Cleaning Copper Wound Strings

Cleaning Copper Wound Strings

Over time the copper wound strings on a piano develop a dead tone. Impurities lodge between the windings which cause the strings to lose their flexibility. The normally bright coloured copper gradually turns black, which comes off in a form of powder similar to soot, when touched. In certain Rotorua (NZ)  areas, where sulphur is a product of the local geothermal activity, the reaction from the sulphur can affect the strings so badly, the bass section becomes unplayable. When a bass string is removed from a piano, it can be so stiff, it can be held upright without any bending whatsoever!

I have had to rescue many pianos from this fate, and their are two options open to the customer. Firstly the affected strings can be replaced by a new set, which is what I would normally recommend but is the most expensive. Alternatively the strings can be restored by cleaning and then replaced. The former method is a fairly straightforward procedure which is covered in many manuals. The restoration option however is not so straightforward and it is the purpose of this paper to explain how it is done.

If the piano is to remain in a particularly bad sulphur area then it may make better economic sense to clean rather than replace the existing strings as they will be back to the same condition within five years (even with new ones). The options are first given to the customer. If they choose to have the old strings cleaned, I always tell them that only about 75% of the tone is likely to be restored. Often it is more, seldom is it less.

To remove all the wound strings takes about an hour and a half and is a dirty job. Old clothes are required, along with spare cloths and newspapers.

The action is removed and even the keys if necessary to allow the best possible access to the strings. The tuning pins are turned - usually no more than one revolution - until the coil just starts to buckle. No further, otherwise the string may break at the becket. I have a tool specially made for me that lifts the coil off the tuning pin very effectively. A blunt screwdriver, pliers and a string hook are also used as required. There is quite a skill in removing and replacing strings, often having to alternate between all four tools for some coils. Despite initial hesitation through reading various texts, I have been assured that the piano will suffer no damage due to unequal tension. My experience has certainly not revealed any sign of the piano suffering in this respect.

If the piano has an agraffe, such as in a grand, I do not attempt to pull the strings through but rather, clean them while still in the piano. I have been told by other technicians that it is quite in order to pull the coil through the hole in the agraffe, but I believe that the coil could be damaged and then break at the becket. Cleaning strings that are dangling out of a customer's piano in their lounge is not an ideal scenario, but I have done it many times, taking every care to use appropriate covers and towels as required. Accidents are simply not permitted to occur!

If the strings are removed, they are threaded individually on to a coat hanger wire in the order that they are removed, and the ends of the wire securely joined so they don't slip off and get mixed up. The strings are then slipped into a paper "Kleensak" and taken away for cleaning.

Note. If it is decided that a new set of wound strings should be ordered from the manufacturers, it is essential that the piano serial number is quoted along with the model. The wrong size strings were sent to me once and it was discovered that the piano manufacturers had altered the stringing configuration part way through the production of that same model. The strings were too long causing the windings to extend over the hitch pins. Because I had initially quoted the piano serial number - which they had not checked - they were obliged to replace the strings with the correct set, at no additional cost.

Cleaning. The strings are hung outside on a clothesline and simply hosed down. This will get rid of a large proportion of the black residue. The strings are separated as best as possible - which is extremely difficult due to the coils catching on each other. A bucket of hot water is then splashed over them, immediately followed by a liberal dose of caustic spray such as oven cleaner. After a few minutes the strings are hosed down and if strings are particularly bad, the process is repeated. The residue that comes away from the strings has to be seen to be believed.

Each string must now be cleaned with a domestic scouring pad such as Scotchbrite. The string is dragged through the pad so as to remove as much as the residue as possible. Be aware that some of it may not come off. This delightful activity takes about half an hour and is then finished off with a final hosing. The strings are left to dry and any rust appearing will only be superficial. They will have a dull pink appearance. Actions such as hosing down obviously cannot be performed while the strings are in the piano, but the use of buckets and rags will do the job. This all sounds rather crude, but the whole business can be done effectively and professionally, without as much as one drop of water going where it shouldn't. See the result in the Gallery section!

Refitting and pulling up. This usually takes me just over two hours. The strings are fitted onto the piano in the usual way. Care is taken to remove them from the hanger wire in the correct order, always from the same end of the wire (a mistake can easily happen here, when there are only two or three strings left on the wire). Each coil should just nicely fit back over the tuning pin which is turned so the hole precisely lines up with the very end of the string without having to re-bend the becket causing it to break. For the end to go properly in, I find it essential to have the hole lined up exactly.

Once the coil is over the pin but before the end is put though the hole is when I twist the string at least one complete turn in the direction of the copper winding. This can be tough on the fingers and if necessary, I will use a set of vice grips down by the loop (but not over the windings) to help matters. The twisting described substantially improves the tone and eliminates any rattles.

Fitting the eyelets or loops on to the hitch pin down below and then getting up to fit the coils over the tuning pins is regarded as my exercise for the day. I steadily work my way through to the bass section without being too time conscious as there is simply no shortcut method. With the aid of a blunt screwdriver I tap the loops so they are seated at the bass of the hitch pin. The welcome rest can now be used to assess how well everything has gone so far and to tidy up the coils (including properly seating the beckets) which should look just as they did prior to removal. It has taken a lot of practice to develop the technique of refitting.

The strings can now be pulled up and an overall tuning considered at this stage (see my article on pitch raising). New and replaced strings stretch considerably so I would expect to have to call back about three times, with a fine tuning done on the final visit. The customer would be told that further string movement will be noticed a few months after that.

The above callbacks including the final tuning are included in the price as I regard them as being part of the re-stringing job. Not to do this would be unethical.

The process from start to finish takes me a good six hours so would be charged out at around $600.00 (2008). The tone is always dramatically improved and my customers always regard the expense as being well justified.

Brian Holden, 2008

Letter from another piano tuner:

Hi there Brian. I'm a piano tuner working in Newcastle, NSW (Aus). I've just taken possession of a very poorly treated Kawai CE7N with heavy corrosion on the bass strings, multiple broken treble strings as well as numerous problems with mouse activity in the action and ingestion of the undersides of the keys!

I'm particularly saying a big thank you for your posting of your method of cleaning the bass strings, as well as the photographic evidence of the outcome.

I have removed the bass strings (and strung them through a broken wire) but hadn't thought to hose down the strings with water. I really was encouraged by your photos, though, as the corrosion that you had to deal with was significantly worse than that on my piano.

Again, many thanks for the description of the service, and all the best for your ongoing business ventures!

Kind regards,
Ian Brown

June 11 2017

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