A basic experiment compared two different alterations (modified postpalatal strap and the "Ristau post-dam") of maxillary casts before flasking and processing with a control (unaltered maxillary casts). This experiment evaluated whether the alterations of the maxillary cast and its subsequent flasking procedures can alter the palatal separation in the postpalatal seal region between the master cast and the simulated denture. Ten trials each were performed for the modified postpalatal strap, the Ristau post-dam, and the unaltered maxillary casts (control). Subsequent to the flasking and processing, measurements were made to evaluate the palatal separation in the postpalatal seal region. After two statistical analyses, improvements (decreased palatal separation) were noted with the use of the modified postpalatal strap (with the mechanical undercuts) technique. In addition, measurements were made to compare results before and after 72 hours of hydration.