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When you’re out in the cold and wet its vital to keep warm. The warmest outdoor jackets use an insulation material sandwiched between a outer shell. Just like with sleeping bags, there are two main choices for insulation material. These are either down or synthetic. Both of these insulation materials loft up, trapping air voids which is warmed by your body heat. Outdoor gear manufacturers are constantly trying to come up with new ways to advance insulation technology and one such product is PrimaLoft’s ThermoBall. This is a down-like synthetic fill used exclusively by The North Face.

Insulation materials for outdoor jackets and sleeping bags

Primaloft ThermoBall, Synthetic and Down Insulation



Before talking about ThermoBall, below is a short a summary about down and synthetic materials and their pros and cons.

Down Insulation

Down consists of soft feathers taken from birds, usually geese or ducks. Down insulation provides an excellent warmth to weight ratio, packs down to a small size and is long lasting. The drawbacks to down are that it is expensive, it does not insulate when wet, it must be washed with special cleaning products and there are serious welfare concerns over the way the birds are farmed.

Synthetic Insulation

Synthetic insulation is made from polymer strands that are intertwined into a matting. Synthetic insulation does not provide as much insulation and is heavier than down, however it has the major advantage that it will still keep you warm when it is wet. It can also be washed with normal detergents.

ThermoBall Synthetic Insulation

Last year The North Face and PrimaLoft launched a new type of synthetic insulation material called ThermoBall. Instead of being made into a matting, Thermoball fibres are clustered together into little balls. The cluster structure is designed to be similar in nature to that of Down.

Unlike traditional continuous-filament synthetic insulations, the small, round PrimaLoft synthetic-fiber clusters closely mimic down clusters, trapping heat within small air pockets to retain warmth. The North Face

Independent tests, on behalf of The North Face, at Kansas University found ThermoBall Insulation to be equivalent to Goose Down with a 600 Fill Power Rating. The Fill Power of Goose Down ranges from 600 to 900, depending upon the source of the down.

So ThermoBall provides insulation that is as good as Down, yet since ThermoBall is synthetic it lofts and provides insulation when wet too. There is of course some way to go before synthetic insulation is as good as the best quality down in terms of fill power.

A not so scientific test by Sean McCoy at Gear Junkie tested The North Face ThermoBall Jacket by immersing it is a cold mountain stream before going out for a walk in the snow. He found that ThermoBall did provide insulation when wet and that his jacket had dried out after he had been wearing it for two hours.

The logo for The North Face / PrimaLoft ThermoBall

The North Face ThermoBall Jackets

We are currently selling three The North Face jackets that use ThermoBall insulation. They are the ThermoBall Jacket, the Women’s ThermoBall Hoodie and the Women’s Plasma ThermoBall Jacket.

The North Face ThermoBall Insulated Jacket has a nylon shell made from 100% recycled plastic. The similar The North Face Women’s ThermoBall Hoodie has a polyester ripstop shell. Both are multi-activity jackets suitable for use as a mid- or outer-layer jacket down to temperatures below freezing.

The breathable, waterproof HyVent outer shell on The North Face Women’s Plasma ThermoBall waterproof jacket means that it will protect you from the rain as well as providing thermal insulation. The Women’s Plasma ThermoBall is part of the Outdoor Explore range and is a great jacket for walking, hiking and general outdoor use.

Jackets from The Nort Face conating Primaloft ThermoBall Insulation

The North Face ThermoBall Jacket and Women’s Plasma ThermoBall Jacket

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