It's \link{http://www.ikea.com/gb/en/catalog/products/30105618/#/80168769\this one} - the first 4 covers are all 100% cotton & washable, but the last 3 are mixed fibres (this one is 50% viscose/rayon, 30% linen, 20% polyester) & it says they aren't
I know viscose shrinks, but then so does cotton...