Using Airbrushes
For Tone Spray Effects

This cherry salad bowl features a light
reddish-brown tone spray to enhance
the natural cherry colour

Overview: If you've never used an airbrush before, you're missing out on using a very versatile and efficient tool in your studio. From spraying finishes on smaller projects to using them for decorative embellishments, airbrushes can serve you well in many different areas. One of my favorite uses for an airbrush is using it to create delicate coloured effects on finished projects. A tone spray is simply a light spray finish coating that is coloured by various means to enhance the colour and look of a particular piece of wood.

Oil colours can be
used to easily create
these delicate colouring effects

This effect can warm up the colour of the wood, or add a bit of sparkle depending on how you spray the piece. For example, you can add a slight red-brown to Mesquite to warm it up a wee bit, if your blank is on the lighter side.

Or, you might want to add a faint yellow overcast (where the color is sprayed over the entire piece) on a piece, to enhance the yellow or orange colours in the wood. You're only limited by your imagination when using an airbrush.

You can also use an airbrush to add decorative enhancements like dyes, stains, micas and mother of pearl nacre (for subtle highlights), or you can use an airbrush to accentuate certain areas on the piece that would be difficult if not impossible with any other method.

For example when colouring burrs, an airbrush can be used for pinpoint colour control, allowing you to colour specific areas, or enhance them without effecting adjacent areas.

Pearlex pigments can produce stunning effects when used in tone sprays

For example, if you have some Red Stain Box Elder where the red colour fades away in certain areas or is too light, you can use an airbrush to add a blush of red to these areas. If done properly, it would be difficult if not impossible for anyone to know you had altered the piece. Or, you might want to add randomized black lines to a spalted piece of wood to make the spalting zone lines more distinct, or numerous.

Airbrush Quick Tips

Airbrushes can be used to paint soft edge lines, or cover larger areas with an even coating. You can also use them to paint straight edge lines, with proper masking and fade colours in and out of specific areas with soft transition lines. They are also great for spraying tone finishes and custom finishes on smaller projects as well as repair work on previously finished pieces that have been damaged, or are in need of touch-ups. There are two basic types of airbrushes, single action and double action.

Single Action Airbrushes: When you push down on the trigger, you get both paint and air from the tip. A separate adjustment knob controls the amount of paint you spray. Single action airbrushes are limited by the fact that you must stop periodically to adjust the amount of paint flow. For this reason, many people prefer double action airbrushes.

Double Action Airbrushes: When you push down on the trigger you get air, pulling back on the trigger gives you paint. The amount of paint you apply is determined by how far you pull the trigger back. This gives you much more flexibility when spraying than a single action airbrush, but requires a bit of finesse to operate correctly. By varying the distance from the surface, you can control the spray pattern when using both types of airbrushes.

This Vega double action airbrush kit is a good all around airbrush for woodturning embellishments

If you're just getting started using airbrushes, look for a good-quality single action model. While they are more limited than a double action model, they are easier to use for many new users. If you already have a compressor in your studio, you can use that for your air supply, or you may want to purchase a dedicated compressor for use with your airbrush.

If you prefer, pre-filled cans of nitrogen or carbon dioxide are available for use as an air supply. The advantage here is you don't need a compressor at all, but the cans can get expensive if you use them frequently.

After you gain some experience, look for a good-quality double action airbrush (paint volume and air are controlled with a single lever). Most entry-level airbrushes at art supply stores are inexpensive and work well. If you will be using a small compressor to supply air, look for a unit that offers a supply reservoir. This will help to provide the airbrush with a constant even flow of air without requiring the compressor to run continuously and will produce smoother finishes than using tank-less, diaphragm style compressors.

Moisture traps are available to eliminate moisture in the supply air and are easy to install on the supply line to the airbrush. If you have a good regulator on your compressor, you can use that to set your preferred supply pressure. Small pressure regulators are also available that can be used on the end of the air supply line to insure correct airflow and are convenient to use.

Remember to work in a well-ventilated area and wear a good quality respirator with an organic vapor cartridge specifically rated for the type of finish you will be spraying. Also, I like to wear a full-face safety shield as an added precaution against spray mist.

Using An Airbrush

I use professional grade airbrushes that offer several tip sizes. If you really get into using an airbrush, the professional models offer better spraying action and more choices in tip sizes, but can cost several hundred dollars each. The largest of these tips can spray most oil and lacquer finishes without thinning.

However, I've found that I must increase the input pressure and use a larger needle if I want to spray some thicker viscosity finishes. Most input pressures run as low as 15 or 20 psi, while some materials up to 60 psi or more to spray correctly. If you have an airbrush, you know that many factors influence the quality of the sprayed pattern including the viscosity and type of subject material, size of the needle tip, pattern you wish to create, distance from the surface and so on.

When spraying small items, a gravity feed, or side feed reservoir works well and offers easier cleanup than the larger glass suction cup reservoirs. If you will be spraying larger items, using a small glass spray cup will offer extended spraying time. Some models do not offer additional spray cups in the beginner's kit, but you can simply refill the reservoir on larger jobs. If you will be working in very tight quarters, airbrushes are available with an internal cup reservoir that fits inside the body of the unit.

Creating A Tone Spray Effect

I typically use either an oil finish, or a lacquer finish for tone spraying. Oils can be tinted very easily however, if you want to spray delicate pastel colours you will need to get oil that is as clear as possible. Many oils have an amber cast and will compromise your delicate tinting effects.

In fact, any colour work will yield better results with a clearer oil base. This is one reason that many artists use clear lacquers for tone spraying. Tone sprays can create very provocative, yet delicate effects that can greatly enhance an otherwise plain timber.

Refined linseed oil makes an excellent base for tone sprays where an oil finish is desired

Colour wheels are an inexpensive tool to help you learn about working with and blending colors

I prefer high quality artist oil colours (available at any art supply store) in a purified linseed base for this type of work. You need to be aware that many colours are not permanent and will fade.

Read the manufacturers information and only purchase colours that the manufacturer says are permanent. Also, the highest and most vibrant colours come from the most expensive pigments. If you are using only small amounts of colour, you may wish to purchase the dry pigments and grind them yourself before use.

A less labor-intensive approach is to use manufactured artist's pigments. These are nearly as good as grinding your own each time you need them. Be aware that some of the pigments in oil colours can be toxic. Therefore wear gloves or insure that you thoroughly clean your hands after working with any pigments.

To colour the oil for tone spraying I add a small amount of artists pigment, mica or pearl nacre to the oil and mix it thoroughly. Since colour work is highly variable in nature, I always test the colour on a scrap piece of timber of the same species. If it's too light you can simply add a bit more pigment, if it's too dark, you can add more oil to lighten it up.

Also remember, when you spray the toned oil, you control the ultimate colour by the number of coats of finish you apply. One or two light coats may be almost imperceptible, whereas numerous coats will produce a more pronounced colour change.

It's a very easy and simple process to control and the results can be quite provocative. I typically spray on a few light coats of the toned oil and let the piece dry thoroughly overnight. The next day, I check the colour and if it needs more, I spray on a few more light coats.

Acrylic colours can be used to create tone sprays when working with water-based finishes

Watercolours can also be used for tone sprays when working with water-based finishes

Another option for creating tone sprays is to colour your sanding sealer, instead of the finish and then apply clear oil over the top. If you are not sealing the work first, then consider this approach.

However, you can also get good results colouring only the oil in an "alla prima" fashion. Experiment with this technique on a few of your pieces. Once you get started using airbrushes, you will be hooked and your artistic options will be greatly expanded.

Liquid acrylics are available in numerous colours, including pearlescent versions

Liquid airbrush colours may also be thinned down to use on with coloured finishes

Safety Note: Always follow all manufacturers safety instructions before working with your lathe, or any of the tools or products you may use. If you are unsure about any operation, obtain competent professional instruction before proceeding. Use and wear all necessary safety devices during turning and observe safe woodturning practices to prevent accident or injury.

Steven D. Russell is a professional studio woodturner, teacher and writer. He has written numerous articles for international woodturning magazines, which have been published in more than 78 countries around the world. Steve has demonstrated in numerous cities across the United States. His studio, Eurowood Werks, specializes in bowls, platters and hollow forms with unique visual and tactile treatments.

Steve is also the current and founding President of the Lone Star Woodturners Association, Inc., an AAW member chapter. The LSWA is a 501(c)3 non-profit educational organization dedicated to teaching and demonstrating the art and craft of woodturning.

Steve is also a featured writer for the Guild of Master Craftsman's "Woodturning" magazine, published in London England. Woodturning magazine is the world's leading magazine for woodturners. Look for his articles covering technical topics, or project based articles in an upcoming issue.