Methods for producing thin keratin films, sheets, and bulk materials, and products formed using these methods. One method includes providing hair, reducing the hair such that the disulfide linkages are broken and free cysteine thiol groups formed, separating out a more soluble keratin fraction in solution, forming a thin layer from the more soluble fraction, and air drying the keratin fraction in the presence of oxygen, thereby forming new disulfide bonds imparting strength to the resulting thin keratin film. One method includes reducing hair by heating the hair under nitrogen in an ammonium hydroxide and ammonium thioglycolate solution followed by centrifuging and collecting the supernatant containing the more soluble keratin fraction. The more soluble keratin in this method is precipitated using HCl, removed, and resuspended in ammonium hydroxide. The keratin solution thus formed is poured onto a flat surface and allowed to air dry into a thin keratin film. The film may be used as a wound dressing, a tissue-engineering scaffold, a diffusion membrane, a coating for implantable devices, and as a cell encapsulant. In another method, the keratin solution thus formed is concentrated, poured into a mold, and allowed to air dry into a three dimensional keratin product. The resulting bulk product can be used as a cross-linked implantable biomaterial for soft and hard tissue replacement. In another method, a keratin solution is emulsified and freeze dried, forming a porous, open cell keratin material.