So many ideas have been shared here...thanks.
Here's another, from Craig Hair and Richard Blais at Hampshire piano. They do piano conservation work. They tried numerous techniques and finally settled on a caul type technique that solved the problem that arises with cauls. The problem is that the radii of the cauls has to match the raidus not of the arm but of the arm plus the veneer(s). If not, the caul fit will not be an real cope and pattern, and there will be gaps in the pressing. I had this problem the first time I tried using a caul. So, here is their technique, which they shared privately, but okay'd me to share on the website:
"Hey Jim, gluing veneer on these curved surfaces was problematic, until a wooden cauld rough cut, "band saw" was pressed into place with layers of paper wet with water and a little glue to make it sticky.
The paper mache is layered to the thickness of the veneer and a little wider than the area.
When the paper mache is the proper thickness of the veneer to be pressed on it is important to include the paper thickness of the glue barrier that will be used when pressing on the veneer to be used.
In this case the "arms" then this wet sticky paper is laid in place of the veneer, the glue makes for it staying in place. The wooden cauld is buttered very thinly with bondo, then the cauld is clamped in place, on to the paper mache squishing the excess bondo out the sides.
When the bondo sets, and is not completely hardened, remove the clamp, the paper mache which was in place of the veneer will let go and can be discarded, leaving the perfect contoured surface, to match the veneer thickness when curved. And now is the time to trim excess plastic from sides of the cauld.
The veneer can now be pressed without gaps in the curvature, of course a paper between cauld and veneer.
The same thing has to be done on both sides, because they are never perfectly the same,----gaps usually occur, soooo. the same wooden cauld can be used for both sides. And the bondo can be removed with a heat gun or torch, about 180 deg, or so and it gets very soft to be able to remove it easily. "chizel"
Should you decide to go this route ----then I would be glad to help.
It makes for a good solid jointing, also we probably have vintage veneer here to match, there is no way in hell match this with newly acquired material, without a little color magicianship.
Be well!"
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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Original Message:
Sent: 11-14-2020 07:14
From: Peter Grey
Subject: Re-veneering front arm curves
Jim,
You are correct about the long grain piece not liking to bend well. This is likely why SS did not do it, as it would at least double the amount of time and labor needed for that job (they did of course crossband all their large flat pieces since these move A LOT with seasonal change). Likely they concluded that since their rim construction was super solid, the didn't need to worry about crossbanding, and it would easily last the 40 year design lifespan they intended.
Kevin Hancock Refinisher Extraordinaire in MD was the one who taught me about this. I have done it ever since. It just adds an extra layer (like a shock absorber) of insurance for that nice piece of mahogany or walnut or whatever that you're going to put on there.
Pwg
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Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
Original Message:
Sent: 11-13-2020 22:28
From: Peter Grey
Subject: Re-veneering front arm curves
With thin veneer it's not that hard. Crossbanding lends stability to the top veneer. The original was probably about 1/20" thick (or thicker). What you will be using is probably closer to 1/30" or thinner. I have sometimes used 1/40" mahogany as crossbanding. Very easy to bend once it's wet. Standard cabinetry protocol.
Pwg
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Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
Original Message:
Sent: 11-13-2020 21:02
From: Jim Ialeggio
Subject: Re-veneering front arm curves
I don't get the cross laminated part, because the 1st lamination will be long grain the length of the curve...and the veneer doesn't really like to bend tight radii along the grain. The top layer was grain perpendicular to the length of the arm, so I can see that bending well.
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 11-13-2020 18:43
From: Peter Grey
Subject: Re-veneering front arm curves
Piece of cake. Still recommend using crossbanding underneath. Today's veneers are much thinner than what they used back then. Do the vertical front face first, then overlap with the top curved one, then the top vertical overlapping that, first with cross banding (you can use the exact same stuff for that or poplar, just 90° to the decorative top piece), trim and repeat with the final veneer.
With hammer veneering you coat both sides of the veneer with glue, the top side lubricated the hammer action. It also makes the veneer flexible and keeps it from curling since you have same moisture on both sides.
Pwg
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Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
Original Message:
Sent: 11-13-2020 15:40
From: Susan Kline
Subject: Re-veneering front arm curves
Hi, Jim
I haven't replaced the entire veneer for a cheek, and my possible approach would probably require you to try the technique on some kind of dummy case part made of scrap, a few times.
Back when I was writing for the Journal (about 1977) my first article was about the effect which could be obtained by mixing white glue (or carpenters glue) with water thin CA glue.
For this job, the benefit would be very fast set up time, combined with what can often be quite a strong bond.
My own experience with this has been when the veneer was all there, but the glue had failed so it was loose till about half way up the arm. I took a fairly thin thickness gauge (from a set used to work on car valves), put some white glue on it, both sides, and ran it up between the veneer and the case, repeating till I had a reasonably even coat on the whole surfaces. Then, harder, having cleaned off the thickness gauge very carefully, I put dots of CA glue on one side of it, pulled the veneer slightly up, and slide the thickness gauge along the upper portion, near where the veneer was still glued down. Having removed the gauge, I pressed the part with the CA under it against the case till it set (a few seconds), then cleaned the thickness gauge again, added more, and gradually worked down to the front in a couple more stages.
The point being, for veneer which is still attached but loose, on a case part which cannot be clamped, once the two glues interact with each other, a strong reaction occurs. You can even feel the heat through the veneer as you press it. It's not too hard to press the veneer into the curve for long enough, using both hands.
Well, it might be of dubious merit as a technique for this particular problem, but it would have the advantage of being unlike anything else you could try. It does take very little time, and if the results are not good, carefully prying with a thin piece of metal (like the thickness gauge) will allow you to remove the part and try again, if done in the first few minutes after gluing it down. Removing the glues after taking the veneer back off might offer some difficulty.
Same thing with ivories -- if one goes on crooked (with the white glue on the keystick and the dots of CA on the back of the ivory), it is possible to take a thin knife and slide it back off. After 1/2 hour that would be harder to do, and the next day one would risk cracking the ivory.
Original Message:
Sent: 11/12/2020 3:07:00 PM
From: Jim Ialeggio
Subject: Re-veneering front arm curves
Anyone have any suggestions on re-veneering the curved front arms of a grand, you know, the part of the arms at the keyboard end, where the veneer is often damaged or completely missing. I have escaped having to do this with veneer, as most of my refinishing, has been black. With black, I just strip the damaged veneer and coat the arm with epoxy. Can't do that on a clear wood finish. I have tried clamping veneer previously with a custom curved caul, but the adhesion was not good. Its a hard nut to crack I think, otherwise this place would not be such a common site for veneer failure. Any suggestions appreciated.
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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