A 42-year-old male painter presented to our facility with superficial and partial-thickness burns to his face and both arms. He had been in his usual state of good health until the day of admission, at which time he was power-sanding old bathtubs in preparation for repainting them. Because this activity generates large amounts of dust, he routinely worked with the bathroom door closed to avoid contaminating each apartment.Using his electric sander, the subject began sanding a bathtub in an apartment that had been vacant for more than a year. Suddenly, a ball of orange fire engulfed him, accompanied by an explosive sound. In an instant, the fire disappeared as quickly as it had begun. Startled, the painter looked down and saw that his sander was still grinding away in the bottom of the tub. Reaching down to unplug it, he noticed a little ring of blue flame, "like a stovetop burner," surrounding the bathtub drain. He blew on the drain and extinguished the blue flame. He stood up and was surprised to find that the bathroom door had literally been blown off its hinges by the force of the explosion. Finding the hairs on his arms singed, he left the vicinity, ran water over his arms, and then sought medical attention.On admission, he was found to be a healthy 42-year-old man with superficial and partial-thickness burns on his face and both arms that were worse on the right than the left. A clear demarcation of burnt from normal skin was observed at the level of his shirtsleeves, as well as the clear outline of his facial dust mask (which had protected his mouth, nose, moustache, and chin). The patient had no evidence of blast injury.Operative débridment revealed that the burns were superficial partial thickness. Biobrane ® (Bertek Pharmaceuticals Inc., Morgantown, WV) was applied to the affected areas, and the patient recovered uneventfully.