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Active electronics example

The picture above shows a parametric equalizer installed on a printed circuit board and mounted in the control cavity with spacers. The 9-volt battery is fastened in the control cavity using special holders. There are also separate battery compartments with lid that you can buy to make access to the battery easier. Make sure that all parts of the electronics are fastened safely in the control cavity so that they remain in place even when exposed to shaking.

pickguard. The individual foils are connected with each other so that only one lead is required for each area. Another lead connects with the spring cavity of the tremolo unit to ensure the strings are grounded as well (1).

Electronic cavity covers made of metal should also be grounded. Do so by gluing copper foil on a wooden or plastic cover and connect the foil to the ground point of the jack with a wire. Make sure to leave the ground lead long enough so that you can take off the cover if you want to. Grounding the control cavity cover in this way reduces hum, which is important as any interference is passed on to the electronics of the guitar via the body of the player.

The guitar is ready for finishing if after this first provisional assembly everything is fine. Look out for the following:

-Can all parts be fitted easily?

-Is the weight of the guitar distributed evenly and does it sit comfortably on your body?

-Is the neck contour fine or does any wood have to be removed in one place or another?

-Is it possible to set a low string action?

-Does the circuit work?

-Does it sound as hoped for?

If this is the case, disassemble the guitar again and store the individual parts in a safe place. The small screws needed are best stored in a magnetic bowl

Preparing for finishing

The time has now come for a kind of “cosmetic surgery” on your guitar by giving it a protective coating that will highlight the beauty of the wood. If you have so far worked with great care and used highly-figured wood, there is really no reason why you should want to hide the grain by painting it; wood is, after all, a beautiful material whose beauty increases with age. But tastes differ and you might well prefer a colored finish or a body with an unusual motive.

In theory, your guitar can also be left without a finish. Unfinished guitars will, however, sooner or later turn greyish-brown in all areas where they are handled, and this is not really a color particularly pleasant to look at. The neck, which is constantly exposed to hand sweat during playing, would be particularly affected by this. In practice, it is therefore virtually inevitable to apply a protective coating, not least because this enhances the natural beauty of the wood and makes it easier to keep the guitar in a good condition. Another argument in favour of finishing a guitar is that this slows down the moisture exchange considerably; with a protective coating the wood is less “active”. The

Finish-sanding

The first thing to do before applying the finish is to fine-sand the surfaces of the guitar. Always sand in the direction of the grain, starting with 150and continuing with 220-grit paper. If you want, you can use even finer paper, but the difference will be hardly noticeable on the finished product. Sanding can stop when no more scratches, dents or other uneven areas can be detected when inspecting the wood very closely from all directions and against the light. This is extremely important, so do the checking really carefully: any blemishes not dealt with at this stage, no matter how minor, will come out much more clearly later on an otherwise perfectly smooth and glossy surface. Surface imperfections are easier to detect by wiping naphta or lacquer thinner on the wood surface. The wiped-on liquid will evaporate after some time and reveal any defects that may still be left.

Never use steel wool if you intend to use water-soluble products for finishing: no matter how well you clean the surface, there will always be tiny bits left which will begin to rust and cause black spots on the surface. Use a sanding sponge or pad or synthetic steel wool instead.

Masking

All parts that are not to be finished, such as the rosewood fingerboard shown on the right, have to be carefully masked. The sides of the fingerboard can be sprayed as well or masked as shown in the picture.

Stains made from bark

You can make your own “environ- mentally-friendly” stains from bark. Such stains would be particularly well-suited for an electric guitar built in an “environmentally-friend- ly” way, one which is perhaps even played over an amplifier powered by solar (or maybe some day even cosmic) energy. To make bark stain you need small pieces of bark from branches ideally sawn off trees between May and October as this is the time in which trees grow and produce sap. The sap content of trees is said to be highest in times of waxing moon (i.e. between new moon and full moon); these times are therefore ideal for collecting bark. When you have got enough bark, fill a glass container (with lid) about two-thirds with bark pieces. Then add a 5 per cent hot soda solution, i.e. 1 part of soda powder and 19 parts of water, so that all of the bark is covered, put the lid on the container and leave the solution to stand for three days. After that time bring it to the boil and leave it to simmer for about an hour. Use an enameled pot for boiling - the stain must not get in touch with metal! After about an hour filter the liquid through a cloth into a glass container (with lid) and then leave it to cool. Such bark stains often give different shades of brown; what exactly the eventual color is going to be also depends on the type of wood that is stained.

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Staining

When a wood surface becomes wet its fibers swell, causing the initially smooth surface to feel rough again after drying. To prevent this happening or at least limit this effect when a wet finish is applied, wet the surface with a cloth or a sponge, using tepid water. Then wait for about half an hour until the wood has completely dried, before sanding the surface with 220-grit paper. Repeat once or, if you like, twice. Such “sponging” or “whiskering” before applying the stain or finish is particularly important when using water-based products for finishing as these swell the fibers particularly strongly. Finally brush or vacuum off any sanding dust from the pores. By gently wiping the surface with special cloths even very fine dust particles can be removed. Such useful, slightly adhesive cloths are available wrapped in foil from paint stores.

If necessary at all, you can now start applying the stain. Staining emphasizes the wood's grain and gives it a particular tone. Applying stain directly to bare wood can, depending on the type of wood, impart a warm tone to the guitar: yellow, brown and slightly reddish tones applied moderately support and enhance the natural beauty of the wood. Stains of the same type can also be combined with each other for custom colors. The lightcolored and rather uninteresting pattern of ordinary, straightgrained maple in particular is improved by staining.

Aniline dye stains are easy to use, give more even results and make coloring wood generally easier. They come in the shape of alcoholor water-soluble powders and are available in a wide variety of colors. Since only very small amounts of them already give very intense colors, it is advisable to add only very small quantities of powder at a time to the solvent, best with the tip of a knife - or else you might end up with a darker stain than intended. Differently-colored stains can be mixed together for custom colors.

Dissolve water-soluble powder in normal or, better still, in destilled water. I use ordinary, cold tap water. Use denatured alcohol for dissolving alcohol-soluble powder and mineral spirits or lacquer thinner for oil dye. Always test the mixture on a piece of scrap wood first and also put on an oil or lacquer-finish to get as realistic an impression as possible. Even the type of finish used - water-base or lacquer - will make for a difference in color. A lot of guitarbuilders apply a wide range of different colors and intensities on a piece of scrap wood and then oil or lacquer-finish it. This can then serve as a useful guide for deciding what tone to eventually go for.

In the picture on the left (1) you can see me applying vintage amber stain directly to maple. This stain is to make the wood appear yellowish and resemble a maple neck which has aged

over several years. The stain is applied evenly all over the wood with a cloth or a sponge and is then left to dry. Don't be fooled by the dirty-greyish color of the dried stain: it won't begin to “shine” until it has been oilor lacquer-finished. All water-based stains and lacquers raise the wood fibers. This is not that much of a problem on surfaces finished with clear lacquer: simply sand them with fine-grit paper. If, however, a colored coat is applied, the evenness of the color tone will be changed by the rising wood fibers. This effect can be limited by wiping the wood with a wet cloth and sanding the surface after drying, as described above. Repeat several times if you like. Surfaces treated in this way will be far less rough after the application of stains or water-based finishes. Alcohol-based color stains and a few other special stains do not raise the fibers. Stains can be sprayed, wiped or brushed on.

Filling the grain

Filling the grain of open-grained timbers is an important measure to take to get a competely smooth surface. Such surfaces, which should ideally mirror like glass, are very common on guitars of all kind and buyers often expect this to be the case. Some types of wood such as maple, basswood or alder have a close-grained surface to which a finish can be applied directly. Other types such as oak, mahogany, ash, walnut, rosewood and others have an open-grained structure, i.e. larger pores that are easily recognizable with the naked eye. These surfaces require filling of the pores before any smooth finish is applied.

But keep in mind that using a grain filler is not an absolute must; not using one will, for instance, preserve something of the natural beauty and feel of the wood. But if you want a mirror-flat surface on open-grained woods, there is really no way around grain fillers.

There are special hard-curing grain fillers, or paste-wood fillers, for this purpose which speed up finishing and save material into the bargain. If no grain filler was used, the thin coats of finish would keep soaking into the pores during drying and a lot of coats would have to be applied and a ridiculous amount of material spent. All this can be avoided by using a grain filler, which contains quartz or silica dissolved in an oil/ varnishor water-based finish. They are therefore not the same as wood putty, which uses wood dust as a bulking agent.

Grain fillers come in thick pastes which, mixed with water or mineral spirits, form a creamy substance that is then applied with a plastic spreader or a coarse cloth such as burlap. Apply it in any direction you want and push the filler into the pores. Then remove the excess by rubbing across the grain with a coarse cloth. Leave the filler to harden and then repeat this process

Sunburst finishes

Sunburst finishes also give very attractive surfaces; with this finishing technique a gradual transition in the color of the body (from darker at the edges to brighter towards the center) is obtained. Sunbursts are easiest to apply evenly on a slightly wet surface, but if you want to save time you can also apply them directly to the wood. If you should have applied too much aniline stain, simply wipe off the excess. Aniline powders can, however, also be added to lacquer later to give a colored coat between two coats of clear lacquer that is totally different in appearance from a coat applied to bare wood.