<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 5.50.4134.600" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV> 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 = 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. 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.</DIV></BODY></HTML>