Surface Treatment

The beauty in things lives in the soul of the observer.

David Hume (1711 – 1776)

There are several methods for treating the instruments's surface. I use these to finish my guitars... wax, open-pore matte lacquer, high gloss finish with nitrocellulose or polyester lacquer and shellac.

The material chosen will influence the sound of the guitar, and the amount of surface coating used is vital because wood changes its dimensions with the varying relative humidity. In order to withstand these movements, the surface treatment must be elastic. Last but not least, each type of surface treatment has a certain weight to it, and using too heavy a finish can make the soundboard sound dull.

Wax
In order to seal the pores of the wood to minimize any dirt getting into them, I prime the guitar, for example with shellac. Then I apply wax, which results in a beautiful, semi-gloss surface which can easily be touched up. This is the most minimalist finish I offer.

Open pore matte lacquer
In this case I don´t fill the pores of the wood. Only two coats of a lacquer are required for a open pore matte surface treatment: one to prime, and then a second coat. This treatment is a bit more robust compared to a wax finish, however it is also a little heavier. 

High gloss lacquer
In order to achieve a high gloss finish, all the pores of the wood must be completely filled. With most types of lacquer, the final coat is sanded with an extremely fine grit and then polished. This surface treatment is much thicker compared to wax and matte lacquer options. For this process I use two different types of lacquer: nitrocellulose and polyester.

Nitrocellulose lacquer dries through the evaporation of the solvent contained in it, and this process allows the lacquer to meld into any lower layers. This means that a good bond can be achieved between old and new lacquer, which is important for repairs and restorations. However, because it has a low count of solid particles, many coats of this lacquer are required.

I mostly use polyester based lacquer. This is a two component product consisting of hardener and lacquer, and has a slight bonding delay which means that much more care must be taken during application as mistakes cannot be easily rectified. However, because it contains high volume of solid, a beautiful high gloss finish can be achieved with only five thin layers.

Shellac is the most highly-prized finish for any guitar.
The Kerria Lacca insect inhabits a range of host plants, living off their saps. The lac insects then excrete a kind of wax through special glands, and wich they use to make their cocoons. Once the young insects hatch, the cocoon falls from the tree and is further processed, until it lands on my workbench and is dissolved in alcohol. I then carefully apply the dissolved lacquer with a polishing pad, using approximately 20 coats.

I do not know any other type of lacquer with which you can achieve a high gloss finish which is only 30µm (micrometres) thick. From an acoustic point of view this means that the shellac lacquer is the best possible option to finish a soundboard with.

Of course shellac has also disadvantages. It's very sensitive to physical influences, perspiration or even the body heat of the guitarist can soften the lacquer. For this reason, I only apply shellac to the soundboard of my guitars.

German / Spanish construction

If you always play by the rules you will miss a lot of fun.

Katharine Hepburn (1907 - 2003)

A very basic decision and much-discussed topic is the subject of German or Spanish construction.

Both methods can by carried out in high or low grade. I'm of the opinion the style is not a quality feature.

A brief historical review: ... With the conquest of 1805 by Napoleon, Vienna became a cosmopolitan melting pot. In hope for a better life, many people now moved into this thriving metropolis. For 50 years, until the March revolution and the arrival of Empress Elisabeth I. Vienna was the center of the guitar world. For luthiers there now was a lot of work and some used this opportunity to make a name for themselves. Much knowledge was developed and carried into the world, namely to Germany. This established the so-called "German construction".

Let's look at Spain during this time and we see many political upheavals which make life difficult in the country. The luthier worked with minimal tools in their tiny workshops. And thanks to mother of invention the Spanish luthiers were able to replace vises commonly used today with a single string. This tool is one of the most important in my workshop!
While the guitar experienced a boom in Vienna with everyone inclusive nobility, it was "only" the instrument of the common folk in Spain and rarely seen at the royal court.
Simultaneously with the mid-19th century collapse of the guitar scene in Vienna, the rise of the guitar building art began. With Antonio de Torres pioneering this, the "Spanish construction" became known throughout the world in the Spanish guitar.

So what is the difference between the Spanish construction and the German? Essentially, it is how the guitar is assembled.

In the Spanish construction all components such as soundboard, neck, sides etc. are made. Then the neck, which extends into the body, is glued to the soundboard. Both are fixed together onto a "Solera", which defines the exact neck angle. On this Solera the two side halves are glued onto the soundboard and into two slots of the neck. Once the sides are outfitted with various small components and are adjusted to the convexity of the bottom, the body is closed with latter.

Mostly I build "Spanish" whilst using many elements of the German construction ...

Here, the body and neck are made independently and then joined together. Other differences include the nature of the sound board convexity, the neck-head connection bracing etc.

Soundboard construction

Only he who is different from the broad mass is able to stand out from it

Chinese wise saying

On a guitar energy is transposed only for a split moment to the string, which is then supposed to vibrate well and long. This means the soundboard must be constructed so it is dampened minimally.

Weight is another parameter. Due to the string tension (only nylon) of a mere 40-45 kg's, the available energy to make the guitar resonate is clearly defined. In relation to the soundboard...the lighter it is, the easier it can be brought into vibration. However, the soundboard must still be able to withstand the 45 kg string tension!

At the moment there are three soundboard structures going around the world. On the one hand the traditional bracing with over 150 years of history. Then the lattice bracing by Paul Fischer, made especially popular by Greg Smallman and thirdly the Doubletop-Soundboard established by Gernot Wagner.

The traditional bracing
The soundboard has depending on the material composition and the vision of the luthier a thickness of 2mm and 3mm. It is reinforced with the aid of five or more braces arranged in a fan shape. Thus, the soundboard can withstand the string tension.

The traditionally built instruments of mine are in comparison to the Lattice-Bracing guitars a bit harder to "open up" as more force is needed plucking. Once they start singing though, then you have incredible variety of timbres especially in combination with a spruce soundboard. These guitars are not overly loud, yet can carry their sound next to loud instruments or a choir and be heard into the last corners of a room.

Lattice-bracing
As the name suggests, the braces are positioned in a lattice arrangement. This way you can reduce the thickness of the soundboard down to 1mm and reduce the weight substantially. The idea of the lattice-bracing is a loud instrument. Yet often this additional volume is at the expense of varying timbres. I have seen guitars made in this construction which are very loud when you are close, but cannot fill a concert hall.

After long observation and reflection I have manufactured the first guitars combining the advantages of a traditionally built and lattice braced instrument in 2014.

Doubletop
In this construction, a 0.6mm thin outer layer of wood is bonded onto a honeycomb mesh. Then a inner layer of 0.6mm wood is glued to this so that a type of sandwich arises. Meanwhile, a number of varying construction methods of this type have been developed. The idea behind it are the same as lattice-bracing: reduce weight. Yet the problems are similar as well. The biggest advantage is that the guitar always sounds the same, even when changing relative humidity. This is the primary advantage for players who need to travel a lot.

The soundboard is indeed an essential detail of a guitar, yet just one detail. Only in combination with all other parts can a guitar receive the desirable properties so desired. The way how the sides, the bottom, the neck or the shape are designed affect the final result significantly

Bottom and sides

Perceiving things is the seed of intelligence

Laozi (died 531 B.C.)

The bottom and sides have more influence on the character of a guitar than most people imagine. The body construction, the type and quality of the wood influence the sound of a guitar. These are a few details which enable me to build a instrument for each individual guitarist.

I see two different directions amongst luthiers in relation to the tasks a bottom and the sides have to accomplish. Some want to have the bottom work together with the soundboard. It is then built very light, possibly even from spruce and braced very extensively.
The others only want the soundboard to work and construct the bottom very stiff and heavy. Thus, the vibrations are reflected very well.
The same concepts are applied with Sides and neck.

Using different construction methods and modern materials make it possible to build extremely rigid, heavy or light. But only the correct interaction of all components finally determine the qualities of a guitar.