The purfling

The purfling is the inlay which runs around the edge of the top and bottom plate. It is usually a "sandwich" of three sheets of wood glued together. Other materials such as hardened paper are also used today as the cheapest options but these should generally be avoided. In Fig. 1. you can see the three distinctive layers comprising the inlay of total thickness of 1.2 mm. The "A" layers are 0.3 mm and the "B" layer is 0.6 mm thick. In the olden days, the bright layers might have been maple and the dark one ebony shavings. Today, most makers buy the purfling strips premade.
  1. Make sure the thickness is even, typically about 1.2 mm and the height is about 2 mm throughout.
  2. Create a slight bevel at the bottom edges to allow for and easier insertion into the channel. See Fig. 1.

Marking the purfling channel
  1. Make sure again that the plate outline is perfect, without any bumps and that it flows gracefully and naturally in accord with the violin copied as well as with what you consider natural.

    This outline will now serve as the guideline for the purfling marker and therefore for the purfling channel itself. Remember that the final overhang is about 2.5 mm for the violin we are making, except for the corners, so finalize the outline just a little over that.

    If you leave the overhang too large now, the purfling will follow it, making any reduction later very difficult.
  2. Carefully observe the distance of the purfling channel from the edge in the copied instrument. Normally it is about 4 mm in but its final position is also influenced by the length and width of the top and bottom corners. The purfling mitres must meet at just the right position to form the tip and the bee sting.

    The corners are constructed as in Fig. 2 and 3. The red line indicates the outline linearly inset by 3.7 mm. The green line shows the lines altered so that they form a sharp tip and meet at the correct distance from the corner`s end. The black line is the final approximation taking into account the preference that the purfling in the corners should be leaning a little, following the bee sting. The bee sting itself is in blue and flows naturally towards the inner tip of the corner.
  3. Now you need to set up your purfling marker based on the previous observations. If using a double edge marker, make sure the width of the resulting channel is enough for the purfling to slide in easily. When gluing, especially with spruce, the wood tends to swell, and any tight fit now will become impossible then. To test for that, use a piece of spruce, make a series of marks and cuts, scoop out and see if the purfling strip fits in nicely.

    The position of the purfling channel in relation to the edge and the corners can be tested first on the opposite side of the plate.
  4. Everything adjusted, you can start marking the purfling channel. Especially with spruce, it is important to first go very lightly, otherwise the blades tend to get misaligned by the wood grain having the tendency to go along with it. It is also important that you hold the purfling marker at a constant, perpendicular angle.

    Bear in mind that you are just marking the channel, not actually cutting it at this point, so create a rather shallow cut but with great precision which will later serve as a guideline for the cutting knife itself. Again, go light, or you will loose precision. Repeat, until you are sure the groove is deep enough to guide the knife.

Now the corners. Measure the distance the tips of the purfling in the corners ends from the tip of the corner itself. With the Messiah this is about 3.5 mm. Lightly Mark this distance on each corner. Start lightly marking the channel in each corner always starting from the C bout side. The lines should meet at the marked distance from the corner's tip. If they don't, adjust so that they meet there. Remember that the tip leans a little towards the C side so the oposite side can be shaped accordingly.

Cutting the purfling channel

The cutting itself is done with a knife. You can use your regular knife with bevels on both sides, or you can try a knife with just one side bevelled, which makes the cutting of flat, perpendicular walls a little easier.

Go with light strokes followed by heavier ones. Avoid undercutting - the resulting walls should be perfectly perpendicular.

At this stage the purfling channel should be about 2 mm deep, assuming the thickness of the plate edges is a little over 4 mm, so make controlled cuts going no deeper than that. This depth will later get reduced, because of the fluting to about 1 mm. Consult Fig. 4 to get an idea about the channel's position.
  1. Start cutting at the top or bottom of the plate where the grain orientation makes it easier to make precise cuts. You will cut the channel along the whole outline except for the corners, which will be dealt with later.
  2. Use a purfling pick to remove the waste material.
  3. After you have finished the outline, start working on the corners. I would suggest using a smaller knife, because it allows more control in the tight curves and the bee sting.

    Be extremely careful with the inner tips at the corners, which are easily chipped off, especially in spruce.

In Fig. 5. you see the finished channel.

Category: Front