Thermolite
Invista engineered hollow-core polyester fiber designed for lightweight insulation. Used as fill or in fabric blends for cold-weather activewear.
Score Breakdown
How long the fabric lasts with regular use
Softness, feel against skin, wearability
Air flow and ventilation
Heat retention and insulation
Ability to pull sweat away from skin
Environmental impact of production and disposal
How easy it is to wash, dry, and maintain
Best For
Excellent warmth (85) and durability (75) for cold weather
Excellent durability (75) and comfort (65) for office wear
Good comfort (65) and care ease (78) for casual wear
Good moisture wicking (70) and durability (75) for weather protection
Good durability (75) and breathability (50) for outdoor activities
Detailed Use Case Scores
Pros
- ✓ Excellent warmth without bulk
- ✓ Lightweight hollow-core fibers trap air efficiently
- ✓ Retains insulating ability when wet
- ✓ Quick-drying compared to down
Cons
- ✗ Petroleum-based and not biodegradable
- ✗ Less warm per gram than down
- ✗ Can compress and lose loft over time
- ✗ Limited breathability
Care Guide
Special Notes
• Machine washable — retains insulation when wet
• Tumble dry low
Additional Care Tips
- • Machine wash cold (30°C/85°F) on gentle cycle with mild detergent
- • Tumble dry on low heat — some heat helps restore loft in hollow-core fibers
- • No ironing needed — Thermolite insulation does not wrinkle
- • Avoid fabric softener and bleach which degrade the hollow-core fiber structure
- • Store uncompressed when possible to maintain insulation loft over time
- • Follow garment manufacturer guidelines — Thermolite is usually part of a layered construction
Cost
$$$$$
Mid-range
Shrinkage
Won't shrink with normal washing
Eco Rating
High environmental impact