A ski jacket placket is a water-management system disguised as a strip of fabric. Snow sits on the chest, wet lift seats press against the hem, and the wearer generates heat on the way down and cools on the lift. The zipper line is the weakest continuous element in that system, and it is the place where a jacket that looked waterproof in a showroom starts to feel damp after two hours on the mountain.
This note covers a typical resort jacket: a 2-layer or 2.5-layer shell, a 10,000-20,000 mm water column target, a fixed hood, pit zips and a chest pocket. It assumes the garment is sold as waterproof, not water-resistant, and that the buyer expects the placket to survive a full season of use.
1. Requirement: what waterproof means at the placket
Water reaches the chest through three routes: through the zipper teeth, along the tape by wicking, and through the stitch holes that attach the flap. A specification should address all three:
- Pressure: no visible leakage at the placket under a hydrostatic head equal to the garment rating, tested before and after washing.
- Wicking: no moisture transfer along the tape from a wet outer surface to the inner lining in a 30-minute wicking test.
- Wind: the flap must stay closed in wind without a snap at every 10 cm; skiers open and close the chest constantly.
- Glove use: the puller must be operable with a insulated glove, and must not require pinching a small tab.
- Flex: the placket must not crack or stiffen at -15 degrees Celsius.
The last two points are often missed in lab specifications and are the first things a ski shop hears about from customers.
2. Selection: coated coil, membrane zipper or flap-first design
There are three practical constructions. The first is a standard coil with a polyurethane coating on the tape and a storm flap over it; it is the cheapest and, when the flap is deep enough, adequate for resort use. The second is a specifically waterproof zipper with a sealed tape and a coated chain; it costs more, looks technical, and removes the need for a deep flap. The third is a flap-first design in which the zipper is a normal coil and the flap, plus an internal gutter, does the waterproofing.
For a jacket with a 20,000 mm rating, the second or third route is usually necessary. A bare coil with a shallow flap will pass a new-sample spray test and fail after ten washes. If the design wants a visible waterproof zipper without a flap, choose a matte tape and a chain that matches the shell tone, and accept that the slider will be larger than a fashion zipper.
Slider selection matters in cold weather. Metal sliders feel cold and can freeze to the tape when wet; moulded bodies with a rubberised puller are more comfortable with gloves. A lock body is still needed, but the lock should release cleanly with a gloved pull rather than requiring a precise squeeze.
3. Key processes: flap depth, sealing and drainage
The storm flap should overlap the chain by at least 25 mm on each side for a resort jacket, and the flap should be backed by a gutter that directs water sideways rather than into the chain. The flap's top and bottom ends need particular attention: a flap that stops exactly at the top stop leaves a gap where snow collects, and a flap that ends above the hem lets water run back into the opening.
Seam sealing around the placket is not optional. Tape the seam that joins the flap to the front panel, and seal the zipper tape ends with a small patch rather than folding the tape under, which creates a capillary path. Avoid stitching through the waterproof tape of the zipper itself; every needle hole is a leak path unless it is covered. Where a chest pocket meets the placket, offset the pocket seam by at least 10 mm so the two taped seams do not overlap and create a hard, leak-prone lump.
Pit zips should be treated as part of the same system. They are usually the first place a jacket leaks, not because the zipper is poor but because the flap is short and the seam is not taped. Use the same waterproof zipper family and the same sealing method as the front placket.
4. Testing and acceptance
Acceptance should combine lab and wear simulation:
- Hydrostatic head: test the placket area at the garment rating, before washing and after five washes at 40 degrees Celsius.
- Spray test: 30 minutes of simulated wet snow at the placket, with the wearer leaning forward, then inspect the inner lining.
- Wicking: place a wet pad against the outer tape and check for moisture at the inner edge after 30 minutes.
- Cold flex: condition at -15 degrees Celsius, then open and close 200 times; check for tape cracking and slider stiffness.
- Freeze test: wet the placket, freeze it, then operate the slider; record the force needed and any damage.
- Glove test: a panel of users operates the slider with ski gloves and rates it; reject if more than a small proportion needs two hands.
Photograph the inner surface after each test. A faint dark line along the tape is the earliest sign of wicking and is much easier to act on than a wet chest liner in the field.
5. Common risks and how to close them
The classic failure is a placket that is waterproof when new and leaks after washing, because the DWR on the flap has degraded and the tape wicks. Specify a re-proofing instruction and test after washes, not only on new samples. A second risk is a flap that is too short at the top, leaving the slider exposed to snow. A third is a waterproof zipper installed with a standard needle and a dense stitch, which perforates the coated tape and defeats the coating.
Two production risks deserve a mention. First, seam tape applied over a curved placket end wrinkles and lifts; use a smaller tape or a patch at that point. Second, a last-minute change from a 2-layer to a 2.5-layer shell changes the surface energy and can make the same tape peel. Freeze the shell and the tape together before bulk production, and keep a retained sample of the approved combination for later disputes.