They were sitting in a room with candle-lit, concrete walls. Is that comma permissible, or does "concrete walls" have to be the noun phrase instead of just "walls"? Please note that if it were "...grey concrete walls," I would certainly not put a comma, because that would follow the conventional order, i.e., colour and then material. But, in this case, "candle-lit" is a compound adjective that doesn't fit into any of the categories of the conventional order of adjectives. Plus, I find the comma separation adds to the ominous feeling of the room that I want, by making "concrete" stand on its own in describing the walls. What do you guys think? Thanks.