Burning

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Burning the Pan

Once the pan has been shaped, its time to burn it. I generally burn the Leads and Seconds on a wood fire, and do not burn the cellos and basses other than with a blow-torch on individual notes as required. I've made a few leads which I did not burn on a fire at all, but just used a blow-torch on, and they came out fine.

It's common for me to burn a pan on a fire and then still have to individually torch a few notes.

It's a long-held misconception burning a pan "tempers" the steel. The term "tempering" means all kinds of different things. The effect of heating steel is quite varied, and is affected by the steel composition, the temperature, the duration of the temperature, and the rate at which the steel is cooled.

The measurements I've done with infrared thermometers show that on a gas burner the pan only gets up to about 450F at the hottest point. This temperature basically is hot enough to only "stress relieve" the steel and not affect its hardness very much at all.

On a wood fire the pan undoubtedly gets hotter as parts of it can be seen to be a dull red color, which would indicate its in the region of 700F - just above the "tempered martensite embrittlement" range, which increases toughness but actually makes the steel weaker.

Its my experience that pans burned on a wood fire have a brighter tone than pans burned on a gas burner. This is consistent with the science of tempering which shows that higher temperatures cause the steel to harden. I've also found that burning cellos on a wood fire makes them have an overly bright tone, and not the warm, rich timbre that I prefer. Consequently, I do not burn my cello pans at all but rather use a blowtorch on the individual notes.

To burn the pan on a wood fire, I use a standard Weber charcoal grill with a 2" wide metal T-piece laid over it for the drum to rest on. I burn the drum for about 5 minutes - essentially I wait until the entire bowl has turn a deep blue color. Then I remove the pan from the fire and let it cool on its own. I've found that spraying the drum down with water to cool it quickly affects the pan adversely.

Basic Weber Charcoal Grill


(Above) The metal T piece laying over the grill. This is made from 2" wide by 1/8" thick steel. The connection is made with two bolts. One day I'll get it welded together.

(Top Right) A pan being burned, just starting to change color.

(Bottom Right) The color of the steel that I like before I take the pan off the fire.




Using a Blowtorch

I've found that the use of a blowtorch can be vital to achieving a balanced sound on a pan. On a Lead Pan or Double Second, it can make notes ring better and sustain longer. On a set of Cellos, it can help make the notes move more freely and "breathe" better.

I usually start at the "bottom" of a note - the part closest to the center of the pan - and work around the left edge of the note, and then the right edge of the note. I only stay on the steel long enough to make it turn blue - the flame will actually be slightly ahead of the blue steel area. I don't let the flame just sit on one spot for a long time. I also work only on the edge of the note, never on the inside. I also never use the torch on the steel in between the notes.


A mistake I made



When I was first making pans in South Africa in the 80's, I had no reference material other than the jacket notes on a couple of 33 RPM LP's. Of course, these were of limited value, but they all talked about tempering the pan and getting it cherry red. The fires I was burning my pans on were not even close to this temperature, and since the pans weren't working well, I blamed the fire....

To solve the problem I designed a burner that would do this. Essentially, its an industrial extractor fan that forced air down the barrel from the right. The air went into the chimney arrangement and was directed upwards through a metal grill/grate on which the fire was made. The pan rested on two rails mounted over the fire. There was a skirt around the outside of the chimney that directed the flames upwards and parallel to the skirt of the pan.

It did a fantastic job - I could get a pan cherry red in about 3 minutes. When I took the pan off the fire and laid it on the ground, if the surface was not flat the rim of the pan would actually distort as it cooled down!

Of course, the pans didn't sound any better, the real problem lay in the shape of the bowl that I was making. Once I got better at making the pans themselves, I went back to a regular wood fire; I found that burning the pans this hot actually made them sound worse, not better.
Once I've burned around the outside of a note, I cool the note with water immediately. The only exceptions to this are high interior notes, above about F#5 on a Lead Pan; I usually tune those while they are hot.

This is the propane torch that I use. I've used a MAP gas torch too, but the temperature was very high and the notes physically distorted, and there was no improvement in the sound. Beginning to burn a rim note. I constantly juggle the setting on the fuel flow to make sure that the flame is consistent. It's also easy to let the flame extinguish itself if you get it too close/too far from the surface. Moving around the note. The irregularity in the width of the burn is due to me stopping to take photos while burning the note. Once I get to the rim, I will go back to the bottom of the note and go around the other side of it. Water lying in the pan after I cooled the note I had just burned. The two notes to the right show how even of a burn pattern one can achieve.


VERY IMPORTANT While burning a note can often improve the sound of a note, it is not going to magically fix a poorly shaped note. When you burn a note and cool it, if everything is set up properly, the pitch of the note will go sharp by about a tone. The retuning process from here should be a matter of less than a minute.

If you burn a note and it "pops" when you cool it, there are major issues with the boundary of the note, or there is too much material trapped inside the note (see sinking/shaping issues). Notes like this need to be fixed by being properly shaped or prepped; no amount of burning is going to help.

If the note goes FLAT after being burned and cooled, this is slightly less of a problem than the pop. However, it still points to issues with the boundary and shape of the note which should be addressed prior to retuning.


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