1. Choosing the drum
The drums used for steel pan making are ordinary, new or used steel barrels. The volume of the standard steel drum is 208 litres (which equals 45.8 imperial gallons or 55 U.S. gallons, respectively). The drums are 59.5 cm (23 inches) in diameter and 84 cm (33 inches) long. See appendix D for more details on drums.
Panmakers usually prefer drums that have a rim with a flat side and a square cross-section a so called "flat fold". A new method to join the side and the bottom of the drum is to make a round fold, see fig. 1.1. Some panmakers avoid drums with this round rim, because they claim that it will not withstand the stretching forces during the sinking. However, recent tests (done by a tuner and myself) indicate that the round rim is as durable as the flat rim.
Acoustically, the result seems to be acceptable too. On Trinidad, backline instruments are often made out of round-rim drums nowadays, but the round rim seems to be avoided in front line instruments, I belive, mostly for aesthetic reasons.
Fig. 1.1 Cross-section of the traditional flat rim and the new round rim.
The thickness of the metal is of vital importance. Generally, it seems to be better the thicker the metal is, especially for the lower tuned instruments, such as bass, cello and guitar pan. But if you use a thick metal for the higher pans, such as the tenor and the double tenor, the small high notes might be difficult to tune. The thickness of the steel in the bottom of the most commonly used drums is 1.2 mm (18 gauge). The side of the drum can be either 1.2 mm or 1.0 mm (20 gauge) thick. It is unclear which is the best a side with 1.0 mm thickness seems to be most common. The thinner skirt will probably give the sound of the pan a better "ring" than the thicker one.
The thickness of the metal in the bottom of the drum can not be measured directly without destroying the drum, so you have to use some tricks to determine it. The thickness of the metal in the bottom and the top can be assumed to be the same. The thickness of the top can be measured with a tool that is put in through the tap. The weight of the drum and the sound that is emitted when you tap on it can also be used as clues to the thickness of the metal. See appendix D for data on the weight of different drums. Drums with less than 1.0 mm (more than 20 gauge) thickness in the side are often corrugated for additional strength. Try to avoid those for pan-making because the bottom of these drums is probably too thin (1.0 mm or less).
The material of the drum should be mild steel. Steel drums with a galvanised iron coating can not be used for steel pans - the coating definitely spoils the tone. The quality and homogeneity of the steel are important. Poor metal may have spots where the carbon content is more concentrated. These spots are harder and may burst when stretched during the sinking.
The condition of the drum is also of great importance. A little light rust here and there on the surface doesn't matter, but try to avoid drums with sharp dents and spots of rust that seems to be going deep. Such spots tend to crack when the metal is stretched during the sinking. Text that is grooved on the bottom of the drum will usually not affect the result as it will be smoothed out during the sinking. But if the text is deeply grooved and has sharp edges, try to find another drum, at least if you are about to make a pan that is to be sunk deeply.
Some drums are "re-conditioned", which means that they are cleaned and used a second time. The drum is often burned clean during the reconditioning process and this affects the metal in an unfavourable way. Try to avoid these drums. Re-conditioned drums can be detected by scraping off the paint at a spot and looking at the metal surface. If the metal is clear and shiny, it is a new drum. If it is grainy and without lustre, it is re-conditioned.