What's the problem with Used Yamaha Pianos made for the Japanese market?
Yamaha has been making pianos for over 100 years. They had been manufacturing them for Japan and the Asian market for over 50 years before exporting pianos to North America, Europe and Australia. In the 1960's, Yamaha began exporting pianos to these new regions. Yamaha engineers were not aware of the level of dryness that existed in North American homes. Consequently, some of the Yamaha pianos sold in North America during the 1960's developed dryness - related problems. Upon researching these problems, our engineers found that in general, the indoor environments of homes in North America are considerably drier than in Japan.
This research led Yamaha to the development of computer-controlled drying kilns, as well as other manufacturing procedures, so that pianos destined for dry climates would be properly seasoned for the homes they would be placed in.
The used pianos being brought to North America today are pianos that were manufactured for the Japanese market. These instruments were manufactured using the same seasoning techniques that were used on the many pianos we had moisture-related problems with. To make matters worse, these pianos have lived in a very moist environment since they were new.

So what does Yamaha Corporation Of America recommend?*
Will one of these pianos develop severe problems after drying out in your home? Unless the piano is placed in a very humid environment (similar to Japan), the piano will dry out, and may develop problems that will be expensive to correct. We know this from the numerous calls we receive from customers and piano technicians reporting dryness-related problems with these used pianos brought in from Japan. We do not experience these types of problems with pianos that are seasoned for the North American market.
Based on our experience with pianos not seasoned for the North American market, from a service standpoint, we strongly discourage the purchase of one of these "made for Japan" pianos.

Bill Brandon
Yamaha Piano Service Manager, Yamaha Corporation of America

*The above comments while written for the US market, clearly apply equally for the Australian Piano Market. They give the historical reason behind Yamaha seasoning pianos specifically for different climates. It was not just an idea of a good thing to do, it was specifically to overcome problems they were having because of dryness. This is why Yamaha is adamant that they need to go to the trouble of seasoning all timber to the correct moisture content for every piano they build, and are equally adamant that these pianos should not then be exported to a country like Australia with a different climate than the one the pianos were manufactured for.

WATER and WOOD
Extract from a technical discussion concerning the effect of humidity fluctuations on the piano - by Leroy Edwards - Piano Technician USA

A fundamental point, often misunderstood or ignored when working with wood, is that the physical size of a piece of wood is affected by it's moisture content. Not only affected, but greatly affected. This is what causes furniture drawers to stick or rattle and soundboards to crack or lose tone. The facts and figures that follow are taken from the book "The behaviour of Wood" by R.Bruce Hoadly.

A tree contains water, a lot of water. Once it is felled, it starts losing moisture to the air. The amount it loses depends on the amount of moisture in the air. Nature's goal is to have the moisture content of the log and the air become "equal".

The water in the log is stored in 2 different ways. One is the water in the cells and fibre construction itself. This is called "Bound Water". The other is the water in the cavities between the fibre constructions and is called " Free Water". A good comparison would be a sponge. When completely wet it has free water that you can squeeze out, and after the best job of squeezing has been done, all the free water is gone. What remains keeping the sponge wet is bound water.

In most freshly cut logs, water will account for 70 - 80% of their weight. In the drying process, losing all the free water (which happens first) will reduce the water weight to approximately 28%, regardless of the type of wood. Losing free water does not affect the dimension of the wood. If a piece of wood at it's fibre saturation point (around 28%) is placed into an oven, virtually all of the bound water can be removed, and during the oven drying process, the shrinkage of wood occurs in three different ways. It shrinks less than 1% along it's length, about 4% across the grain, and 8% with the grain.

When wood is seasoned to some specific EMC (Equilibrium Moisture Content) and the parts of a desk, table, piano or whatever are cut to specific sizes, they remain at those specific sizes only as long as the EMC of the wood does not change.

All furniture and piano makers have found that the environment in North America and Australia creates a situation that necessitates seasoning of wood to around 7% or problems will occur. In fact the extremes of low relative humidity in some homes in Australia can dry the wood below the 7% figure. 7% EMC is a point around which the EMC in homes in North America and Australia centres. Some days the wood will absorb moisture and the EMC raise above 7%, somedays the opposite happens. Wood has an elasticity function that allows some movement without cracking, but if the limit is exceeded, damage occurs.

We need to be aware that the hundreds of moving parts in a piano action are machined to very exact sizes, (particularly when compared to a drawer in a Chest of Drawers), and even small changes in sizes can cause problems. Other parts of the piano, such as the sound board and pin block can also be affected to varying degree.

SEASONING REDUCES THE MOISTURE CONTENT OF WOOD
Yamaha seasons timber for piano manufacture, depending on the relative moisture content in the major cities in the country in which they will be sold. For Asia to 11% EMC.For Europe 9% EMC. For North America and Australia 7%.
3.5% CHANGE IN EMC CREATES A 1% PHYSICAL SIZE CHANGE
DAMAGE CAN OCCUR TO A PIANO BECAUSE OF LOWERING EMC AFTER CONSTRUCTION
If the soundboard becomes smaller, a small amount of shrinkage means the curvature becomes less (some crown is lost) which causes loss of tone quality. More shrinkage means greater loss of tone quality. Still more shrinkage can cause cracks in the soundboard, and buzzes and vibrations in the sound.
As wood in the action shrinks, the excellence in the touch that Yamaha is renowned for is lost. The keys don't stop working, but a prime reason for buying a Yamaha piano is their exceptional "action" or "feel" and this will be lost.
As wood in the pin block shrinks, the pins can become loose, and therefore the piano will go out of tune.
As wood in the body shrinks, glue joints become stressed and can finally fail. Cracks may appear in the basic construction of the piano - back posts, curved rim, etc. Some back posts may no longer touch the rim. Polyester finish may crack or lose adhesion to wood surfaces.
Relative Humidity (RH) is the percentage of water in the air compared to the maximum it could hold at that temperature. Reports on TV or newspapers quote outside RH not inside.
To keep wood at 11% EMC it is necessary to keep the room at a constant 60% RH.
To keep wood at 7% EMC it is necessary to keep the room at a constant 35% RH
4% EMC change = 1.14% shrinkage in size of wood
This means that every piece of wood in a second hand imported Japanese piano will shrink or be under stress to shrink just over 1% just to meet USA/Australian standard.
Wood parts that can shrink include soundboard, action parts, cabinet parts, tuning pin block and any part not glued to another part. Wood that is under stress and trying to shrink includes parts that are glued together like laminated wood. Even parts that are glued together will shrink an amount and can finally break the glue joint.

FIGURES TO REMEMBER
60% Relative Humidity (RH) produces 11% EMC. 35% RH produces 7% EMC.
25% RH change produces 4% EMC change.
4% EMC change produces 1.14% size change.

Yamaha go to enormous trouble to season their pianos for different climates. They need to ensure that all the timber required to produce the piano is ready at the same time, and then they produce pianos for a particular climate. This means that orders need to be placed months in advance from each country. After manufacture, the pianos are kept for 14 days in a humidity controlled area in the factory to stabilise. Then they are sealed in a moisture proof bag inside their box, and shipped out. You can imagine all the extra work, planning and therefore expense this causes. Yamaha would not do this unless they knew it was important.
It is quite humorous that people selling second hand imported Yamaha pianos actually will tell you to buy Yamaha because they are the best pianos, and have the best action, and the best tuning stability, the best sound etc, etc. This is clearly because Yamaha have done such extensive research and use such precise manufacturing processes. Then they will say to you "Oh, by the way, don't bother about this made for Australia business - Yamaha don't know what they are talking about" What a joke! Yamaha do know what they are talking about, that's why they make the best pianos! You can't have it both ways!

Yamaha are the experts on Yamaha pianos, and they are warning you not to buy a second hand imported Yamaha. Don't be misled!

Who's the expert on Yamaha pianos?
Yamaha is.

YOU CAN PURCHASE A NEW JAPANESE YAMAHA PIANO FROM UNDER $6500