Once hammers are nicely profiled* they can be ironed. Ironing is not merely cosmetic: it ties in the exposed fibres, protecting the felts from dirt & dust.

*Ironing can also be used as a temporary (and very mild) way of firming up the hammers and the tone – especially when a piano is in a humid environment. In this case, the iron is drawn over the hammer sides.

front & back

pressing on a hot iron