What is Piano String?

Piano string or some may refer it as piano wire, is the wire used for the internal strings of a piano. Piano strings are commonly made of metals and alloys such as aluminum, brass, copper, or stainless steel. The thickness of piano wire can range from 24 gauge, or 0.022 inches (0.5mm), to 6 gauge, or 0.192 inches (4.8mm).

Replacing a piano wire is not a difficult task, but for a layperson it can be a dangerous task. It is recommended that one hire a professional if your piano needs some work. On virtually all pianos, replacement involves loosening the two tuning pins which hold the length of wire in place — this is done by turning the pins approximately four full turns each, alternating between them. Once loosened, the length of wire is loosened from the pin, and removed entirely. This may require some cutting, depending on how securely the piano wire is attached. The removed wire is then measured against the new length of wire (adding some length for any that was broken off during removal), and cut. The new wire is then connected by tying it to the tuning pins, which are then turned four full turns to clamp the new wire in place. The final task is making sure the string is properly tuned, which is done by trial and error and turning the pins ever-so-slightly. Properly tuning a piano can be a difficult task, and is usually best achieved with the help of a professional.

Strings and Things (in case you were wondering….

Although there are only 88 keys, the average modern piano has over 230 strings, one string per note in the low bass, two strings per note in the upper bass, and three strings per note in the treble. Pianos made in the eighteenth century were not as powerful and used low-tension wire made from an alloy different from the wire used today.

Tension averages approximately 160 lbs. per string. All together, the strings are stretched to a tension of 18 to 20 tons. A concert grand piano may have a combined string tension of up to 30 tons.

The strings gradually increase in thickness and length from treble to bass, and bass strings are wrapped with copper to make them produce a lower pitch.

Pianos range in weight from about 300 lbs, for a spinet to almost 1000 lbs. for a concert grand.

There are 8000-10,000 moving parts in a piano.

Piano Bass Strings

Bass String

If the bass strings were made of plain steel wire, the lowest notes would have a string length of around 25 feet long! Since the piano has to be able to fit into normal-sized living rooms, the designers had to achieve a lower pitch using shorter wires. Getting a lower pitch with shorter wire requires using a larger diameter wire. Unfortunately, if a wire is used that has too large of a diameter, the wire will break under the required tension. The solution is to use a smaller steel core wire and then to use another wire wrapped around the core wire to add mass. The extra mass makes the wire behave as though it is a larger diameter wire without causing the problems of string breakage.

Originally, the wire that was used to wrap around the core wire was made of iron. Later, some pianos were made with aluminum-wrapped bass strings, and now copper wrapping is used. Plain steel music wire is used throughout the tenor and treble sections of the piano.

Steel String

A common question is “Why does the piano have only one or two wires for each note in the bass section and three wires in the rest of the piano?” The short answer is that the number of wires used for each note helps determine the volume of that note. A large bass string can produce much more volume than a smaller plain wire. The volume is balanced by using more wires for each note in the treble section and fewer wires for each note in the bass section.

Why Piano Strings Break!

Imagine the sound of a whip snapping against an aluminum pie pan and you have some idea of the sound that occurs when a piano string breaks. It’s startling for anyone standing nearby, but especially so if you’re seated at the keyboard!

Realize that the thin steel string are tensioned to an average of 150 pounds each and it’s not hard to understand that they might break occasionally. Though they’re engineered to withstand the high tension, three main factors can cause them to fail.

Corrosion
Over time, especially in a damp environment, piano strings can rust. The rust eats into the steel wire, causing weak spots which can then break during the stress of hard playing or simply during routine tuning. Replacement is the only cure for rusty strings.

Excessively hard playing
Bend any piece of metal far enough and often enough and it will break. That’s exactly what happens to piano strings. Sustained hard playing, especially the rhythmic left hand style used in many churches, can drive the piano’s hammers against the strings with such force that they eventually break. Regular maintenance to the hammers can reduce breakage, but very hard playing will still take its toll. One solution is to amplify the piano with a microphone and sound system so it can be played lighter and still produce adequate power.

Very hard and worn hammers
With use, the smooth rounded surface of a piano hammer wears flat. Instead of striking the strings with the flexible, rounded shape of a rubber ball, it smacks them with a flat, hard surface. This can over-stress the strings, especially if the hammers are also made of very hard felt. In this case it is critical that your piano technician keep your hammers properly shaped and their hardness adjusted through a process called voicing.

Broken Piano Strings

Occasionally a wire will be broken and need to be replaced. If the string is not replaced promptly, it can cause uneven wear on the hammer that will lead to additional repairs being necessary. A string can break for a number of reasons. In most cases of string breakage, there usually is the presence of rust that weakens the string. The string might break because of a kink or a bend in the wire, or there may be a defect in the wire. In tropical areas or areas with high humidity, pianos are made using tinned wire to prevent excess rust. Strings frequently become brittle with age, and the splintered ends of a broken wire can testify to that. Concert instruments and other pianos that receive a lot of heavy use are notorious for popping strings.

When a piano is being tuned and a string breaks, it is usually due to a weakness in the string as listed above. Sometimes the wire can also be broken by a piano tuner who does not use a proper technique in using the tuning lever. When the broken wire is examined and the wire shows evidence of “necking down” (the wire being overstretched to the point that the wire is damaged) it often is the fault of the tuner. If a piano is flat in pitch because it has been neglected, the pitch raise can cause rusty strings to break. However, I have successfully raised pitch on a number of old pianos that had very rusty strings and were more than a whole note flat in pitch, and often the entire tuning will proceed without any of the strings breaking. Other times I may be tuning a much newer piano that is not flat, and a string will just decide to break.

Piano String Replacement

Is to replace a broken wire with a new wire. Piano wire comes in long coils that are several hundred feet long. I use a micrometer to choose the appropriate gauge of wire, cut off the appropriate length, and do the replacement. When a bass string breaks, you have the option of having the string replaced with a universal bass string or a custom-made bass string.

A universal bass string set has a number of different sizes of core wires with different sizes of copper wrapping. The replacement is cut to the correct length, and then the wrap wire is “unraveled” until the beginning and end of the wrapping matches the other bass strings on the piano. The problem with using universal bass strings is that often the tone of the new piano string is decidedly different from the surrounding strings. It is rare to find a universal bass string that will perfectly match the core diameter and wrap diameter of the broken wire. Also, I have personally had a problem with universal bass strings breaking shortly after they are installed.

A string maker will make a custom bass string precisely to the correct size. The string maker already has a list of stringing scales for many current production pianos, but an older or obscure brand of piano may not be in their files. To find the correct size of wire requires either sending the broken string to the string maker, making a paper pattern, or taking several measurements of the broken string. Custom-made bass strings involve more work, take more time, and are more expensive, but it is my preference to use them, because they give the advantage of matching the tone of the existing strings much more closely.

Piano String Repairs

When a piano string breaks, there are several repair options available. A broken string can be repaired by tying a tuner’s knot to splice the old wire to a short piece of new wire. The advantage of such a repair is that an older wire that is spliced will often match the tone of the surrounding strings better than if it had been replaced. In addition, a string that has been repaired this way will stabilize much more quickly than a new wire. Tying a broken string eliminates the need to return several times to retune the string back to the correct pitch. The drawback is that a wire with a knot in it doesn’t match the other wires in appearance.

Piano Restringing

An older piano often will develop a lot of rust on the strings, or it may have a problem with breaking strings. The bass strings often become tubby and “dead” because dirt and debris will be caught in the coils and make the strings not as flexible. The bass strings can sometimes be rejuvenated by working to get the junk out of the coils, but it is preferable to replace the entire set.

When restringing a piano, the tuning pins and strings are usually replaced as a unit at the same time. When the strings are removed, they are carefully measured and the scale design is calculated to determine what size of strings should be used for replacement. Good quality newer pianos often will have an acceptable scale design, but old or obscure piano designs can often be improved upon, especially in the bass section. The tone of the piano can often be improved by “tweaking” the scale design.

Although piano wire is made of steel, it does have some elasticity and does stretch. A new piano, or one that has been restrung, will continue to stretch and go flat for quite some time. If you have ever replaced a set of strings on your guitar, you know what I am talking about! After a piano has been restrung and returned to the customer’s house, it needs to be tuned a minimum of four times that first year and a minimum of twice a year thereafter. It is my opinion that a piano will stabilize much more quickly the more frequently it is tuned.