I'm sorry, but I don't speak French

Sorry,
I said I love the fireplace inside the grey wall.
Which kind of material did you use to build this wall?
Thanks in advance

Sorry but I can't find the previous comment answer regarding the method for finishing. How did you do to have this result?
Thanks in advance

The Castle Creek fireplace used a 1/8" thick steel plate called laser plate. One could also start with a 'pickled and oiled' plate. A material that is without mill scale. The surface was orbital sanded thru to a 240 grit finish. We used the Birchwood Casey product M20 deluted 50% with distilled water. This patina is a solution that includes selenious and phosphoric acids. The diluted patina was sprayed on with misting bottle and worked in with fine Scotchbrite pads and kept wet with the patina until the desired color was reached. It was then immediately flooded with water and force dried with compressed air and towels. Your metal worker can decide what lacquer to best use, there are many that would work I believe.
birchwoodtechnologies.com
ANTIQUE BLACK® M20 IMMERSION
Weggis......looks nice.
Sincerely,
Brent
BRENTON CURTIS METALSMITHING LLC

That is a great FP Nate!!