Here are some details of of the Henri Rudert that I took in recently. It really is the most lavishly decorated guitar; the workmanship is some of the finest I have seen. Like many guitars, it has suffered damage over the years, most of it due to humidity changes. The main area of restoration on this instrument is focused on the back, which has split from end to end. (see here)
The back is constructed like many guitars from the 19th century; spruce veneered with a decorative hardwood, in this case flamed maple. This type of construction allowed for a more economical use of precious and beautiful woods but over time the tensions in the back have caused it to split. Not only has it split; it has also curled up on either side of the split, as can be seen in the picture above.
I removed the back without using heat or water as the old glue was pretty degraded and came apart quite easily. I was pleased not to be using water as the delicate banding around the edge of the ribs is very delicate. Once the back was off the one remaining attached bar was removed, as was the label. The label was in two halves as the back had split through the middle of it. The back was then completely separated and ready for careful rejoining.
The curl in the back was removed by gently heating, followed by prolonged clamping. The split had at some point in the past been filled by a crude mastic, or filler and this had to be painstakingly picked away by hand. Very often the most time consuming part of restoration work is correcting or reversing previous repair work and removing this hard filler was a slow job that I completed over a number of days. Once the old filler had been removed I had to decide how far to go in rejoining the back. Ideally I would get a perfect match but the distortion of the wood over time prevented this. Also, the split is not straight edged, but is tightly waved, following the flame of the maple.
And finally, the picture below, shows the signature and date found pencilled on the inside of the guitar when the back was removed. I am used to seeing these and other marks in old guitars, but I was very pleased to fine this one, especially as it gave a precise date. It also captured a brief moment in time, when a guitar maker, busy in his workshop, signed and dated his work, just as I do now.