The Complete Handbook of Coats & Jackets

Chapter 1: Understanding Coats & Jackets

The Outerwear System

Forget, for a moment, about fashion or style. At its most fundamental level, a coat or jacket exists to create a stable microclimate around your torso. It manages the exchange of heat and moisture between your body and the external environment. Your body generates heat through metabolism and activity; it also generates moisture, primarily through sweat. A garment that traps too much heat causes overheating and saturation. A garment that loses too much heat causes dangerous cooling. The humble coat is, therefore, an environmental control device, often surprisingly sophisticated in its construction, and its performance is determined by a handful of measurable, physical properties. This chapter establishes what a coat actually is, how it performs its job, and why an understanding of this physics is the dividing line between a successful purchase and an expensive mistake. The failure to understand this system is why millions of people are cold or wet in jackets that cost hundreds of dollars, while others stay warm and dry in garments that cost a fraction of the price.

The single most important concept in outerwear is not "warmth" or "waterproofing." It is the management of the microclimate immediately next to your skin.

What is the Job of a Coat?

A coat performs three primary functions, in varying proportions depending on its design: insulation, weather protection, and moisture vapour transport. Insulation is the ability to slow the transfer of heat from your warm body to the cold