Heat applied during vulcanization turns any moisture held in the rubber compound into steam, and that steam forms bubbles and porosity in the finished part. A dehydrating agent — also referred to as a desiccant or anti-bubble agent — is added to bind the moisture before it can become steam. It is used above all where non-pressurized vulcanization makes bubbling difficult to suppress by process conditions alone.

The active ingredient in these agents is calcium oxide (CaO), which reacts with water to form calcium hydroxide. However, calcium oxide is also known to degrade rubber properties, so selecting a grade with the right level of activity for rubber matters as much as the dosage.

The lineup runs from untreated powder through surface-treated and granular forms to a sheet masterbatch, so a grade can be matched to your application and handling environment.