Feel and look
Wool felt is denser and drier to the touch, with a natural matt surface. Polyester felt is softer and slightly fluffier, and comes in more colours.
Price
Wool felt typically costs several times more. Polyester and recycled PET felt make large runs and promotional items affordable.
Heat
Wool chars rather than melts, which is why it is used for ironing mats and trivets. Polyester softens at high temperature; check hot-cup use for coasters.
Care
Both prefer cold cleaning. Wool shrinks with heat and agitation; polyester can deform in hot washes.
What you can say
For polyester felt, the recycled PET share if it is documented. For wool, the fibre composition and origin if known. Avoid general words like “natural” or “biodegradable” without explanation.
See wool felt and recycled PET felt.

