ignition source of moderate intensity such as may contact insulation installed in residential buildings for example a wiring hotspot the back side of a recessed light fixture or the metal surface of a heater or furnace flue the burning of the cigarette and the specimen is allowed to proceed undisturbed in the test sample for at least two hours or until the smoldering is no longer progressing after completion of the burning the specimen holder is weighed and the percent loss of the original specimen is calculated the degree of charring is also measured to the nearest half centimeter acceptable levels for weight loss and charring distance are judged to be respectively less than 15 of the specimen weight and no charring within 4 cm of the sides of the specimen holder clean test coupons of aluminum copper or steel are placed on presaturated portions of cellulosic insulation material inside a crystallizing dish additional presaturated portions of cellulosic material are then placed on top of the metal coupon and the composite is tamped to assure an even distribution of the material and good contact of the insulation with the metal as well as the elimination of air pockets next to the metal coupons crystallizing dishes are then placed in a humidity chamber preconditioned to 48 9 u00b0 u00b1 1 7 u00b0 c and maintained at 97 u00b1 1 5 relative humidity the specimens remain in the chamber for 336 u00b1 4 hours upon removal from the chamber treatment the composite specimens are disassembled thoroughly washed brushed to remove the loose corrosion products.