Hammers: How much felt over the core?

[David Love]

When shaping new hammers, I always pay attention to how much felt there is
between the wooden core and the strike point through the scale.  I find
this especially important in the low to mid treble where an excessive
amount of felt can seem to swallow the tone.  I use primarily softer style
hammers such as Steinway, Isaac and Ronsen and there is usually a good deal
of filing to be done as the thickness of the felt various considerably from
set to set.   For the most part I do it by feel as the density of the felt
can also vary from set to set, but I generally find myself taking off quite
a bit of felt, especially between notes 50 - 70 on most sets.  I am
wondering if others shoot for a specific target of felt depth over the core
in various sections and, if so, what those targets are.  While the
importance of this dimension seems less in harder hammers such as Renner,
Abel, or Yamaha, I don't prefer that style of tone and so don't generally
choose those hammers (though there are occasions).  Even so, the thickness
of felt over the core even in these hammers varies considerably.   I have
found that if the felt on these softer hammers is reduced to a certain
point, it reduces the need for hardeners (not surprising) and the hammers
develop nicely and relatively quickly yet maintain a stability that isn't
as easily achieved with either hard pressed or lacquered hammers.  So, I'm
curious if others have found a specific target that they have found be
optimal and on which kind of hammers.  

David Love
davidlovepianos@earthlink.net