PrimaLoft Explained

A cold, wet day outside is fine as long as you're warm, and that's the idea behind PrimaLoft. It started as a US Army project in the early 1980s, when the brief was for insulation that kept working after getting soaked, and now it fills jackets, gilets, gloves, sleeping bags, and boots. Below, you'll find how it compares with down, what Gold, Silver, and Black mean, how much you actually need, and how to wash it.

What Is PrimaLoft?

PrimaLoft is a brand of synthetic insulation made from very fine polyester fibres. Albany International developed it in the early 1980s for the US Army, who wanted something that did down's job (light, squashy, warm) without going flat the moment it got wet.

PrimaLoft insulation works the way down does, by trapping air. The fibres are bonded together at tiny contact points, which leaves little pockets of still air in between, and they're treated to shrug off water instead of soaking it up. That treatment is why a PrimaLoft jacket keeps its warmth through a downpour.

You'll find it in jackets, gilets, gloves, sleeping bags and boots, and the exact type changes from garment to garment.

PrimaLoft vs Down

Down wins on warmth for its weight, and it packs smaller when it's dry. The catch is a wet day: soaked down clumps up, loses its loft and takes ages to dry out. PrimaLoft keeps insulating when it's damp and dries a lot quicker, so it makes more sense if you'll be sweating hard under the jacket or standing about in drizzle. PrimaLoft says its Gold and Silver insulations hold on to more than 94% of their warmth when wet and dry about four times faster than untreated down.

Down still has the edge when the cold is dry and every gram and litre of pack space counts. If the forecast looks damp, or you'd rather avoid animal materials, go with PrimaLoft.

How Does PrimaLoft Match Up to Down Fill Power?

Fill power is a down measurement, so fully synthetic PrimaLoft doesn't have one. Brands compare it with down loosely instead, and standard PrimaLoft Gold is usually put somewhere around 500 to 600 fill. Down Blend is the exception. It's PrimaLoft's hybrid, mixing the ultra-fine fibres with real down, and PrimaLoft does give fill power equivalents for it:

PrimaLoft Gold Down Blend matches the warmth of roughly 750-fill power down.
PrimaLoft Silver Down Blend matches the warmth of roughly 650-fill power down.

Which Products Come With PrimaLoft?

PrimaLoft isn’t limited to jackets. The same insulation goes into gilets and gloves too, and each one uses it a little differently. Open a product below to see what to look for.

A PrimaLoft jacket is the usual starting point: a light insulated layer that works under a shell or on its own on dry, cold days. When you're comparing PrimaLoft jackets, look at the named type and the weight of the fill, not just the brand, since a Black-insulated jacket and a Gold one aren't built for the same level of warmth.

If you want a jacket with PrimaLoft for damp, changeable weather, that's where synthetic does better than down. Rab, Montane and Patagonia all use PrimaLoft in parts of their insulated ranges.

A PrimaLoft gilet keeps your core warm without the bulk of sleeves, which helps when a full jacket would have you overheating. If you'll wear it for riding or running, choose an Active version: the stretch and breathability suit stop-start effort, and your arms stay free.

Gloves are the first thing to get damp, which makes water-resistant insulation more useful here than in a jacket or gilet. PrimaLoft gloves use the same insulation in a thinner layer. Gold shows up in technical pairs, with Silver or Black in lighter everyday ones.

More insulation isn't automatically better in a glove, because it costs dexterity. Pick the amount that matches how cold your hands run and what you need them to do.

What Do Gold, Silver and Black Mean?

PrimaLoft's main insulation ranges are Gold, Silver and Black.

Gold sits at the top for warmth relative to weight, and it's the one used where performance counts: technical jackets, gloves and footwear. Silver is the middle tier, a balance of warmth and low weight that suits general use. Black is the entry tier, aimed at casual and lightly active wear.

Some versions of each are made with recycled material, and the garment label usually names the exact type, such as Gold Eco or Silver Eco. It's worth reading that name rather than stopping at the brand, because two garments that both say PrimaLoft can sit at different levels of warmth.

How Much PrimaLoft Do You Need?

Warmth depends on the type of PrimaLoft and how much of it is in the garment. That amount is given in grams per square metre (g/m²), so 100 g means 100 grams of insulation across each square metre of fabric, not a jacket that weighs 100 grams. More grams mean more warmth and more bulk.

Caring for PrimaLoft

It's low-maintenance, but a few habits keep the loft in good shape:

Check the care label, close the zips and turn it inside out
Wash gently at 30°C with a mild liquid technical detergent, and rinse well
No fabric softener, bleach or spin cycle
Drip dry and shake it out, or tumble dry low with two or three tennis balls to restore the loft
No ironing or steaming
Store it loosely, not squashed in a stuff sack, which flattens the loft
One wash at the end of the season is usually enough, sooner after a sweaty one
Refresh water repellency with a spray-on proofer, since wash-in ones can coat the insulation

Choose the type to match the activity: Gold or an active version when warmth for weight or stretch matters, Silver for general use, and Black for casual wear. Then pick the format, jacket, gilet or gloves, for where you want the warmth.

Browse insulated jackets, gilets and gloves at Cotswold Outdoor to find the PrimaLoft type that suits you.

FAQs

Ultra-fine polyester fibres. Some versions use recycled material, and the Bio version uses biodegradable fibres.

Down is warmer for its weight when it's dry. PrimaLoft keeps insulating when it's wet, which is where down struggles.

No. The fibres repel water and keep insulating when damp, but the outer fabric of the jacket decides how much rain gets in.

Yes. It's a synthetic insulation with no animal materials.

Gold is the top tier for warmth relative to weight. Silver is the middle tier, a balance of warmth and weight for general use.

Generally yes, in cold water on a machine cycle, with a gentle dry. Check the care label on the specific item.

Some versions are. Look for the type named on the label, such as Eco, rather than assuming every PrimaLoft garment uses recycled material.

Both are synthetic insulations that keep working in damp conditions, but they come from different companies: PrimaLoft makes PrimaLoft, and 3M makes Thinsulate. Each comes in several types and weights, so compare the specific type and fill rather than the brand name alone.

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