You can’t use a brush for this: they’re already perfectly good at depicting the truth. You need a fountain pen.
Cardiff pumps the lever and drenches the halogen bulb in ink, which mostly steams or drips right off: the smell is oily and redolent of mushrooms. He empties cartridge after cartridge, and some the residue begins to build up. It dims.
When it’s thick enough, he can take off his dark goggles and look directly at it. The dry shell has already started cracking; Cardiff waves his fingers slowly over them and watches their outlines flicker like lightning on the wall.