The datasheet indicates the most appropriate blocking solution for your experiment. The blocking solution should be made fresh before each use. Common blocking agents for specific applications are listed below.
Application  Blocking agent*  Western blot5% BSA of 5% non-fat milk Immunofluorescence/ Immunocytochemistry (IF/ICC)
10% serum from the species in which the secondary antibody was raised. Alternatively, 1% BSA or 1% gelatin
*Blocking agents should be fully dissolved before adding the antibody. Undissolved blocking agents may result in artifacts being generated during your experiments.