A common concern/complaint we run into while touring our lovely City of Toronto tuning pianos is heavy touch. Some keys or entire pianos may respond poorly and require a great deal more effort to play/depress than others, making it nearly impossible to play the instrument smoothly and with the intended intonation and feeling. While this is especially prevalent in newer pianos, older, more “worked-in” instruments are not at all immune to this problem, as the causes of heavy touch can be numerous, from the length and weight of replacement hammers, their age and stiffness, to regulation issues such as overly tight pins, residue buildup in action parts (this being more common in older pianos) and simply improperly repaired or rebuilt pianos. But in the end it comes down to what’s known as “touchweight”, i.e. the weight necessary to depress the key, which is now most commonly assessed in grams.
While many older pianos and those direct from the factory often have a higher touchweight (in the neighbourhood of 60 grams), the internationally accepted standard these days is 49-50 grams. This weight is assessed using a gram weight placed on the end of the key while the right pedal is depressed to disengage the dampers. Weights of varying heaviness are added or removed until the key depresses slowly under the given weight.
Only if and once any of the regulatory causes mentioned above have been cancelled-out, the issue is then most commonly resolved by adding or moving key weights/leads, which are implanted into the keys themselves. These typically range in size from 10-12 mm and start at 6.8 grams. Adding these weights before the piano has been properly regulated/aligned and eased can do more harm than good – a mistake not uncommon among inexperienced technicians.
These are strategically embedded along the key until the desired touchweight is achieved. In some cases existing weights are shifted to new positions, with the old holes filled in.
If done properly, the keys should be capable of rising back into position on their own with a 29-30 gram weight placed atop. In rare cases there may be no room left to add additional weights, at which time other tricks of the trade can be attempted, such as altering capstan screw positioning.
Due to the considerable time and expense involved in altering a piano’s touchweight, this is a procedure we typically only recommend for higher-end, name brand grand pianos such as Steinway & Sons, C. Bechstein, Bösendorfer and the like.