Can the MORTEX® coating be applied on fireplace mantel or open fire?
The MORTEX® can be placed on the flue wall of your chimney, the temperature must not exceed 40-50°C.
There is no specific preparation required for your chimney flue but well one specific to your substrate.
If the substrate is porous and mineral, the suitable primer will be the Residur.
Varnish or oil protection is possible.