Masterfully designed canoes of many sizes and forms were made on the Northwest Coast by carving from solid logs, usually of red cedar but in some areas of Sitka spruce or cottonwood. Typically these boats were widened beyond the original diameter of the log by the spreading of the steam-softened sides. Spreading does more than widen the canoe; it introduces major changes of form throughout the hull which the canoemaker must anticipate in carving the log. The straight and level gunwales bend smoothly out and down, while the ends rise, forming a graceful sheer and transforming a rigidly narrow, hollow trough into an elegant watercraft.

In order to spread without splitting, the walls of the hull are made remarkably thin (only three-fourths of an inch in the 62-foot Haida canoe in the American Museum of Natural History, for example). When the hull is completely carved, water is poured into it to a depth of six inches or so, and heated to boiling with red-hot rocks. The resulting steam is confined by covering the open hull with mats. The hot rocks are replaced as needed to keep the water at a boil. The softened sides, heated through by the steam inside and fires outside, begin to move outward, aided by the weight of water and rocks pressing down in the centre. Spreading sticks are tapped into place between the gunwales, and are moved towards the ends and increased in length in the centre as the sides flare outward. When the planned beam and form are reached, the canoe is allowed to cool, the water is removed, and the thwarts, bow and stern blocks, and gunwale caps are fitted and fastened in place. Large travelling and war canoes were often painted with designs associated with the names of the canoes or the crests of the owners.

In the picture, a medium sized Haida canoe is just reaching its finished width; one last load of hot rocks helps to thoroughly soften the hull. As the covering mat is lifted, steam rolls up, partly obscuring the big plank houses with their massive frontal poles on the bank above the beach. Haida canoe makers were widely respected and their products in demand throughout the northern Northwest Coast. Perhaps this canoe is destined to be taken across Hecate Strait to be traded at the Nass River for eulachon grease, mountain sheep horns, or other mainland products not available on the Queen Charlotte Islands.