Before placing bread or pizza on your firebrick hearth cooking surface, make sure you clean the surface w/ a metal bristle brush - if you use a plastic brush, the bristles will instantly melt (ask my wife…)
Once the surface is clean, blow on the surface w/ a few deep breaths to remove any remaining ash. If deep breaths are difficult - keep a can of compressed air nearby (but keep away from the fire). Blasting the surface with short bursts of compressed air will remove the surface of any lingering ash.
After that, soak an old t-shirt or rag in water… ring all the water out of the shirt / rag and wrap it around your brush. Quickly wipe the firebrick hearth cooking surface - but don’t let the wet fabric sit on the firebrick. A light hit of moisture won’t hurt the firebrick, but if you let it sit on there, it could possibly damage the firebrick.
Wipe, wipe, wipe… then let the firebrick dry for about 30 seconds before you place food on the hearth surface.