Recreating original purfling

BY JANET STARCK-TOON Luthier based in Portland, OR, US

Makers reveal their special techniques

AUTHOR PHOTO DEB STONER. ALL OTHER PHOTOS MICHAEL JUDGE

Often the smallest details in the restoration process yield the most satisfying results. Recreating small sections of purfling that are missing, degraded, or have been poorly replaced is both challenging and fun. Replacement purfling also adds structural integrity to the plates and does not call attention to edge, corner or button replacements or to itself.

The first step of identifying what specific woods, cuts of woods and materials were used in the original purfling can be the most difficult. Sometimes additional analysis is required. On a cello by David Tecchler (right), the purfling material was dyed beech, with metal for the centre strip. I sent a very small sample off to a metallurgical laboratory. The report supplied enough information to locate and procure bars of pewter that were of a similar composition. Making the replacement purfling (above) was difficult but ultimately successful, and was so much better than the lead solder that had previously been used to fill in the sections of missing purfling.

Tools and equipment used

Samples of walnut for comparison

1 In addition to the usual tools, for identifying the materials I find it helpful to use a 10X Optivisor, a 15X LED loupe and a UV light. I have on hand mounted samples of woods and their different grain orientations for comparison. Once I have formed an opinion of what I think the original purfling is made from, I seek additional input from colleagues and resources for confirmation. Past in-depth articles on specific makers in TheStrad have been invaluable.

The original purfling in need of repair

2 Recently I had the opportunity to redo some poorly replaced purfling and a back-plate button on a cello by William Forster II. I examined the original purfling and decided that it was made of poplar cut on the quarter, sandwiched by two ebony strips. For confirmation I asked colleagues and consulted the reference book The British Violin: 400 Years of Violin Making in the British Isles by Tim Baker, John Dilworth and Andrew Fairfax.

The reticle shows the width of the purfling is 2mm

3 I measured the thickness of the strips in several places on the cello using a small microscope with a reticle. If the purfling is handmade, the thickness of the individual strips often varies. I like to mimic those subtle variations.

New ebony and poplar cut for the repair

4 For the ebony strips, I sawed the sides off an old used fingerboard with a bandsaw. The poplar strip was made from a chunk of wood that I first cut on the quarter. I thicknessed the strip using a hand plane.

5a. The neck and original purfling have been removed

5b. Tracing the purfling line on to acetate

5 One sided frosted acetate is a wonderful material that I use daily for wood replacement guidance, and for counterform patterns. After removing the non-original purfling with a purfling picker (5a), I traced the line of the empty purfling channel on to a piece of acetate (5b). Using double-sided sticky tape to adhere the acetate to a piece of Baltic birch plywood, I bandsawed and spindle-sanded along the traced purfling channel arc, and created my counterform to laminate the strips of wood together. Then I applied Scotch tape to prevent the purfling from sticking to the counterpart.

The new purfling is clamped and glued

6 It is helpful to place the counterform and purfling strips on a flat surface covered with wax paper. This allows gravity to keep the strips level with one another while gluing and clamping. Having done that, I left the purfling to dry overnight.

The purfling strip can be seen in the lower right of the picture

7 After laminating the purfling, I used rubberised shelf paper to hold it in place while planing it to a height just proud of the depth of the channel.

8a. The original purfling is trimmed to match the replacement

8c. Purfling clamped in place

8b. Ebony scraped on poplar

8 To ensure exact placement of the purfling, I used a micro chisel to trim the original purfling to the same angle on both sides. The angle that is undercut acts as a stop and the beginning point for fitting the new purfling (8a). I scraped the ebony on the new purfling in order to line up the poplar middle with the original (8b). After trimming and scraping it to fit on both ends, I applied hide glue and clamped it overnight (8c).

9a. The purfling is trimmed

9b. The finished repair

9 When it was dry, I used a gouge to trim the new purfling flush in the channel and with the original purfling (9a). An agate burnisher helped provide a nuanced surface. I finished off by using clear varnish and coloured pigment to blend the new and original together (9b).