I'm not sure if this is the right place to post a safety question, but here it goes. I made a small forge out of a galvinized oval tub and lined it with a thick layer of a combination of clay and sand. The pipe for the air delivery is black gas pipe and it is attached to the bottom of the tub with pieces of aluminum. The fire in the forge only touches the clay and the black pipe. My question is, is there any danger in using the tub? When it heats will the nickel coating burn off and become dangerous? Also, should I remove the aluminum, even though it is under the clay? I am very new at this, and don't want to make a mistake in the beginning. Also, what is the best scrap material to use in a forge that would be safe and fairly plentiful, and not very expensive? Thank you for your patience and advice.