Hammermaker's corner 7.

[isaacah]

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HAMMERMAKER'S CORNER 7.



ARI ISAAC.







At this point my luck, or was it my persistance began to change and to =
produce better results. I had to give up on ordering felt from =
Whitehead, Royal George, because their quality went way down while their =
arrogance remained as British as ever.

I called a company called Bacon in the U.S. and got. nowhere. The first =
response I got when I told them about my ideas for the sheets of hammer =
felt I wanted was

"We'd need an order of 1000 sheets to implement the specifications you =
want".

So much for that. I had to learn the tough lesson not to give up without =
more than one try. I had laid out my ideas to them and left it at that. =
One day I get a call and it is Mr. S. their felt expert, with whom, =
previously, I hadn't been able to connect, he was asking me what they =
could do for me, I couldn' believe my good fortune. Here was a man who =
knew felt and who understood what I was saying to the small detail. The =
felt sheets I began to receive were beautiful. First, they produced a =
musical tone right out of the box. Next, their tone remained stable and, =
this I found out later, these hammers had a longer life span than =
anything else out there.

Mr. S. told me that in the 1920s wool for piano hammer felt was picked =
according to criteria no longer used. One of these criteria was the =
region the wool originated from. Another was the quality of the pasture =
in the region for a given year. Another, this one important, is =
bleeching the felt. I told him I never would used bleeched felt as the =
bleeching removes even more of the wool's natural resilience.

My idea of graduating the felt density from bass to treble turned out to =
have an added advantage, one I could not have known about. As the wool =
grade fiber becomes thinner - a longer fiber is needed to felt =
successfully. The longer the fiber - the more efficient the spring in =
the hammer.

Now it was time, I felt, no pun, to determine the precise rate of =
density graduation in the bass to treble axis of the sheets I would use =
to make Isaac Cadenza hammers.

There are two measurements to be taken: durometer hardness and creep. =
The first, durometer hardness, is the measure of surface hardness where =
glass =3D 100. Many hammer makers try for 90/95 durometer in the extreme =
treble of their hammers. Hardness, as a measurement is useful but a poor =
indicator of tonal quality.=20

A durometer consists of a blunt pin (about .045" diameter) attached to a =
gauge and pushed by a spring. This pin protrudes from the bottom of a =
weighted box housing the gauge. The durometer is set on the face of the =
sheet of felt and for the hardness reading the surface resistance is =
measured. Creep measures the time it takes for the fibers adjacent to =
the point of the spring loaded pin to allow the pin to penetrate the =
surface (or not). Measuring a sheet of glass will allow no penetration. =
The pointer measuring creep will not move. When measuring, say, soft =
foam, the penetration will be very quick and deep (pin sticks out not =
much more than 1/16"). The creep measure, the number pointed to on the =
gauge, will be low indicating a very low resistance to the pin's =
penetration by the surrounding material. When measuring the creep on =
hammer felt used for Isaac Cadenza hammers the creep pointer will =
indicate a number that is high and the pointer will move very slowly =
indicating a resistance of the area immediately surrounding the =
protruding pin. Measuring hammer felt the creep is a far better =
indicator of felt spring, resilience, than durometer hardness.


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