FIREFLYMastic is a water-based acrylic sealant.

It is used to seal around services and to adhere FIREFLY Penowrap to substrates and FIREFLYBatt. The Brush Grade is specifically designed to coat the cut edges of FIREFLYBatt before rejoining them around service penetrations. Once FIREFLYBatt sheets are installed, FIREFLYMastic is applied to fill small gaps and holes, ensuring a complete seal around services.