| What it is | Polyester fibers mimicking down loft |
| Strengths | Warm when wet, dries fast, cheaper |
| Trade-offs | Heavier, bulkier, shorter lifespan |
| Examples | PrimaLoft, Polartec Alpha, Thinsulate |
Synthetic insulation uses fine polyester fibers, arranged as continuous filaments or short staple clusters, to mimic down’s air-trapping loft. Its key advantage is that it keeps much of its warmth when wet and dries fast, plus it’s cheaper and hypoallergenic. The trade-offs versus down are more weight and bulk for the same warmth and a shorter useful lifespan.
Down’s wet-weather rival
Examples include PrimaLoft and breathable active insulation; it fills a synthetic jacket. See down vs synthetic.
Frequently asked questions
What is synthetic insulation?
Synthetic insulation is man-made fill, typically polyester fibers, engineered to trap air the way down does. It comes as continuous-filament insulation (durable, resists shifting) or short-staple insulation (softer and more compressible, closer to down's feel). It's used in jackets, sleeping bags, and other gear as a down alternative.
Why choose synthetic over down?
Because synthetic keeps insulating when damp or wet and dries quickly, making it more reliable in wet climates and for high-output sweaty use, and it costs less and is hypoallergenic. The downsides are that it's heavier and bulkier for the same warmth and gradually loses loft over time faster than quality down.
What are common synthetic insulations?
Well-known examples include PrimaLoft (a high-performance, down-like synthetic), Polartec Alpha (a breathable 'active insulation'), and 3M Thinsulate (a thin, warm fill). Each balances warmth, weight, compressibility, breathability, and cost differently for various uses.
Sources
- Down vs synthetic — The Mountaineers
- Insulation basics — American Hiking Society