I've been meaning to make a cosy in this style for quite some time - but as with most things, too many ideas and not enough time!
Although knitted in double knitting yarn, carrying the yarn at the back of the work and pulling it tight creates the fluted effect which will certainly keep your teapot hot.
The pale neutral pastel shades make it ideal for most kitchens as it will 'blend into the background' - unlike many of my other tea cosies!
This and other tea cosies are available in my Etsy shop now.