How can I tell silk from polyester?

Silk is warm to the touch, breathable, and has a soft uneven luster; it also wrinkles and water-spots more easily. Polyester feels cooler and more slippery, shines more uniformly, resists wrinkles, and does not absorb moisture. A burn test is definitive but destructive: silk smells of burnt hair, polyester melts.

Why was polyester compared to silk?

Polyester was developed in part to mimic silk's sheen and drape at a fraction of the cost, just as rayon and nylon had been. It captures the look but not silk's breathability or temperature regulation.

Which is better in summer?

Silk, generally, because it breathes and regulates temperature, feeling cool in heat. Polyester does not absorb moisture and can feel clammy, though some performance polyesters are engineered to wick sweat.

Side by side

Silk vs Polyester

Silk and polyester can look alike in a shiny blouse, but one is the natural filament a silkworm spins and the other is a synthetic spun from PET plastic, and polyester was in part invented to imitate it. Silk is luxurious, breathable, and temperature-regulating but delicate and costly. Polyester is cheap, strong, wrinkle-resistant, and quick-drying but less breathable, and it can feel and smell different against the skin.

Silk

No. 128

the filament fiber, often woven satin or plain · first documented Antiquity

Polyester

No. 122

woven or knitted from PET filament or staple · first documented 1941

The differences

Aspect	Silk	Polyester
Origin	The natural filament from the silkworm's cocoon.	A synthetic polymer spun from petroleum-derived PET.
Comfort	Breathable and temperature-regulating; cool in heat, warm in cold.	Low breathability; can feel clammy and hold odor.
Sheen and hand	Deep, soft, natural luster and a fluid hand.	Often shinier in a harder, more uniform way.
Durability and care	Delicate; sensitive to sun, sweat, and water spotting; often dry-clean.	Strong, wrinkle- and shrink-resistant, machine washable.
Cost	Expensive.	Cheap, and the most-produced fiber in the world.

Which to choose

Choose silk for natural luxury, breathability, and a deep luster, accepting the price and the care. Choose polyester for durability, easy care, and low cost, accepting that it breathes less and feels different. Polyester imitates silk's look but not its comfort.

Common questions

How can I tell silk from polyester?: Silk is warm to the touch, breathable, and has a soft uneven luster; it also wrinkles and water-spots more easily. Polyester feels cooler and more slippery, shines more uniformly, resists wrinkles, and does not absorb moisture. A burn test is definitive but destructive: silk smells of burnt hair, polyester melts.
Why was polyester compared to silk?: Polyester was developed in part to mimic silk's sheen and drape at a fraction of the cost, just as rayon and nylon had been. It captures the look but not silk's breathability or temperature regulation.
Which is better in summer?: Silk, generally, because it breathes and regulates temperature, feeling cool in heat. Polyester does not absorb moisture and can feel clammy, though some performance polyesters are engineered to wick sweat.

Full entry: Silk Full entry: Polyester

Sources & References

1.Silk, Wikipedia
2.Sericulture, Wikipedia
3.Polyester, Wikipedia
4.Polyethylene terephthalate, Wikipedia