is best, but they are all now owned by YKK and YKK says that there is no difference in quality between the labels. There are, though, three different duty levels, each with a different tooth pitch, usually given in teeth-per-inch. Light duty 10 pitch is used mostly on outdoors and watersports gear, and maybe semi-dry suits, but rarely on drysuits except occasionally for relief zippers. Medium duty 8 pitch is used on the vast majority of drysuits. Heavyweight 6 pitch is used mostly for shoulder zipper installations on top-of-the-line or commercial suits. Most of the YKK companies make the light and medium duty grades, but only BDM makes the heavy duty. Divesuit manufacturers, however, often play it a little loose with these terms, and it is common to see an 8 pitch being referred to as heavy duty.

The words "Heavy Duty" have an aura that many technically-minded DIYers find irresistible, and the riveted-tooth 6-pitch BDM zipper is an item of great beauty, but 99% of the time you will do just fine using a medium duty zipper. There are also some applications where a heavy-duty zipper just plain won't work, mainly any place the zipper has to bend a lot, like the over-the-shoulder front zipper on a DUI self-donning suit. The bigger the teeth are, the less flexible a zipper is. Since waterproof zippers are pretty much a generic item now, you don't have to replace a zipper with the same brand or style as was originally installed. Any of the medium duty YKK 8 pitch zippers, what YKK refers to as a Proceal Awtight 8TZN, in neoprene will work fine in almost any drysuit application, though a heavier duty zipper may be preferred in a few instances - mainly heavy duty suits that will see hard use and that are still in very good condition.

Practice
Many of the procedures in divesuit repair, while not difficult, require a certain amount of manual dexterity and are easy to screw up the first few times one tries. Especially when using contact cements - they are quick to grab and tenacious so that just the briefest improper contact can be enough to make you have to start all over. The good news is that just about all of these procedures can be easily practiced first, either on scraps of material, or by running through the procedure "dry" - without applying any adhesive. For example, rolling the wrist seal off the form and onto the sleeve ( or even harder, a leg over a boot) is pretty simple when one gets the knack. But screw up a little and you've got a big wrinkle, and the whole thing will have to be redone. So do it dry a bunch of times until you got the feel, and it will go much better wet. Ditto sliding two pieces of neoprene smoothly together so they make even contact without being distorted or bunched. Seal cutting can also be practiced - on the old seals before you remove them. Since you are going to be discarding them anyhow, it makes more sense to perfect your latex cutting technique on them, than on the new ones. You can even practice zipper installation by putting some two-sided carpet tape on the zipper tape, then seeing how straight you can get without cheating and repositioning it once it's stuck. This might be overkill for a simple cross-shoulder zipper where the entire run of the zipper can be held flat and aligned in one step, but is a particularly worthwhile exercise if you will be doing an over-the-shoulder or other similarly convoluted installation.

 

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