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Is there a way to test original wire to help choose correct replacement wire?

I have two Chickerings on my plate. A 109-C, 1896, and a scale 19, 1867. The 109 is underway, the 19 is in the contemplation phase.

Not too long ago, we had two choices in wire. More sililar to each other than different. Mapes or Roslau. The question of proriety was minor, as there was no real choice. Today there are more options, like Paullelo. But options mean choice, and choice requires information if it is not to be a blind choice.

I have the original wire from the 109. Does anyone know of a test to determine the best match in new wire?

You can try to determine the young's modulus of original wire, but as it is old the numbers will be higher.

Despite that you can see that some wire was softer. (others where also harder than today, possibly around 1900 (higher carbon content)

That should be interesting to compare old Roslau
And recent one. May be that could help to determine at large the original modulus of old type wires.

I have had good experience with Paullelo strings, and he is very helpful with information about which strings to use.

Tensile Strength test.

There was tremendous competition in the 1800's for the strongest wire.

Interestingly, the stronger the wire, the stiffer.

Regardless of wire though, resulting tension will be related to mass, string length and pitch. If you leave the wire sized unchanged, the piano will be under the same stress or tension.

The character of sound will be related to the stiffness of the wire.

Feel the wire in your hands.
Test the tensile strength by loading it until it breaks. Choose a wire of similar strength.
There may be a simple scientific method for measuring stiffness, I have to profess ignorance here.

you rub the string with a rosin impregnated cloth and measure the pitch of the longitudinal wave obtained.

Have to be compared with a formula using wire jauge and lenght.

I guess result approximate at 10%

Very convenient have a method with strings under tension

http://www.lulu.com/shop/jean-louchet/le-guide-du-cordage/paperback/product-16066859.html (use Amazon the delivery is better)

Would the long term tension on 90-110 year old piano wire affect its stiffness?
I would think so.
Would that same factor affect its tensile strength?
One would assume so, since they are more likely to break.

It seems to me, due to these factors, that any evaluation of the old wire, as a means to choose the new wire, would be difficult and likely deceptive.

I share an interest in the subject due to a small grand which I am doing soon. From what I understand, the choice of wire type will be very important to getting a clean sound. It may even be that a deliberate choice to lower tension via lower gauges with a softer wire will be part of my answer for this piano.

The basic analysis today is to look at the breakin strain % with the actual scale.

You can find high tension ld scales (with lo iH ) and low tension scale s(as Bechsteins ) high iH

To use soft wire you have to stay on low BS% then it raise from note 49 60% minored BS to the top at 80%

But I know at last one major modern brand that use high BS% yet in the mediums, and I find similar data on 1915 French piano (very even progression, but very high solicitation)

That plays a role in the mechanical behavior of the wire, better flow of tone, an important parameter, but the numbers we use in Europe are computed after a lowering of 20 25% of the breakin strain limit of the wire (a security taking in account the bends and the coils)

So it is difficult to compare numbers on both sides of the pond..

Likely there is some change. I would not let that deter me from investigating how the original wire behaves.

Chickering, for a time, recorded one page per piano notes on many details, including the brand of wire they used.

You can likely get a copy of the page from the log book from the Smithsonian American History Museum in DC.

Your piano may or may not have the extended details, it is worth a call to see.

Details of how music wire was made and it's tensile strengths are well recorded in the 1800's.

The MFA in Boston has a very good Chickering collection. Darcey Kironin, Curator, would be the person to contact. He has very good resources there.

The English version of the book Olek mentioned:

http://www.lulu.com/shop/jean-louchet/the-keyboard-stringing-guide/paperback/product-6472282.html

I will give you the formula, which is quite simple.

My idea was that may be the stiffening due to age could be evaluated.

Precision is out of question, and, for instance we are not even sure of the original pitch of the instrument - pitch change the sollicitation of the wire, hence change the BS% and change the iH a little.

I am deeply intrigued. I like the notion of getting the wire to speak for itself. I am ordering that book tomorrow.

Larry,
thanks for responding.

We have touched on this before. Does not an increase in the strength of a wire come with an increase in the density of the wire, and a greater mass per unit of length? Would this not require an increase in tension to reach pitch?

I have to ask because I do not know.

What is sollicitation?

What sort of results do you want? Do you want the best possible piano it could be, or something close to what you think it might have been like when it was new?

Originality. The customer is interested in experiencing the piano the way it was when new. Chickering sold thousands of these pianos for very good money. He wants to hear what it was that kept Chickering flourishing for so many years. Perhapse that is the best possible piano, or at least the best possible 100 year old Chickering.

A crime in most places!

I knew I was going to play somebody's straight-man asking that question.

Craig,

I could NOT resist!

We did a 1881 Chickering scale 93 thirty years ago and dropped most of the gauges back .002" and added half sizes. The plate was massive, but the sound board assembly was dainty. I wondered if the piano ever could have had real down bearing. It was as if they were going on the premises that maximum string mass was the answer to all things and if you could build a plate to hold the tension, all was well.

Weird job. The first rebuilder had passed away and I took on at least three contracts to finish up. This one and, I think, two upright players.

From my notes which I have just looked over, that steel was STRONG stuff. Smallest size was 14!

Oh, yeah,
Chickering was not kidding around. I'm not planning on changing the string scale. That is why I'm trying to determin the proper stiffnesss of wire to install. If the stiffness affeccts the tone, as Larry said, then I don't want to use a wire any stiffer than what is right.

The board does seem to be a bit more compliant than a Steinway. And from what I could tell from teardown measurements, Chickering employed a one to one ratio between crown and bearing in this 109. Once again, no messing around. though I would think a high compliance board could handle that type of bearing without choking.

Did you find that in yours? The 1867 scale 19 has a board that looks like a guitar bottom. Thin little triangular ribs spaced about 10 inches apart. I've never seen anything like it, and I cant wait to recrown it and hear what it sounded like.

Paulello has a typogram, available to download for free, which can help you determine what wire to use. You will have to measure the existing scale and input the data to the typogram. Here: http://stephenpaulello.com/en/typogramme