Pianotech

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there. 

I've addressed this multiple times in the various classes I do that include discussions about soundboard design and structure. I've probably also written about it but I'm not going to try to find the references.

I have not been able to find any early theoretical basis for the practice. It seems to have just appeared on the scene as an accepted fact-we see some soundboards with crown, they work, therefore all soundboards need crown.

Prior to the 1920s the only adhesives available for joining wood-to-wood surfaces were made from constituents of animal hides, hooves and bones. These glues had to be applied hot. If they were applied to a cold substrate they started to cool rapidly and gel-weakening the bond. Hence the practice of heating the substrate was developed. With limited production this could be done individually: a panel could be stuck in the hotbox for a little while until it was hot enough, removed and ribs glued in place. Done carefully the soundboard panel might not be in the hotbox long enough to have changed dimension appreciably. There might or might not be any residual crown in the system.

But as production demands increased the practice of maintaining a stock of pre-heated panels came into common use. These panels might spend anywhere from hours to days in the hotbox prior to being ribbed. They would shrink to some stable point depending on the temperature and relative humidity in the hotbox. Now when the ribs were glued on and the assembly returned to whatever "normal" atmosphere might be, the panel would expand-or try to-and a stress interface would build up between the surface of the ribs and the soundboard panel causing it to warp. "Warp" is not a good marketing term, of course, so a new term had to be invented and that word was "crown."

Different manufacturers seemed to each have their own standard-if there were any standards at all. The earliest written record I have found of this practice (in English, at least) is Wolfenden's: "... arch the bars in the usual curvature, keep the board warm at, say, 100° to 120° F, for a few hours to shrink it. Place it on a frame or board hollowed out a trace deeper than the curve of the bars, and while the board is hot glue the bars down." Not a very precise process but there sure as hell was going to be some "curvature" in there.