Abstract: A catalyst composition and a foundry method for the rapid production of cured, high tensile strength foundry sand shapes from a foundry mixture containing a furan-based binder and polyvinyl alcohol are disclosed. The polyvinyl alcohol is incorporated into a special thermally-activated strong acid salt catalyst prior to admixture of the catalyst composition with the sand and a furan-based binder. The sand-binder-catalyst composition is then shaped and the sand shapes are heated, resulting in exceptionally high tensile strengths in short times. In foundry methods involving in situ heating of the sand shape within the pattern, clean release (without sticking) from the pattern after cure is achieved.