The French term for the lamination process used in croissant making is tourage.
During tourage, a slab of butter is enclosed in détrempe, the basic dough, and the package is rolled and folded several times. Each fold multiplies the layers of dough and butter while the dough is rested and chilled to keep the butter firm. This careful temperature control is essential: warm butter blends into the dough, while overly cold butter can crack and create uneven layers.
Tourage is sometimes confused with related terms. Feuilletage generally refers to the flaky laminated structure or pastry itself, while beurrage describes incorporating or applying butter. Croissage is not the standard French name for this croissant-making operation.
After tourage, the dough is rolled thin, cut into triangles, and shaped. Proofing then allows the yeast to expand before baking turns the butter-separated layers into a crisp, airy crumb.