Winter bark is birch bark that is gathered earlier than Summer bark. The winter bark is harvested in my region from of May until beginning of June. On the other hand, summer bark can be peeled from mid June to August. The winter bark has a dark brown skin called cambium on which it is possible to scrape designs. It is more difficult to peel than summer bark that is why I use a piece of teflon to take off the bark carefully. Summer bark peels really easily but has a clear golden color on which it is not possible to carve.
Detail of winter bark designs on the side pannel of a malecite style canoe. The brown layer is scrapped off leaving the clear natural color underneath.