Sulphur-containing scleroproteins such as keratins are softened and modified by treatment with solutions of dialkyl esters of thiocarbonic acids.  Hair, wool, feathers, nails, albumens of sinews, collagen of bones, gristle, and connective tissue, may be treated. The softened materials may be shaped as desired and then set by an oxidation treatment or by treatment with aldehydes or alkylene dihalides.  The alkyl esters of thiocarbonic acid may contain hydrophilic groups such as carboxyl, sulphonic, or hydroxyl. Specified esters are: trithiocarbonic acid bis-(carboxy-methyl ester), dithiocarbonic acid -O-S-bis-(carboxy-methyl ester), dithiocarbonic acid -SS1-bis-(carboxy-methyl ester), trithiocarbonic acid bis-(a -carboxy-ethyl ester), and trithiocarbonic acid bis-(a -sulphonic acid n-butyl ester).  The alkyl esters may be used in an aqueous solution or in methyl, ethyl, or propyl alcohol.  The solution may contain borax, sodium metaborate, sodium carbonate, ammonia, tri-sodium phosphate, perfumes, wetting agents, emulsifiers, and additional reducing agents such as hydroxylamine.  For subsequent oxidation there may be used hydrogen peroxide, other per-compounds, addition products of urea with per-compounds, bromates, or atmospheric oxygen.  Instead of an oxidation, the materials may subsequently be treated with alkylating agents such as alkylene dibromides or with formaldehyde or glyoxal.ALSO:Sulphur-containing scleroproteins such as keratins are softened and modified by treating them with solutions of dialkyl esters of thio carbonic acids.  The keratin substance treated may be that of hair, wool, feathers, or nails.  Albumens of sinews and the collagen of bones, gristle, or connective tissue, may be treated. The process may be used for the permanent waving of hair, for straightening naturally curly hair, or for removing hair.  The treated material is more receptive to dyestuffs, moth-proofing agents, and other chemicals.  The softened materials may be shaped as desired and the imparted shape may be rendered permanent by oxidation or treatment with aldehydes or alkylene dihalides. After this further treatment, the materials are more resistant to the action of alkalies.  Preferably, the alkyl esters of thiocarbonic acid contain hydrophilic groups such as carboxyl, sulphonic, or hydroxyl groups.  Specified alkyl esters are:-trithiocarbonic acid bis-(carboxymethyl ester), dithiocarbonic acid-O-S-bis-(carboxymethyl ester), dithiocarbonic acid - SS1 - bis - (carboxymethyl ester), trithiocarbonic acid bis-(a -carboxyethyl ester), and trithiocarbonic acid bis-(g -sulphonic acid n-butyl ester).  The alkyl esters are preferably used in aqueous solution but they may be used in solution in methyl, ethyl, or propyl alcohol. Hair may be treated at 25-40 DEG  C., using solutions of 5-25 per cent concentration and a treatment time of 1/2 to 2 hours.  If the reagents contain acidic groups they may be used in the form of their alkali salts. The solutions preferably are alkaline and for this purpose salts such as tri-sodium phosphate, sodium carbonate, borax, sodium metaborate, or ammonia may be added.  Perfumes, wetting agents, emulsifying agents and additional reducing agents such as hydroxylamine may be added.  For the subsequent oxidation there may be used hydrogen peroxide, per-compounds, addition products of urea with per-compounds, bromates, or atmospheric oxygen.  Instead of an oxidation, the materials may subsequently be treated with alkylating agents such as alkylene dibromides or with formaldehyde or glyoxal.