Saturday, October 25, 2014

Eleven Course Lute after Magno Tieffenbrucker

I finished an eleven course lute using the bowl from Magno Tieffenbrucker's archlute C45 that is conserved in the KHM, Vienna. It is one of my favorite models and I have built it with various string dispositions; as an archlute, like the original, as a larger eight course and as a ten. This lute is strung in the old G tuning with an extended bass. The owner also intends to restring it for D minor. The string length is 646mm.

I built the mould for the lute around 1985 from plans drawn by Gerhard Söhne. It has given good service. I prefer working with solid moulds like this for lutes with many narrow ribs and open moulds for wider and fewer ribs. I have thirty odd lute moulds and they are split fairly evenly between the two types. My two posts from May 8 and 17, 2012 describe building a open mould.  This mould was assembled from blocks of basswood cut to specific cross-sectional profiles as denoted on the published plans, glued together (you can see the glue lines) and then sculpted to the finished shape.

The original archlute has a triple rose. When I build the archlute model I incorporate that design, but as a lute with fewer courses I use a single rose, positioned in the same location as the triple rose.

The design is a abbreviated version of a rose that appears on many renaissance lutes. My source is from the swan neck thirteen course by Joachim Tielke 1678, Bayerisches Nationalmuseum, Munich, Mu 10.

The bridge is constructed of plum with an ebony cap. I positioned it the same distance from the rear of the belly as it is on the original archlute. I think that maintaining Magno's original geometry for these features is as important as the shape of the bowl for preserving his tonal vision.

The original bowl is constructed with 31 ribs of yew with dark spacers. I used Indian rosewood with holly spacers.

The neck is constructed with a poplar core veneered with strips of black ebony that taper in width from the neck joint to the peg box separated by holly lines. I do not taper the strips individually. I carefully plane an ebony block to the required taper and cut each piece from its edge.

The finished pieces can then be lined up to check for discrepancies.

The length of an eleven course pegbox can be intimidating so I was careful in determining its proportions. The core is pear with an ebony back plate.

The cheeks are veneered with rosewood and holly. The chantrelle bracket is carved from a small block of ebony.

The ninth fret is tied on the neck but it sits very close to the neck joint which makes it very difficult to tie tightly. I like  to insert a tiny peg into the center rib to hold the fret securely in position.

I usually apply an oil finish to mult-rib rosewood bowls. But this time I decided to shellac it using a French polish technique.

 Solvents in the finish will often cause rosewood color to bleed onto lighter woods so I painted the holly spacers with several coats of shellac to seal them using a tiny brush. Then I filled the open grain of the rosewood with commercial wood filler. Once the filler was dry I scraped and sanded the ribs smooth.
 There are many descriptions of french polishing on the internet and if you are interested in trying the technique read a few explanations and watch the videos. Here I'll cover the major points of my technique but I think it is best if you develop your own through practice and patience. In essence, it is a simple procedure.

1. A 2 lb. cut of white shellac flakes dissolved in denatured alcohol.
2. 'Fads' or applicators made from good quality white cotton stuffed with cotton balls and secured with white cotton string.
3. The smaller fad is about the same size as the width of this lute's ribs and is used to apply the polish to one rib at a time. I use a circular motion that is the size of an American Quarter.
4. Ridges from the circular motion build up with repeated applications of polish. These must be removed using the larger fad with a 1 lb. cut of polished. Use a straight light sweeping motion over each rib. A little over-lapping is OK.
5. Always allow the polish to dry for several hours before resuming work with a different fad.
6. 'Spirit off' using the larger fad and a polish that is increasingly more dilute until a flawless mirror finish is achieved.
7. Or, if the spiriting off proves troublesome allow the finish to dry for a week and polish with rottenstone lubricated with mineral oil until you are satisfied.
Decorative tip of the End Clasp

I decided that spiriting off would be too tricky on these narrow ribs. I reduced the amount of shellac to a little less than a 1 lb. cut and made several passes. I allowed this to dry for several days.  Then I rubbed the finish with rottenstone and mineral oil using a soft paper shop towel and Q-Tips for the difficult areas.

Future posts will describe the 1805 Giovanni Fabricatore in the Edinburgh University Collection of Historical Musical Instruments that I examined last month.
And a multi-post description of my construction of a Panormo guitar from a 1834 model.

All photo by the author.

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