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Vents & Layering

Oct 7, 2022


- Down
- Synthetics
- Thermal liners

- Ultrasonic Welder explorations 

Thermal Equation

The human physiology is extremely complex, and providing warmth is not the only factor that needs to be taken into account in order to keep a person warm. As shown above, the type of activity will generate more or less heat from the user's body. Depending on the intensity of the activity, and the outside environment, that heat will either need to be kept in the user's clothing, exit the garment, or be redistributed to other areas. Humidity also comes into account, especially when the insulation method chosen is down. 

Down insulation

Down insulation

         Down insulation is still the most effective insulation available. However, it looses it stops retaining warmth when wet. This means that if the user is too warm in a down insulated piece of apparel, they could start sweating profusely, en end up getting cold from their own body humidity diminishing the down heat retention power. It is important to note that down insulation is different from feathers, it is the small duvet present under feathers and is characterized by its high ability to trap air. This potential to retain air pockets is measured by assessing the volume 30 grams of down occupies. The bigger the volumes, the more air is trapped, and the more potent the insulation provided will be. Construction of the baffle comes into account when trying to reduce heat loss to.a maximum. A boxed baffle or trapezoidal construction remove any direct heat loss through stitching. Alternatively, a welded baffle will also reduce the level of heat loss. It will still however, have no insulation at the points of welding, where a boxed baffle will provide a thick, consistent insulation level over the whole garment surface.
          Down insulation is at the heart of many discussions regarding ethics and animal suffering. When considering this issue, one also needs to look at the sustainability level of down compared to synthetic insulation. 


         In order to regulate the body temperature, many outdoor brands use zippers. Armpit zipper openings are extremely used in the outdoor industry. They allow for a clear opening of highly protective garments (from the rain, the wind, or the cold), at one of the most heat productive area of the body. While not always the most functional or easy to operate (when worn with a backpack, or for users with reduced shoulder movements for eg.), they are the most efficient, simple, and modular solution that has been implemented in the technical apparel industry. 
          Fixed vents, under a back yoke, or under armpits, are also a great way to get rid of heat but cannot be closed like the armpit zips allow. Two way zippers, as illustrated above, allow access to a harness or pockets, or stored accessories without risking to loose all the heat trapped in the garment's microsystem. 

          So as to reduce heat loss, and handle moisture better, the technical apparel industry built the layering system. An ensemble of layers, allowing for each of them to handle a complex characteristic of thermoregulation. Base layers are utilizing wicking fabrics to pull moisture away from the skin and direct it towards the outer layers, so it can exit the user's microsystem. Mid layers allow for heat retention, while letting body vapour and moisture exit their structure. Finally , shells are the barrier protecting the body from the outside elements. When waterproof, even with breathable properties, they may be unable to let body heat escape from the system of dress microsystem as fast as body heat is produced. This is when vents come into play, to make sure the user's insulation doesn't get saturated by moisture.

Sweating manikins

         Sweating manikins allow testing of the evolution of body vapour in a garment. They can be static or slightly mobile (walking motion), and different zones of the manikin can be parameterized with different sweating levels so as to mimic a human body. These manikins are a critical asset to test technical apparel and get a first idea of how a particular garment will handle heat and moisture produced by a human form, before putting it to the test on a human person and risking injuries or heat strokes. This can also indicate chafing areas, or where the humidity is most likely to gather and create a discomfort or a risk zone.

In Class Exercise 

Welding machine experimentation

           I decided to experiment with synthetic insulation and test shapes of welding patterns. I realized that the three layers of fabric: facing, insulation sheet, lining, tend to slide against each other under the welding foot. In addition there is no guiding foot on this machine, making the fabric quite complex to handle. One needs a lot of focus and practice to come up with straight seams. The settings are a very important aspect, needing to match the type of fabric used, so that the seem doesn't come apart at the slightest pull, nor makes a whole in the fabric.
          I believe this technique is extremely interesting but may be more relevant for the medical industry, or for elements that don't require the level of strength and durability of a stitched seem. When aiming for a more "sealed" insulation, I think boxed baffles shapes are more efficient and relevant than ultrasonic welding.

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