I knew wool triggered allergic dermitis for Thor but was sure if I knit him a hat from very fine micron fibers, his skin would be fooled. No such luck, though I used extremely fine merino (the black yarn) and baby alpaca (the blue yarn).
Now, however, two years later, we are living in a much colder climate than San Francisco, and Thor pulled out this hat and tried again. Same result.
So for this interim birthday present (while I design and knit his cardigan sweater), after turning the band of the hat up, I picked up stitches and knit an internal hat out of a two ply 100% organic cotton yarn.
The already warm wool-alpaca hat is now lined with cotton (making it even warmer). With the band turned up, no protein fiber touches Thor’s skin, and his ears are protected by a third layer.