Over a period of years, the action in a piano becomes sluggish and the reason can usually be attributed to the binding of the centre pins with the cloth bushings in their associated flanges. The problem can be likened to the piano equivalent of arthritis. The action becomes more and more sluggish as the years go by, with many notes not playing at all, in particular when the jack fails to return under the hammer butt. The best remedy is to strip down the action and recentre all the flanges, the procedure of which covered in some detail in Action Recentering elsewhere in this technical section page.
To avoid the expense of centre pin replacement, lubrication can be used as an alternative to temporarily free up the moving parts of the action. While this will never prove as effective long term as a proper recentering job, it may save the day by allowing the pianist to use the instrument in the meantime. To determine the effectiveness of various lubricants, I carried out a test using four different types: Protek CLP, a widely known but rather expensive lubrication manufactured in the US, Heckscher Pin Lube from the UK, WD-40, a silicon based domestic lubricant (Shock Horror!), and finally, water. While the purpose of the first three solutions is to provide lubrication, the application of water cleans the bushing cloth and to some extent the pin, causing the cloth to initially swell much more than the other lubriants thus causing the joint to bind, but then shrinking again after drying, leaving the flange freer than before.
Several hammers were removed from an old upright piano action and five were selected (one for the control) that showed to be almost totally seized when held by the flange and swung. Each was then labeled with the type of lubricant that it would have applied. The hammers were then
immediately tested by swinging, again 30 minutes later, again after 6 hours and finally after several days. The results at each stage were noted, and a further application was then made to each hammer, identical to the first.
The following results were observed:
WD-40 was the most effective but left the flange greasy, making a permanent repair at a later stage difficult, not to mention the potential attraction of dust. 30 minutes after the second application, maximum effectiveness was reached.
Protek CLP proved to be most effective immediately on application, reducing after several hours, but then finally reaching maximum effectiveness several hours after the second application. Its effectiveness in terms of amount of swing radius was about 30% less than the WD-40 hammer.
Heckscher Pin Lube was barely effective on application and despite a slight improvement after 30 minutes, ended up at the end of the tests to only half as effective as Protek.
Water as expected caused the flange to seize immediately when applied, but freed it up as much as the WD-40 did once it evaporated after 6+ hours. Strangely, after re application, the effectiveness reduced slightly, but the difference was considered be negligible.
When comparing the above hammers with the untreated hammer flange (control), it was clear that all four solutions were effective in freeing up to some degree the sticking flanges. Because of the greasy residue left by WD-40, it should not be used as a lubricant on piano actions, even though it proved most effective in the test. The reason for its inclusion in the test was to see if indeed it was any way effective - which it was! Heckscher Pin Lube is almost completely ineffective and I would not recommend wasting the time applying it to any work. While water may be ultimately give impressive results, I have reservations on the long term effect it may have on the piano parts and would only consider using it if no alternative lubricant was available. Also because of its non viscous nature, water is difficult to apply. When taking all factors into account, Protek CLP could be considered as being the best choice, with a second application several days after the first in order to get the best results. Furthermore, this brand can be used with confidence, knowing that it is widely regarded as being an acceptable product in the trade. BH