Croissant lamination 81-layer technique

Professional croissant lamination for flaky layers. Butter block: 250g European butter (82% fat). Dough: flour, milk, yeast, sugar, salt. Process: 1. Encase butter block in dough square. 2. First fold: roll to 20x60cm, letter fold (3 layers). 3. Chill 30 minutes. 4. Second fold: roll and fold again (9 layers). 5. Third fold: final lamination (27 layers, with 3x3 structure = 81). 6. Final roll to 4mm thickness. 7. Cut triangles, proof, egg wash, bake at 375°F. Explain butter temperature control and avoiding smearing.