French Polish is a shellac based finish applied by hand with a special pad. With all of the previous work on the guitar – fine sanding, sealing, pore filling, re-sealing – each surface has been made as flat, smooth, and pore-free as possible before beginning to French polish the shellac. I brushed on a thin coat of Zinsser’s SealCoat, a dewaxed shellac that can be used under any finish. I have had a go at french polishing after watching your DVD and using the kit, and I am really amazed at the result. Applying initial polish coats with a brush; flatting and finishing with the traditional French polishing rubber.
The stages at which the polish must be reduced in strength, and exactly when to introduce more or less alcohol and oil are explained in detail. When doing the smaller surfaces on the neck ensure that enough time is left between application strokes to allow the shellac to dry. You will find three grades of shellac flakes available – blonde (pale), amber, darker amber. A French polish finish is less durable than other treatments and is more susceptible to damage from heat.
I was asked by several flamenco and classical guitar owners if I would strip the polyester varnish off the soundboards of their factory made guitars and replace the finish with a French Polish. The polish is applied by opening the pad and charging the cotton wadding with approximately 4 tablespoons of polish. Ensure that you avoid dipping the rubber directly into the polish and do not pour it onto the sole of the pad.
A carpenter trained in French polishing will also be able to carry out these ‘˜spot’ repairs. This opaque, milky appearance is the result of the natural waxes that are found in shellac. I generally go through a phase of adding shellac, switch over to straight alcohol for a time, and go back to shellac. Holding the polisher in one hand, open up the linen covering and pour pure polish onto the pad liberally. When using too much pumice or too much shellac it can sometimes cause veil and deposits on the surface.
It is understood, though, that the same procedures and sequence are used to completely finish each surface of the guitar. If using a polish, it is also essential to verify that the pH of the polish is not in the higher range, for alkalines will degrade shellac. A variety of types of polishes are used, mainly shellac and tree sap based and the routines can also vary, but the final effect looks approximately the same. As every new, extremely thin coat of shellac is applied, it’s alcohol solvent melts the uppermost part of the hardened shellac film already on the furniture.
Concentrate the French polishing in a limited working area – ¼ of the top, ¼ of the back, or ½ of a side – and polish that area thoroughly before moving to finish more area. For example, french polishing, which is a method used for applying a highly polished shellac finish primarily to small table tops, is a technique used successfully only by the most experienced workers. Also remember that heat resisting mats for your table are not a license to put 200 degree pans on. You will damage your table, the mats resist heat they don’t repel it! French Polish, a shellac-based finish (and a method of application) is the typical finish on most fine furniture built before the 20th century.
It is true today as well that spray lacquered finishes are quicker and easier to apply and probably more durable, however the french polished surface is more forgiving in that it can be repaired more easily and is, to my mind, more beautiful in that it lends a depth and lustre which spray finishing cannot. It was considered the best way of treating fine furniture and was also widely used for treating musical instruments made out of wood, such as pianos and guitars. The colour of the shellac varies according to the species of tree the beetle lives on, and ranges from a deep garnet through orange to pale yellow.