Methods, apparatus, and compositions related to generating and using thrombin. Methods include preparing a solution comprising thrombin by precipitating fibrinogen from a liquid comprising whole blood or a blood fraction. Precipitated fibrinogen is removed from the liquid to form a post-precipitation liquid that is incubated with calcium and a plurality of beads to form a clot. A solution comprising thrombin is separated from the clot. Thrombin prepared thereby can be used as a tissue sealant and in methods of applying a tissue sealant to subject, including application of an autologous tissue sealant.