It may not be the hammers. Pluck the lowest steel wire tenor string then pluck the highest bass string and compare the tone. If the bass is softer try twisting the string. Other problems could be the bass bridge is loose from the soundboard. To get good tone out of the bass might need new bass strings. <div class="gmail_quote">On Sat, Nov 17, 2012 at 5:47 PM, David Boyce <<a href="mailto:David@piano.plus.com" target="_blank">David@piano.plus.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <div bgcolor="#FFFFFF" text="#000000"> I don't have much experience with using laquer etc to harden hammers, and I am looking for advice. A recent example typifies a situation I've encountered before. A client has bought a large good-quality upright, about 80 years old. The bass hammers are rather soft. They are not deeply grooved. I have ironed them, but this produced only minimal improvement. Obviously the proper solution is to fit new hammers. But where cost is a factor, what could I do to harden the existing hammers. What is needed I think is not to make the surface harder but to make the overall texture more dense. What would be a method to do this at minimal cost? Advice will be most welcome. Best regards, David <a href="http://www.davidboyce.co.uk" target="_blank">www.davidboyce.co.uk</a> </div> </blockquote></div>