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Old Ivoroid
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=52232		 Page 1 of 1
Author:  Ruby50 [ Wed Jul 31, 2019 5:55 pm ]
Post subject:  Old Ivoroid
A friend had a friend mention that he had a piano with ivory keys my friend was welcome to take. My friend brought home a bunch and discovered that the keys are covered in what he said was "a plastic ivory with little straight lines in it". Well I went right over and got me dsome of it.

The first picture show some keys, and the second and third pictures show what a good match it is for ivoroid binding and sheet that I have - perfect match.

I soaked one of the keys in water overnight - about 14 hours, and the glue holding together some of the wooden parts together gave up, but the glue holding the ivoroid to the wood was holding tight. Then I boiled one for 5 minutes and the wood split apart but did not come off of the ivoroid. I scraped the wood off the back of the ivoroid with a sharp knife. The color lightened and the pieces were a little warped.

Does anyone have insight as to what glue this might be and how I can separate the ivoroid without damaging it? I have thought of cutting away most of it then using a router on the last bit - this would not change the color and would leave it flat.

The last picture is one of the wooden pieces cut in half showing how the grain runs side to side. It is lovely clear white pine. Why did they not cut the piece so the grain was vertical rather than horizontal? I have wondered a couple of times when cutting braces why the grain is better vertical than horizontal?

Ed
Author:  Chris Pile [ Wed Jul 31, 2019 6:45 pm ]
Post subject:  Re: Old Ivoroid
We need a piano expert...
Author:  Clay S. [ Wed Jul 31, 2019 9:49 pm ]
Post subject:  Re: Old Ivoroid
I'm certainly no expert, but I did take a course in piano repair many years ago.
Some of the old pianos used a white colored glue under the key tops that not only stuck the keys in place but also"brightened" the thin veneer of ivory or plastic glued on top. Soaking in a bucket of water for several days until the wood becomes totally saturated may allow the key tops to be removed more easily. Vinegar might work a little quicker.
As to the grain orientation of the wood, it provides the least change (from humidity fluctuations) in the height of the key which may help the action stay in adjustment.
The grain orientation for soundboard braces is not critical and lute braces were commonly oriented opposite what is conventional for guitars - and the same as you show for your piano keys. Strength wise there is not much difference, so it is more a matter of avoiding "runout".
Author:  B. Howard [ Thu Aug 01, 2019 5:47 am ]
Post subject:  Re: Old Ivoroid
That is most likely a casien based glue. Very waterproof.... Gibson used this same stuff on 30's archtops. Heat is the only way I know to release the stuff and it takes a fair bit. That would ruin the celluloid so I would cut or plane the wood away from the veneer.
Author:  Ruby50 [ Thu Aug 01, 2019 11:43 am ]
Post subject:  Re: Old Ivoroid
Thanks all. I have tried cutting close tot he line and planing on a little jig I made - will be successful, but the material is a little brittle so I have to be careful about breaking it while planing. Will work perfectly for inlays

Ed
Author:  guitarjtb [ Thu Aug 01, 2019 11:55 am ]
Post subject:  Re: Old Ivoroid
Ruby50 wrote:
Thanks all. I have tried cutting close tot he line and planing on a little jig I made - will be successful, but the material is a little brittle so I have to be careful about breaking it while planing. Will work perfectly for inlays

Ed

If you plan to use it for inlays, leave .010" to .020" of wood on the back side of the ivoroid and make the inlay pockets a little deeper. This will be easier and will help keep the brittle ivoroid from breaking. You should be able to cut that close on a band saw, and smooth enough that no other leveling should be needed.
Author:  Terence Kennedy [ Thu Aug 01, 2019 12:02 pm ]
Post subject:  Re: Old Ivoroid
I wonder if you couldn't plane the bulk of the wood and then double stick tape the keys to a carrier board and run them through the thickness sander.
Author:  Pat Foster [ Thu Aug 01, 2019 1:12 pm ]
Post subject:  Re: Old Ivoroid
Terence Kennedy wrote:
I wonder if you couldn't plane the bulk of the wood and then double stick tape the keys to a carrier board and run them through the thickness sander.


That's what I'd do, and I'm no piano expert!

With the grain running side to side, parallel rather than perpendicular to the surface of the keys, it might be that warpage might be in the vertical. If it were horizontal, there might be alignment issues side to side in that plane, which it looks like would be more difficult to correct.
Author:  Ruby50 [ Thu Aug 01, 2019 6:53 pm ]
Post subject:  Re: Old Ivoroid
The material is .06" cleaned up, same as the modern ivoroid I have, so there is enough thickness to play around with a bit. Sanding is the idea - you guys are great

Thanks

Ed
Author:  John Arnold [ Thu Aug 15, 2019 10:55 pm ]
Post subject:  Re: Old Ivoroid
I would be cautious when working with old celluloid, particularly if it is brittle. Camphor is added when celluoid is made; this stabilizes and plasticizes it. But camphor is volatile, and gasses out over time. Once this happens, it becomes an unstable material that can shrink, crack, crumble and in rare cases, spontaneously combust.
If it smells like vinegar rather than camphor when sanded or scraped, I would throw it out. The 'vinegar' smell is actually nitric acid fumes that are very corrosive.
Author:  Ruby50 [ Fri Aug 16, 2019 8:42 am ]
Post subject:  Re: Old Ivoroid
Thanks John - my material does not smell like vinegar. Although the idea of spontaneous combustion is oddly compelling.

Ed
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