The extraction of gamma-prime sample residues from Ni-based superalloys varies greatly in efficiency with the type of heat-treatment that had previously been applied to the alloy; this effect has prompted the present formulation of a standardized procedure for measuring the residues' filter-clogging factor (FCF). The FCF differences between heat treatments can be correlated with the quantity and size distribution of extracted particles; this procedure could accordingly furnish a means of checking the accuracy of heat treaments.