Is the Hardener added for additional strength?

Article courtesy of Smooth-On, Inc.

No, the term Hardener is really a misnomer.  The Hardener is ammonium chloride and works as a pH adjuster to insure proper cross-linking of the VF-812 and the dry resin.  Adding more Hardener to the mix design will not make FMG any stronger or make it set faster.


This FAQ article is offered as a guideline and offers possible solutions to problems encountered during mold making and casting. No warranty is implied and it is up to the end user to determine suitability for any specific application. Always refer to the provided Technical Bulletins (TB) & Safety Data Sheets (SDS) before using any material. A small scale test is suggested to determine suitability of any recommendation before trying on a larger scale for any application.