Grand Piano Restoration: Sounding Board Finish & Plate Gilding.

Instruments located and used in an education facility tend to get quite dirty; it is impossible for the laymen that use the equipment to have the proper tools for cleaning underneath the strings. The result is that the sounding board area underneath the strings has several layers of dust. Dust and dirt attract and hold moisture, which in turn causes deterioration of the finished surface of the sounding board.

The iron plate must be lifted out for cleaning and refinishing of the sounding board, along with replacement of the sounding board decal. 

Often times the colour of the sounding board has deteriorated and the wood looks somewhat lifeless. To brighten up the look and make the wood look like new, one has to have knowledge of the colour spectrum, and which colour stains to add to the clear coat lacquer.

Once the finish on the sounding board is complete I place the plate directly over top of where it locates inside the casework. This way I can gild the plate with gold powder, and then drop the plate right into position.

The gilding powder comes from Belgium, and is mixed in with clear lacquer to create the metallic flake gold finish. Modern equipment allows us now to shoot the gold powder through a spray gun eliminating the need to apply the gilding powder in the old way. I use the gilding powder and create my own mix rather than purchase the aerosol cans already mixed up. This allows me to add colour tint to the mix so that I am able to match the original gilding colour, as the gold colour is varied at times. 

Of course there are possible sounding board repairs at times, which must be completed previous to doing any finishing. With the sounding board on the Heintzman there are no repairs and the board shows measurable crown and downbearing.

 Also there is the prep to the iron plate; cleaning sanding and filling any chips or gaps.

Below at the link provided are series of photos on how I do the sounding board refinish and the plate re-gilding.

Same photo set starting at photo 77.

Sound Baord Finish and Plate Gilding

Grand Piano Restoration: Action & Keyboard

Remember to take some of the general measurements of the action and keyboard. Most important are the original measurements within the action and keyboard geometry and the tolerances for how it plays at the moment with all of the worn parts; not too important to be concerned about the string line as the plate will be raised for re-gilding. 

Because this action has a partial hammer set replacement there will be difficulty in obtaining original geometry for the extreme treble areas. 

Lots of the common repairs required here; all keyboard under felts, a full set of key bushings top and bottom, back check leather replacements, whippen heel, drop screw and let-off replacements, along with hammer shanks, flanges and hammers. 

Now that the entire instrument has been dismantled, there are several stations to work at, the action and keyboard restoration, the cabinet and woodworking, then the fixed structure of the instrument, the plate, sounding board, bridges and pin block. This prevents a work stoppage in case of machinery breakdown or lack of proper parts; one can switch to another area to continue working.

Same photo set starting at photo 63.

Action and Keyboard

Grand Piano Restoration; Understring Felt and Bearing Bars

Following string removal in years past, time would be spent marking, measuring, and recording the distances between the bearing bars and the hitch pins. As the plate is being re-gilded, all of the existing marks and measurements for bearing bar placement, strings sizes, manufacturer decals, and any other plate markings will disappear.

These days I use a digital camera to record a photograph of each bearing bar and its distances from the corresponding hitch pins. Then following gilding, the bars are replaced in the exact position as previous.

The under string felt is removed and stored for matching up to new cloths at a later date previous to stringing.

Same photo set starting at photo 55

Understring Felt and Bearing Bars

Grand Piano Restoration: Letting the Plate Down

Most of the instruments that come to the shop for restorative work have been up to pitch for a long period of time. The entire piano framework has been under tremendous strain for many years; decades in fact.

When letting the tension off the plate, this must be done safely as the sudden release of pressure could cause an unbalance of the plate or other structural components of the instrument. Very much like unbolting a car tire the weight or pressure must come off evenly distributed. With almost 20 tons of pressure on the framework one cannot tell if major structural components have deteriorated to the point of collapse and are being held in place only by the tension applied.

Over the years I have used this procedure successfully time and time again. It is the safest way I have found to let down the tension from the piano.  This task is best completed using a 4ths and 5ths temperament.

First take middle C and tune down so that middle C becomes the same as the B below. Then tuning in octaves tune all of the C’s to that pitch or tune all of the C’s to the B below. The result is that middle C is now a full tone lower than originally.

Next tune the F below Middle C to the E below F. Then follow the same procedure used for C.  Next, tune all of the F’s by octaves or tune the F’s to the E below. After F, then the G below middle C down to beat less, then the D above middle C down to beat less, then A below and so on. Work your way around the temperament until you have completed the temperament.  Each time you lower a key in pitch do all of the same keys of the keyboard. It is not important to fine tune as you go. Just rough in the keys and make them close to the pitch you are looking for. 

The end result will be that the entire piano will now be a full tone lower that A440 which means that you have released approximately 4 tons of weight off the iron frame.

Now return to middle C and begin again by lowering the pitch to the B below. Work your way around the temperament using this new pitch. At completion of this second step the piano will now be two full tones lower than A440. 

From here you can take a T-handle or a stringing hammer and turn the tuning pins one half turn so the remaining tension is released.  This process once learned can be completed in about an hour.

Some photos of the process; please begin at photo # 47

Piano String Removal

Grand Piano Restoration: Dismantle, Label, and Store

The piano will be apart for a period of time. It will be impossible to remember the way things came apart exactly and this is why it is so important to take a lot of notes, and label things as to where they are located and how they came apart.

Take notes or photographs of all procedures.

The piano arrived in the usual way; brought into the shop and set up on its legs by the movers. I place my grand’s on a shop truck that was built out of heavy timber. This sets them up high off the floor so I can work on the insides without bending over all day long.

Here are some early photos of the cabinet dismantle. Please start at photo number 35.

Dismantle Label and Store