PFA 4% in 1/3 SW Posted on December 5, 2024April 9, 2025 by Jennifer Ye 4% paraformaldehyde in 1/3 ASW Paraformaldehyde stock (EMS RT 15714): 32% To make mL fixativeat: % PFAadd: mL 32% paraformaldehydeadd: mL 1X ASW