Now I'm not an expert on this, but my limited experience tells me that the process of scorching fractures the surface and that the fractured areas of charring become loose. I fear that sealing the surface will be a temporary solution because sooner or later, 'plates' of scorched and charred surface are going to part company with the substrate.
It's a bit like putting Selotape on a dusty surface.....the Selotape sticks to the dust, but the dust eventually parts company with the surface beneath it!
Les