Is the pillow eiderdown or polyester?

Duck down is better and there is no chemical residue.

Polyester fiber is a kind of chemical fiber, which is artificially synthesized, and one of them is polyester. Fabric made of polyester fiber is one of the commonly used fabrics in clothing, which is wear-resistant and durable. Polyester fiber is also a commonly used filler, which is used for pillows, toys, quilts, etc., and is white and curly. Most of the dolls you mentioned are filled with this polyester fiber.

But the disadvantage is that sometimes some chemical residues or some harmful substances are volatilized.

Natural duck down will be better.