The Science of Insulation: Down vs Synthetic Jacket

When shopping for a new sleeping bag or puffy jacket, one of the most important decisions you will have to make is whether to get one with down insulation or synthetic insulation.

The type of insulation directly affects the warmth, weight, water resistance, compressibility and price of sleeping bags and jackets. Both down and synthetic have pros and cons when it comes to performance, so choosing the right type of insulation for your use can turn a cold, uncomfortable outing into an enjoyable time outside.

How To Choose Down vs Synthetic Jacket

To simplify your decision-making process, we, at The American Jackets, will help you take a closer look at down and synthetic insulation.

Down Insulation Jacket

One common misconception is that down is made from the feathers of a bird. Rather, in ducks and geese it is found beneath the outer feathers and looks like soft light strands. While some products do combine the two materials feathers are not down.

This type of insulating material is lightweight due to its air entrapping quality making it ideal for traveling purposes since it can be packed easily into small spaces. Furthermore, down also is breathable as well as durable thus making it perfect for use. Especially, when you need to keep warm in cold dry conditions or simply want to reduce your load during backpacking.

Down insulation has typically been sourced from geese. In recent years, major manufacturers have shifted to duck down because goose down has become expensive. Additionally, duck down and goose down have similar testing and performance standards; hence, the choice between the two is a personal one. However, you will notice that in most high-end products, goose down is still widely used since its fill-power rating is higher compared to that of duck down.

Fill power refers to how well lofting it traps heat thus measuring its ability. Therefore, this is determined by finding out how many cubic inches of space each ounce of down fills up in a testing device. For instance, 600-fill-power means that one ounce of this particular type can fill 600 cubic inches. Premium goose down may have as high as 900 fill power or even more than this. On the other hand, duck downs can only be rated up to 750 or 800 for fill power.

Sleeping bags and jackets filled with higher-fill-power-down require less volume of this material to achieve a certain temperature grade. Therefore, lighter products are manufactured using lesser amounts of these materials. Moreover, it is important to realize that a sleeping bag rated +20°F with 700-fill-power down will weigh less than a +20°F bag made from 600-fill-power down (assuming the fabrics and other features are comparable in weight).

The main reason why people avoid down insulation is that it becomes lumpy and loses its loft in the presence of moisture, which affects its insulation properties. In addition, many proprietary technologies have been developed to treat microscopic levels of water-resistant applications on down. This implies that down can resist mild wetness while still maintaining its loftiness. Nevertheless, even treated down will become wet if it is submerged in water or subjected to heavy rain, so you should strive to protect your down-filled items from getting damp.

Pros

• Warmer for less weight than synthetics
• Highly compressible
• Very durable; a properly cared for down sleeping bag or jacket can last for decades

Cons

• Loses insulating power when damp and takes longer to dry
• Cleaning down requires special attention
• Not hypoallergenic (rarely an issue)
• More costly than synthetics

Synthetic Insulation Jacket

Normally made of polyester, synthetic fill dries quickly and insulates even when wet (which is not the case with down). Additionally, it is generally cheaper than down insulation, as well as being long-lasting and suitable for persons with allergies.

There are many different trademark names used for synthetic insulation thus making it difficult to purchase one. However, another useful distinction is whether a synthetic insulator is a short-staple or continuous filament.

The short-staple insulation has short strands of fine-denier filaments that are tightly packed to achieve minimal heat loss. Thus, they feel soft and pliable like down-filled products do, making sleeping bags and jackets comfortable and easy to carry. Nevertheless, continuous filament is more lasting than this type of insulation, which may shift hence creating cold spots.

On the other hand, continuous filament insulation mostly employs a thicker continuous filament that is lofty and strong. In comparison to short-staple insulation, they feel stiffer and are not as compressible; however, they do not move so there are fewer chances for cold spots.

Pros

• Very water-resistant and still maintain insulation even when wet
• Hypoallergenic
• Less expensive than a down

Cons

• Heavier and bulkier than down insulation
• Offers less warmth for its weight than down
• Less durable than down; insulating power gets reduced each time the bag is stuffed into a stuff sack