This patent describes a treatment of land fowl feathers that modifies the cystine linkage of the keratin in order to improve their untreated filling power of 1.8 - 2.1 centimeters to 5.9 - 6.5 centimeters. Feathers are initially treated in a mixture of sodium hexametaphosphate and alcohol sulfate to solubilize blood contamination. Feathers are laundered with a non-ionic type detergent. To increase feather curliness, treatment involves immersion in an aqueous alkaline solution, rinsing and further immersion in a dilute aqueous solution of epichlorohydrin pH 6.4. The pH is increased to 9. 2 with a dilute alkaline solution. After two hours pH of the epichlorohydrin solution drops to 7.4. The feathers have been completely processed. This treatment increases the bulk value of the final feather product, renders it resistant to papain-bisulphite digestion and increases the resistance to microbiological attack. This is an industrial process applied to feathers that may have relevance for conservation or preservation of these materials. -- CCI