Sometimes (as here on this Blüthner concert grand) new hammers are glued on, fitted only approximately to the strings and, it seems, the piano shoved out the workshop door – as if that were all that needed doing…. But new hammers need profiling just as much as worn hammers do (with much finer removal of felt).
This is because, if glued on simply as they arrive from the hammer manufacturer, the felts will remain bowed. And this is because hammers are cut, core wood & felt together, from one long piece. The release of tension across each hammer’s width as it is sliced off the long piece allows the felt to bow upwards, leaving each hammer looking as if it has ears.
The consequence of this is that the hammers do not meet the strings with their full surface area, striking the strings with less than half their potential power. Thus the piano seems weak, is not played much – and a vicious circle ensues wherein the hammer felts never reach their proper performing consistency due to not being struck hard and frequently enough.
In this picture, the hammers to the left are as I found them (fitted and unprofiled – with ‘ears’), those to the right are profiled to give level noses.
NB The profiling was only done after the hammers were travelled & burned and correctly fitted to their corresponding strings (see next blog ‘Burn The Hammers You Don’t Like!’)