Hammers (long)

[Delwin D Fandrich]

THEOFONE@aol.com wrote:

> to Delwin Fandrich
>     Is it true that some of the reasons that you gave
> for pre 40's hammers sounding good is, that they didn't wash all of the
> lanolin out of the felt with detergent, and they used mohair at about 5%
> content in the wool?
>     Seems to me, that more time is spent trying to make a cheaper hammer
> over all these years than it would be to make a good hammer. Just
> think of all the man-hours and frustration invested in voicing poorly made
> hammers. No wonder dealers don't want to pay us to voice.
>
>    Theodore Mamel RPT
>     Pittsburgh Chapter

  -------------------------------------

Theodore,

Possibly. I, too, have heard these stories. Although when I asked the hammer felt manufacturers they said no. The processes
have not changed all that much. And the wool available today is no different today than it was in the first half of the
century. At least that is what they say.

I spent a lot of time studying and working with hammer presses, hammer cauls and hammer felt a few years ago. In my own
experience, the two major impediments to pressing resilient hammers are heat and pressure.

The heat is used to set the glues that are currently used to bond the felt to the molding. These adhesives are thermosetting
and most of them require temperatures of about 175º to 185º F. to cure. Once they reach this minimum temperature, they cure
very rapidly. Wool felt is a fairly good insulator so this means that the caul temperatures must be quite a bit higher than
this, especially in the bass where the felt is thicker.

As to why such high pressures are used, I really don't know. I didn't find extremely high pressures to be all that necessary.
The need for production speed is probably the culprit. If production speed were not an issue the felt could be gradually
pressed into the bottom caul as it was with the older hand operated screw presses. (It is the bottom caul that forms the
final shape of the hammer from the shoulders to the crown.) This gave the felt a chance to more gradually conform to the
extreme bending stresses it goes through while being forced into shape. To speed this process up it is usually necessary to
add quite a bit of moisture to the felt. It is necessary to soften and relax the wool fibers. This is done by storing the
felt in a high humidity chamber for some period prior to pressing. Now, anyone who has ever pressed a wool suit can see where
this is going. Combining the moisture laden felt with the heated hammer cauls, the felt is literally "ironed" in the caul.

The result of all of this is that modern hammers coming from high speed presses have much less resilience than do the hammers
that were pressed from the older cold presses. If you take a sharp knife and cut straight down through the crown of modern,
hot pressed hammer, you will find that it opens up very little compared to a cold pressed hammer.

I suspect that at least part of this is in response to the demands of the piano manufacturers who want "bright" sounding
pianos without having to do the acoustical work necessary to get this sound with softer, or more resilient, hammers. Piano
manufacturers also -- justifiably -- want less costly hammers. From the hammer manufacturers point of view, this is the best
of both worlds. By speeding up the process they can deliver both a less costly and more dense, or "brighter," hammer.

Well, again I ramble... Regards,

-- ddf