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Denali Gear Guide

Types of Synthetic Insulation

Almost everyone has somewhere in their closet a piece of synthetic insulated gear, but what is the difference between the Thinsulate in your gloves, the Primaloft in your jacket, and the Polarguard in the sleeping bag you want to buy? The array of Synthetic insulation choices out there can be a bit dizzying at times, so we are here to provide a breakdown of the most common types and their primary uses.

Generally, it is worth keeping in mind that warmth is really a function of trapped air space. So, while some materials insulate more efficiently than others, it is really loft that makes the big difference in how warm a garment or sleeping bag is.  Many articles provide a good gauge of the thickness of their insulation by putting a gram-weight number right on the tag, like “60 gm/m Coreloft” in the Arc'Teryx Atom LT.  That number refers to the weight in grams of one square meter of the insulation.  So, thicker, warmer insulation will weigh more per square meter and hence have a higher number.  As a guide, 60 gm is on the thinner, lighter end of the insulation scale.  100gm is standard for mid-weight insulated jackets, and 150-200gm thicknesses can be found in really warm jackets.

In addition to trapping air, insulation works by reflecting the body’s radiated heat, preventing it from escaping into the environment.  Reflective barriers (like silvery hanging liners inside some jackets) work way better than synthetic insulations for this type of heat loss, but every once in a while you will see this function brought up on a manufacturer’s hang tag.


Down vs. Synthetic


Thinsulate, made by 3M, was one of the first name brand synthetic insulations out there, and was introduced back in 1979 with the slogan “warmth without bulk.”  It uses small diameter, mixed polymer fibers to provide insulation, so that it can pack more fibers in the same space to more efficiently trap air and reflect more radiating heat back.  Thinsulate is relatively inexpensive, and you see it most often in jackets and gloves.

Thinsulate examples:



Primaloft has occupied the opposite end of the construction spectrum from Polarguard, with soft short-strand fibers made from microfiber polyester.  Primaloft is highly compressible, very soft, and feels a lot more down-like than any other synthetic insulation.  It also has remarkable water-resistance properties.  The principle drawbacks to Primaloft are durability and price. Because of its short fibers, Primaloft is more prone to bunching and sees limited use in sleeping bags. While it is still cheaper than down, it is at the top of the price range for synthetics.  There are a few varieties of Primaloft, but the most commonly seen are Primaloft Sport, the value option, and the higher-end Primaloft One, which features finer fibers and more water resistance.  The newest material from Primaloft is called Infinity, and it is Primaloft’s entry into the continuous filament field.  Look for it to compete against Polarguard Delta in sleeping bags.

Thermolite is a whole family of synthetic fills from the same company that makes Coolmax Polyester.  Thermolite is hollow-core insulation focused on managing moisture, drying quickly, and keeping you warm when wet.  In its various forms, you see it in sleeping bags and all kinds of clothing.  The different grades are:

  • Active- lighter weight and quick wicking for higher output activities
  • Extra- high loft insulation that mimics the softness of down
  • Micro- lower bulk for the highest compressibility;
  • Plus- very hydrophobic fibers retain the most warmth when wet
  • Extreme- the highest warmth to weight ratio.

Climashield makes insulation that is continuous filament, like Polarguard, but with a focus on softer, more compressible products that can work in gloves, outerwear, and shoes in addition to sleeping bags.  They also treat their fibers with silicone to enhance water resistance. It shows up in products from The North Face and Patagonia among others, in three different incarnations:

  • CLIMASHIELD APEX claims to be the lightest weight and most thermally efficient continuous filament insulation on the market, with 75 percent more loft and 30 percent more thermal efficiency.  It is used in
  • CLIMASHIELD CL is engineered for maximum loft per unit weight and is seen only in sleeping bags. There is an earth-friendly version, called CLIMASHIELD GREEN, which offers equal performance and contains a minimum of 40 percent recycled polyester.
  •  CLIMASHIELD HL claims improved thermal efficiency, resilient loft and durability.  CLIMASHIELD HL GREEN offers all the advantages of Climashield HL, but with 100% recycled polyester filaments (Find out more about Green Clothing Options).

Proprietary Insulation:

It is worth it to mention that in addition to these brand-name materials, many outdoor brands complicate things further by using  their own proprietary insulation in lower price point items.  Here are a few of the common names in case you come across them on a hangtag and want more info:
  • Marmaloft by Marmot is similar to Thinsulate and found in several of their skiing and casual jackets
  • Coreloft is used by ArcTeryx in a few of their lightweight jackets.  It is similar to Primaloft Sport, with longer fibers introduced to try to improve durability.
  • Heatseeker is The North Face’s cool name for their synthetic insulation, which is a longer fiber insulation similar to Thinsulate.
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