This hat is a simple application of decorative increasing and decreasing in double-knitting. Six banners or flags in 3 different Celtic knot motifs run diagonally around this hat and up to a spiral at the crown. Sizing this hat is very easy — the banners stay the same, but you add more pairs between them if you need a larger size. The more pairs between the banners, the more dramatic the crown spiral becomes! Also, because of the increases and decreases done in every round, the stitches in the spaces between the banners seem to run nearly horizontal. This is an illusion, of course, but a great generator of double-takes when you show off your hat — at least to other knitters. The crenellated brim is a function of the increases and decreases, and also becomes more dramatic the more pairs are inserted between the banners.
The word “bratach” means “flag” in Gaelic. I highly recommend you search out Mouth Music’s first album for the song “Bratach Bana” or “white flags”. True Scots may find the version a little untraditional, but I’ll never forget my reaction to it when I heard it as a child.