The heat in the vulcanisation process causes moisture in the rubber material to generate bubbles.
Dehydrating agents are necessary to prevent bubbles caused by this moisture.
This is particularly used as a measure to prevent air bubbles during non-pressurised vulcanisation.
On the other hand, calcium oxide itself, the active ingredient in dehydrating agents, is generally known to reduce rubber properties, so it is advisable to use a dehydrating agent with a suitable degree of activity for rubber.

VESTA is a dehydrating agent (anti-bubble agent) made from calcium oxide, which has optimum activity as a dehydrating agent for rubber.
It also improves dispersibility in rubber through various surface treatments and masterbatching, and is effective in preventing scattering during roll operations.