How to add more "punch" to the treble of a grand piano

A recent customer commented that they would like a tad more “punch” in the treble section of the Yamaha C7 that they came to view, so I’m building this article by asking my 5 favourite piano technicians to share their thoughts on this challenge.

Here are the comments I received in order of who replied first:

My friend, Gordon from Aberdeen, emailed me with this comment:

Deep toning on the shoulder would create more depth and setting the nose of the hammers to the strings would gain slightly more power.

Then Barrie replied. Barrie has been an invaluable friend and mentor to our little piano shop since our very earliest days tip-toeing into the piano trade. Here are his comments.

There are different approaches to making the top trouble sing more. All depends on the state of the hammers.

• Step one: Reface the hammers if necessary [comment from Mark: refacing is a process of improving the shape of the existing hammer using sandpaper]
• Step two: Use a hot iron to iron the hammer noses.
• Step three: If both of the above don’t work, you’ll have to juice them with a hammer-hardener of your choice.
  On some Pianos using long needle just passed staple towards nose of the hammer releases some of the tension of the felt, making the nose of the hammer hard. That tends to work well in the mid range and bass, not so much the top treble.
  There is one other thing, you should always check the frame bolts. Sometimes they need a quarter-turn that will increase the down-bearing slightly and improve the overall tone of the piano. You must do these in sequence.

Then our in-house technician, Peter Saddler-Eastwood replied saying:

- Ensure the hammers are at optimal shape to deliver a precise strike
- Ensure the hammers are aligned perfectly to the strings and adjust the action in and out to give the optimal strike point.
- Reface the hammers with a high grit paper to close the grain of the hammer felt
- Ensure the regulation is set to deliver maximum power and clean escapement to make sure the hammers clear the strings efficiently as possible post strike.
- Finally, hammer ironing or doping to further brighten the tone of necessary.
(I hope this is enough, it’s a rich and complex subject which doesn’t lend itself to short answers I’m afraid!)

In my own reading of the subject today I stumble across this very interesting thread on the PianoWorld forums where Chris Chernobieff from https://chernobieffpiano.com/ warns techs against using a common solution called B-72 to make hammers harder / brighter. Instead, he shares his own decades worth of experience to recommend a less aggressive solution that achieves a superior tone. Here are some of the highlights from his comments taken from this thread

When i started using chemicals for piano hammers (back in the early 90’s) all that was used was lacquer. The problem with lacquer is that it’s too brittle and leaves a ping sound

Enter B-72. [paraphrased]
At first i was excited about B-72, but now i have removed it from my toolkit.
Its problems are that it is hard to dilute, and that when dilute it with alcohol, the water contained in the alcohol fights against the hardening result that you want, and the tone ends up not as pure or clean as you want.

What i now use is just two natural resins. Sandarac and Shellac. Nothing artificial or plastic […] I apply to both sides. Sometimes 2 passes. I do this after listening to hammers that don’t reach a fortissimo on a hard blow. I am also working between hammers that already sound great, and those are my targets, which prevents overdosing. […] The secret to using the shellac is to basically thin it as much as possible. […] Generally, the bass hammers just need a light spraying of store bought spray shellac to add some growl. With the tenor break being the trickiest to work with depending on the make and model. In the 5th and 6th octaves i apply one drop of the light gold to each strike point and it should soak to about half the distance if diluted correctly. This way there is a perfect graduation from wood moulding through the sandarac and shellac to the surface. […] In the set i’m working with now, i’ve used so little product (just a few very diluted drops) and with such a big improvement, i guess it was kind of an eye opener for me. […] When i went from using B-72 to a very diluted shellac i can’t emphasize enough how much more beautiful the tone was. Shellac is soooo much easier to use than B-72.

More to come…