Why are down jackets so expensive? How to choose a warm and money-saving down jacket?
Drop its feathers and you get 5 pounds of duck meat to fill your belly, and 100g of down to warm your body.
Why does down keep you warm? How to pick a warm and affordable down jacket? You will know after reading this article
An important indicator to evaluate the thermal performance of a material is the "thermal conductivity". The smaller the thermal conductivity, the slower the rate of heat transfer, the warmer the material.
And air, is the best warm material, thermal conductivity is only 1/3 of cotton, than any piece of clothing on your body to keep warm.
Of course, it must be still air so that it does not carry heat away through thermal convection. Like the insulation commonly used on the walls of northern buildings, is the use of still air to insulate the heat transfer.
Unfortunately, you don't have the means or the guts to wear only still air. To keep warm in civilization, you have to find a clothing material that can store a lot of still air.
Silk, wool and cotton are all superior natural warming materials, but down is the best one among them, no one, thanks to its special structure.
Look closely at the duck's feathers: these are the positive and fibrous feathers, also called "feather pieces", accounting for about 90% of the total feathers, but not warm; this is the down feathers, also called "down", which is the key to keeping the down jacket warm.
There is a tiny nucleus in the center of the velvet, which is connected to dozens of velvet branches, each of which has a large number of velvet twigs growing on it.
Through the microscope, you can see many triangular or fork-shaped nodes and countless tiny pores on these velvet twigs.
Inside these fibers, there are also numerous gaps and cavities. These structures allow the fleece to store large amounts of still air, reducing heat transfer.
On the other hand, the surfaces of the fleece branches and fleece twigs also carry a small charge that repels and separates from each other, resulting in the formation of radial fleece dots.
Countless fuzz, fuzzy branches and fuzzy twigs are overlapped together to form a dense web of fibers that keep the air still and reduce heat convection.
So the nature of down, which happens to be a static air storage, it can use a limited volume and mass to fix down as much air as possible, so that you can feel the hug of feathers in the cold winter.
According to universal standards, a qualified down jacket needs to be labeled with the name of the down filling, down content, and filler, and they are some of the most important indicators when selecting a down jacket.
Down filling refers to the amount of down. Generally speaking, the higher the down content of the down jacket, the better the warmth effect.
But this is not absolute. If the density of the down fibers is too high, it will reduce the amount of air stored and the heat will be more easily lost through fiber conduction.
And the higher the down filling, the bulkier the down jacket will be. So if you are not going on an expedition to the coldest places, it is enough to choose a down jacket with a down filling of about 100 to 200g.
The down content of a down jacket is more important than the amount of down filling. Down content refers to the proportion of down in the down, the higher the proportion, the better the warmth.
A decent down jacket needs to have at least 50% down content.
If the down content is very low, then the filler may have a lot of stray hairs, impurities, or "crushed down" from the crushed wool processing, they are not only poor warmth performance, elasticity is also very poor.
In addition, some high-end down jackets are also marked with fluffiness, which refers to the volume of down that can be filled per unit mass. The higher the fluffiness, the more air can be stored in the down and the better the warmth.
The higher the fluffiness, the more air can be stored in the down jacket, and the better the warmth; and high fluffiness also means that the down jacket can be warm and light without too much filling. A medium quality down jacket, the fluffiness is usually around 400 to 500, enough to keep you warm on a daily basis.
But the down jacket you buy is often not marked with the size of the fluffiness, so you can feel the elasticity of the down by pressing it, and the faster it bounces back, the better the fluffiness tends to be.
As for the fillers, there are mainly these categories. They all originate from two kinds of birds: ducks and geese.
Ducks have a short growth cycle and high slaughter volume, so 90% of the down is duck down, and the price is relatively cheap.
Geese have a long growth cycle and are farmed in smaller quantities, so in the early days they were mainly plucked alive to obtain goose down, and the poor geese would even suffer painful prolapse during plucking.
After 2009, with the concern of animal protection organizations and rising labor costs, the market for live-pulled down products gradually decreased, the production of goose down decreased, and the price was more than twice as expensive as duck down.
In terms of warmth, goose down has a smaller nucleus, larger pile, and higher fluffiness, so the warmth is relatively better.
However, according to this study, the same volume of duck down and goose down, insulation rate difference of about 5%, the difference is not significant, but the price of the two types of down jacket can be two to three times the difference.
In addition, the color of the down will also affect the price. Gray down will show through the light-colored fabric color, affecting the perception, generally used in the dark down jacket filler, the price is relatively cheap;.
The white ducks and white geese are less in number, and with marketing and promotion, the output of white down will be much more expensive.
If you do not discriminate against ducks and ducks with darker fur, then it is quite good to choose a dark down jacket filled with grey duck down.