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Why polish only one side?


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Hello all, coming from a furniture making background, it has always surprised me that the concertinas I have had have only been finished on one side. The inside never appears to be sealed. This leads to uneven moisture absorption and consequently twisting. the cheaper instruments would not have been made with quarter sawn timber so the effect would have been even worse. I'm interested to know whether modern makers (there are a few here) would agree with sealing both sides of the wood and, in the case of veneering, whether they would use a balancing veneer on the reverse side.

Andy.

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Andy,

Most musical instruments are only finished on the exterior. I would venture that convention came about to allow the inside to absorb and reflect sound in a way that a finished interior does not.

 

Baffling can have a marked effect on what overtones are reflected and absorbed. Open and closed (total area) also effects quality and volume of sound.

 

I have worked on one Aeola that had a partially finished interior (around the button area). The sampling is too small to speculate but I did note it had very even and clear chords.

 

Most concertinas after 1880 are made with 3 ply ends. The notable exception being the 20b mahogany Lachenals.

 

Greg

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That's very interesting Greg. I must say I hadn't considered the acoustic effects. I can see that a sealed timber would reflect more than an unsealed surface. I'm also intrigued as to why the longitudinal reed frames didn't eventually split the timber along the grain. Some of them are very tight into the slots.

Andy.

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That's very interesting Greg. I must say I hadn't considered the acoustic effects. I can see that a sealed timber would reflect more than an unsealed surface. I'm also intrigued as to why the longitudinal reed frames didn't eventually split the timber along the grain. Some of them are very tight into the slots.

Andy.

Sorry double post oops!

Edited by Andy Holder
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Andy,

it appears to me that,whilst most of the modern furniture in my house is coated (finnished) all over, the older pieces tend not to be. I'm thinking particularly of Table tops which it was allways my impression were varnished, lacquered,waxed etc., whilst the under sides were left un-finnished. I assume that the older pieces were made from well seasoned,air dried, timber and that the bare wood surfaces would allow moisture to come and go naturally with changes in humidity whereas modern 'Kiln dried' timbers would be worked quite quickly after the drying process and then sealed to maintain a specific relative humidity. But I am not a furniture maker so perhaps there is another explaination.

 

I would agree with the point that Greg makes regarding the general rule that musical instruments are only finnished on the outside because a piece of wood which is coated all over does not react in the same way. The reflection of sound waves and their absorbtion at the wood surface will modify the tone and create the quality of sound that that specific wood has been chosen to enable.

 

I choose very particular types of wood for my instruments, for their accoustic properties, and whilst I could decide to coat them all over for the sake of stability I feel this would detract too much from the original intention of their use.

 

Improved stability was the probable reason for the later use of Plywood in the production of concertinas (both for the 'ends' and quite a bit later the reedpans too) but more likely this was due to not having to 'stock' solid wood for many years whilst it stabilised. I recall a conversation with Harry Crabb where he talked about the thick planks of Sycamore that were very gradually planed down, one pass through the planner each year for 25 or more years, untill they reached the required thickness and stability for concertina making.

 

It has long been my opinion that the use of laminated wood for this purpose has to have an adverse effect on the instrument's tone. Each layer and its glue coating combined with the change of direction of the grain (with each layer) can dampen the harmonics of the notes. The original designers chose woods for their accoustic charateristics... that most reedpans have not split along the grain due to the wedging forces of the reed shoes is probably due to the slight squashiness of those reedframes and the super well seasoned wood utilised. The first notice of a swelling reedpan is when the reed tongues start to scrape at their frames and produce buzzing noises due to the wood getting larger and thus the slots for the reed frames get smaller. This can happen with both wood shrincage and swelling due to changes in Humidity.

Edited by Geoff Wooff
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Part of this relates to the quality of wood that is generally available. My father was in the sash & door business, plus custom millwork, late 40's through early 1980's. Much of the wood we bought and used was extremely good quality. Most of it was heartwood, the outer layer wood being considered as only good for strapping or pallets. In fact, a sailboat we built had mahagony decks made from the packing crates that window glass came in.

 

As time progressed, the manufacturing techniques had to adapt to a poorer quality of wood. It wasn't even a matter of choice, the high quality wood just plain wasn't available on the market. Designs also had to change to reflect the poorer properties of the wood.

 

This shows up quite vividly in the later manufacture Wheatstone's where we see ends made from what I know as "Phillipine mahogany" - the stuff that used to be made into packing crates. I just refinished the ends on "the cheapest of cheap" Lachenal (brass reeds, 4 fold, bone keys, 1920's) and in my opinion the quality of the mahogany used is miles better than this "Phillipine mahogany". In fact, it is almost as good as some "Santos rosewood" that I paid a steep price for.

 

So I suspect that it wasn't just the sound quality issue, the quality of timber made it an unnecessary expense to finish the back side. Lachenal's were certainly not prone to unnecessary expenses on their bottom end instruments. I'm pretty sure that if the cheapest way to build these low end concertinas involved finishing the reverse, then that's what we would see.

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Andy,

it appears to me that,whilst most of the modern furniture in my house is coated (finnished) all over, the older pieces tend not to be. I'm thinking particularly of Table tops which it was allways my impression were varnished, lacquered,waxed etc., whilst the under sides were left un-finnished. I assume that the older pieces were made from well seasoned,air dried, timber and that the bare wood surfaces would allow moisture to come and go naturally with changes in humidity whereas modern 'Kiln dried' timbers would be worked quite quickly after the drying process and then sealed to maintain a specific relative humidity. But I am not a furniture maker so perhaps there is another explaination.

 

I would agree with the point that Greg makes regarding the general rule that musical instruments are only finnished on the outside because a piece of wood which is coated all over does not react in the same way. The reflection of sound waves and their absorbtion at the wood surface will modify the tone and create the quality of sound that that specific wood has been chosen to enable.

 

I choose very particular types of wood for my instruments, for their accoustic properties, and whilst I could decide to coat them all over for the sake of stability I feel this would detract too much from the original intention of their use.

 

Improved stability was the probable reason for the later use of Plywood in the production of concertinas (both for the 'ends' and quite a bit later the reedpans too) but more likely this was due to not having to 'stock' solid wood for many years whilst it stabilised. I recall a conversation with Harry Crabb where he talked about the thick planks of Sycamore that were very gradually planed down, one pass through the planner each year for 25 or more years, untill they reached the required thickness and stability for concertina making.

 

It has long been my opinion that the use of laminated wood for this purpose has to have an adverse effect on the instrument's tone. Each layer and its glue coating combined with the change of direction of the grain (with each layer) can dampen the harmonics of the notes. The original designers chose woods for their accoustic charateristics... that most reedpans have not split along the grain due to the wedging forces of the reed shoes is probably due to the slight squashiness of those reedframes and the super well seasoned wood utilised. The first notice of a swelling reedpan is when the reed tongues start to scrape at their frames and produce buzzing noises due to the wood getting larger and thus the slots for the reed frames get smaller. This can happen with both wood shrincage and swelling due to changes in Humidity.

 

Geoff, that is a fascinating reply. I really didn't imagine that the timber would have so much effect on the sound quality as the ends aren't, strictly speaking, resonant, as they would be in an instrument with a soundboard. Also, you've got your hands all over it, damping any vibrations. However, I am pleased to learn from your experience, it's a long road and I'm only on the first few steps! The timber quality is certainly a huge issue. I believe a rule of thumb for general furniture making is air drying a year for every inch of thickness before it goes in the kiln. I can't imagine that happening these days. I recently bought some Iroko that was measured to be 10-12% and it sprang and twisted so much when cut that it was unusable.

One of the reasons for my initial post was that whenever I leave an end off for a while, it always cups the same way, i.e. up at the edges. This suggests that it is more to do with the one-sided finishing than any stresses left in the timber.

Thanks to you and many on this forum, I am learning this amazing subject at a fantastic rate of knots. Have a peaceful and musical Christmas.

Andy

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Part of this relates to the quality of wood that is generally available. My father was in the sash & door business, plus custom millwork, late 40's through early 1980's. Much of the wood we bought and used was extremely good quality. Most of it was heartwood, the outer layer wood being considered as only good for strapping or pallets. In fact, a sailboat we built had mahagony decks made from the packing crates that window glass came in.

 

As time progressed, the manufacturing techniques had to adapt to a poorer quality of wood. It wasn't even a matter of choice, the high quality wood just plain wasn't available on the market. Designs also had to change to reflect the poorer properties of the wood.

 

This shows up quite vividly in the later manufacture Wheatstone's where we see ends made from what I know as "Phillipine mahogany" - the stuff that used to be made into packing crates. I just refinished the ends on "the cheapest of cheap" Lachenal (brass reeds, 4 fold, bone keys, 1920's) and in my opinion the quality of the mahogany used is miles better than this "Phillipine mahogany". In fact, it is almost as good as some "Santos rosewood" that I paid a steep price for.

 

So I suspect that it wasn't just the sound quality issue, the quality of timber made it an unnecessary expense to finish the back side. Lachenal's were certainly not prone to unnecessary expenses on their bottom end instruments. I'm pretty sure that if the cheapest way to build these low end concertinas involved finishing the reverse, then that's what we would see.

 

Thanks for that. I too have noticed the degradation of timber over the last 40 years. I guess it's to do with profit margins and ever decreasing supplies. I used to do pattern making and the favourite for intricate designs was Jelutong. Nice 'n stable, soft grain, easily worked. We used to buy 2" boards that were 15" wide and 15' long, straight as a die. I never gave a second thought to environmental issues back then. What would you use in place of Rosewood now?

I don't know if it was an expense thing with the lower end instruments. What does it take to wipe on a bit of shellac (shellac was relatively much cheaper then than it is now). If only we could turn the clock back and have a look!

Seasons greetings to you.

Andy

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