Surfaces made of the nonreactive materials Au and graphite exhibit low surface potential variations after a low‐temperature ultrahigh vacuum bake. The variations (due to the finite size crystallites of these materials) may be reduced to a minimum by using Au surfaces of grain size less than 10 nm and graphite surfaces with highly alignedc‐axis orientation. Procedures where this may be accomplished are described. Application to the Los Alamos antiproton gravity experiment is presented.