THE BASICS OF FUMING If you are not familiar with how a true fumed finish is produced, here is a brief oudine of the procedure. A clear plastic tent with a timber frame is erected in an outdoor location to house the workpiece during the fuming process. Household ammonia can be used, but it is a very weak solution that only contains about 5 - 10% ammonia. Professional The lop half of the upper panel is fumed with 26% ammonia for 5 hours; the lower half of thai panel for 10 hours. The bottom panel shows the further darkening from a top coat of tung oil. finishers use an "industrial strength" 26 - 30% ammonia solution, which can be obtained at some office supply or blueprint supply stores. The work is first placed inside the clear plastic tent, and then small plastic or glass containers with covers are spaced evenly around the inside the tent. Ammonia is then added to the containers. You will need to construct the tent with a door or a flap which can be opened and closed so that you can reach inside the tent when you fill or refill these containers, and then be able to seal up the tent to keep the ammonia fumes inside.