Drysuit Zipper Selection and Care December 26 2016
Drysuit zippers are pretty impressive for the fact that they actually work. Let’s look at the issues of zipper selection and care.
A plastic watertight zipper on Mythic Gear's Taruba drysuit
Metal Versus Plastic
Drysuit zippers are described as being made of either plastic or metal. That actually describes just the teeth of the zipper “chain,” and the teeth by themselves don’t create the watertight seal. When you zip a waterproof zipper closed, the teeth lock together in order to pull plastic or rubber sealing surfaces on the two sides against each other. These sealing surfaces are quite narrow, and on casual inspection they don’t appear to be a significant part of the zipper. They are, however, the real basis of its water-tight functionality, so the teeth must have very close tolerances to hold the sealing surfaces together tightly and in alignment.
Metal watertight zipper on a Mythic Gear Kiwa drysuit
Metal zippers are usually made of bronze, which has excellent anti-corrosion properties. They tend to be extremely rugged and durable. They are, however, stiffer and bulkier than plastic zippers, forming a fairly rigid ridge across the drysuit. Their operation is also stiffer, requiring more effort to open and close. And because their teeth are smaller and closer together than on plastic zippers, smaller bits of sand or other grit can cause them to jam.
Plastic zippers are more flexible and lighter in weight. This makes them more comfortable and allows the drysuit to be packed or rolled tighter with less chance of damaging the zipper. They are easier to open and close than metal zippers, although they still require more effort than a conventional non-waterproof zipper. They are less prone to jamming than metal zippers, but not quite as rugged, although their reliability is excellent.
Wash and Wax the Zipper
The Number One rule in caring for drysuit zippers is to keep them clean. Dirt and grit in even small amounts can interfere with the smooth movement of the zipper slider over the teeth and prevent the teeth from engaging. A tiny bit of dirt between the two sealing surfaces can allow water to seep through and into the suit. If used in salt water, salt deposits can cause the same problems.
It’s a good idea to wash the whole drysuit after every use, but if you don’t do that, at least clean the zipper. Open the zipper and submerge the suit in clean water or work under running water. Using a soft-bristle brush, brush side to side across each side of the zipper chain separately on the inside and the outside to clear any grit from between the teeth and off of the sealing surfaces. Rinse thoroughly.
Periodically run a block of beeswax or canning wax (i.e., paraffin) along the teeth of metal zippers and especially near the end stop. (Zip Care by McNett also works well as a lubricant, and the bottle comes with a small brush attached.) Do not wax the teeth of plastic zippers, but do apply wax or petroleum jelly to the special surfaces at the end stop. Use only a very light coating of wax or jelly in either case, as it can attract and hold grit.
In the Field
Store drysuits with metal zippers open and plastic zippers closed. When packing the drysuit for travel, avoid over-bending the zipper by rolling the suit loosely around a bundle of other clothing or a towel. Over-bending is a more serious concern for metal zippers. It can create a permanent kink, which will make the zipper inoperable. The only solution is replacement, which is expensive.
Plastic zippers are more forgiving of being bent into a small radius, but you still want to avoid bending them so tightly that the teeth might separate in the middle of the chain.
To operate the zipper, pull the slider slowly, using your other hand to hold the suit fabric straight and tight and keep the two halves of the zipper in alignment. If the zipper jams, don’t pull harder. Instead, back it up, realign the fabric on the two sides, and try again. If it jams again in the same place, examine the zipper carefully for an obstruction (even a single grain of sand could be the problem) or a bent or misaligned tooth.
Avoid getting the zipper dirty. Don’t drop your drysuit on the ground. If you must lay it on the ground, do so with the zipper facing up. If the zipper does get dirty, clean it before using it. You do not want to jam grit into the teeth or sealing surfaces by closing the zipper when it’s dirty.