-the felt on your piano hammers.  The make-up of the felt, and how it is mounted onto the wooden molding to make the complete hammer, will determine every facet of the tone of your piano. There are primarily two ways of making felt out of sheep's wool; pressing and felting.  A layer of wool fibers, along with the introduction of steam and soap, are pressed between two plates for a given length of time and at a given pressure.

For the purposes of hammer felt, the layers are thin (about 1/16") and a number of layers are pressed together to make up the hammer felt sheet that will be cut into strips to make up the sets of hammers.

To make a sheet of hammer felt by felting, the wool fibers are worked into one another by the action of mechanical fingers before pressure is applied.  The resulting sheet no longer has any layers.  The fibers in the felted sheet are, for the most part, in three dimensions while in the pressed sheet the fibers are for the most part in two dimensions.

The wool fibers in the pressed sheet are subjected to some felting but are more compressed.  The fibers in the felted sheet are mostly felted and subjected to some pressure.

The felted sheets of hammer felt made for Isaac hammers function like a spring due to the three dimensional positions of the wool  fibers throughout the sheet.  It is the spring in the felt that produces the power, the bloom and the long sustain, at every volume level, typical of Isaac hammers.  Many other hammers rely on a heavy application of chemical hardeners and a lot of needling the hardened felt to achieve their results.

Because of their endless tone colour range, Isaac hammers will make the music you play sound so much better, so much more like you want it to sound.  And without the potentially destructive, heavy reliance on hardeners and a lot of poking the hammers with needles. The specific design of our felt sheets, combined with our unique process of stretching the felt around the wood molding, gives Isaac hammers superb tone quality and a far longer life than most other hammers available on the market today.