Pitch/Cerrobend/Ice for Tube Bending.

You don't need to worry about this. This is a maker's choice and a maker's problem. All you should have to worry about is how well and accurately the bends are executed on your horn. I don't know why makers spend so much time arguing about process when it's really the product that matters. Using bending medium to distinguish one horn from another seems silly to me.

If, after all that, you are still curious as to why I use pitch, I'm happy to explain.


By now, you probably know well enough that I generally do everything in as inconvenient a manner as possible, as a matter of course. Pitch has an optimal bending temperature window of TWO degrees. It's also very susceptible to overheating which can burn out some of the components and make it soggier. It bends differently in the summer than it does in the winter and requires recipe adjustments to compensate. It makes an epic mess and is the only thing in the shop to ever injure me enough to scar. Believe me, I would love for it to not be the best, however:


It's true, there is a reason it's been around for so long. The trouble is, most people don't learn it well enough to be able to use it properly. Thankfully, I spent three years with Rick Seraphinoff who had already spent twenty years using pitch, so at this point its like I've been using pitch for thirty years. Pitch allows a good maker to accurately place angles and geometries in a bent parts and also make fine adjustment in ways other methods simply won't do.


Traditionally, makers would burn the pitch to ash after emptying and thus anneal the tube to make sure it was clean on the inside. However this is NOT necessary. Silver chasers used pitch to support their work for hundreds of years and yet removed it without burning it. I use a similar technique to remove pitch from the insides of tube without annealing. This gives me full control over the final temper of the material and lets me use lower temperature heat treatments to get my desired sound quality.


The stiffness of brass and the stiffness of pitch cooperate to determine the quality of the bend. This is more useful than you might think. Pitch is not a completely solid material, it is the ultimate non Newtonian fluid. The right stiffness of brass in combination with the pitch at the proper temperature and proper mixture preserves the roundness of the bend as the brass is being worked. So, I can feel in my hands how the material is bending and know that the brass is not being stretched and strained more than is wise. Cerrobend is much less subtle and since the bend alloy is so much stiffer than the brass, it's possible to overwork the brass and invite stress fractures as the horn ages.


Frozen water mixed with a little bit of soap to prevent crystallization is about the most convenient solution imaginable. It empties itself out as it melts and is clean to work with. This is a favorite process with large manufacturers, HOWEVER, industrial bending almost always uses a "blow out" mold to restore the roundness of a part. They do not expect the ice mixture to hold a perfect roundness tolerance, they use a large hydraulic press to expand the part into a steel mold and make a part round again. Obviously, I could never fit all that stuff in my shop. Another downside is that the shape of the part is determined 100% by the shape of the mold and I've never seen anyone make molds that were good enough to make parts that could use the long jointing techniques that I favor. Additionally, finding a freezer cold enough to freeze the ice as hard as it need to be is a challenge. Often times an alcohol bath or even liquid nitrogen is used. No thanks.


There are appropriate uses for every bending medium and certain people like to use different ones. I like to use pitch and I'm good at it; Keith Berg likes Cerrobend and by all accounts is good at that. If a bend is well done and has the temper that the maker intends, it doesn't matter what medium they use!..... but pitch is still the best :)


September 13, 2017