Art Education: Air Tips

What exactly is an airbrush and how is it used?

The first airbrush was a hollow pipe that prehistoric man used to blow pigment onto the stone walls of his cave. The basic principle remains the same today. Air under pressure is used to atomize paint and blow it onto a surface. The advantage to this method of paint application is that the artist need never touch the item being painted, therefore the applications are unlimited. Abner Peeler invented the first modern airbrush in 1878 to mimic the fine dot pattern of photographic images. In 1893 Charles Birdick patented the Aerograph, thus early airbrushing was known as Aerographing. By the late 1890s the trend of sepia toning photographs made the airbrush a popular tool for such coloring. There were actual sweat shops with row upon row of technicians airbrushing color on sepia photographs. The original airbrushes were very complex, with almost as many moving parts as a Swiss watch, and were difficult to maintain. Over the years the airbrush has become simpler and much easier to use and service.

There are only three basic components a beginner needs to begin airbrushing, besides the paint and the object to be painted. These are the airbrush, an air hose and an air source. The air source can be as basic as a can of compressed air. Air cans are less expensive for short term use, but for extended use it is far more economical to invest in a compressor, which we will discuss later in this article.

Airbrush Trends

In the last few years the stigma of an airbrush being a mechanical tool for graphic artists has been replaced by a fascination with its potential. For a while the graphic artists themselves turned away from the airbrush in favor of computer graphics, but as all their work began to look the same, an airbrush revival began, due to its ability to allow unlimited creative artistic expression. There are now many applications for airbrushing that were unimagined a few years ago.

An airbrush does not touch the surface being painted, which allows the artist to paint on objects of almost any size, shape or texture. T-shirt airbrushing has long been a hit on the coasts, and at fairs and shopping malls. Automotive, motorcycle and bicycle airbrush customizing has continued to grow in popularity. Ceramists airbrush pottery, hobbyists airbrush models and model scenery, and taxidermists bring animals back to life. Muralists create masterpieces ten stories high. Fine artists increase their productivity by airbrushing backgrounds on their canvas before detailing the finished work with a brush. The most realistic portraits ever made were accomplished completely by airbrush, due to its ability to progressively layer translucent colors, giving flesh a depth not achievable by any other artistic technique.

It is interesting to note the different trends as unrelated industries realize the potential of the airbrush.  Lately we have seen a growth in popularity of fingernail airbrushing, and airbrushing cakes has become a creative trend. One of the latest and most fascinating is body art. This includes temporary tattoos, as well as body painting and airbrush tanning. Some of the materials to achieve these types of artistic expressions came from the motion picture special effects industry, which has long used airbrushing to achieve the aging of actors and the terrifying look of movie monsters.

The airbrush is by far the most versatile tool available to the artist. The only thing holding back many an artists’ masterpiece is the lack of knowledge of the airbrush’s great versatility. Where we go from here is anyone’s guess. How creative can you be? The next trend may be your creation!

What is the difference between a Single-Action Airbrush and a Double-Action Airbrush?

Single-Action: Single-action airbrushes have separate adjustments for air flow and paint flow. The air lever is pressed to allow airflow and the paint flow is adjusted by screwing the needle in or out while spraying on a test area before spraying the item to be painted. This allows for a precisely controlled paint flow and spray pattern. It is ideal for applications where specific line width or spray pattern is maintained.

Double-Action: With double-action airbrushes, the airflow and paint flow are both controlled by a single trigger, having a dual action. Down for air, back for paint. This gives the user the versatility of varying the line width, while continuously spraying on the surface being painted. This feature allows the user to be far more efficient, as well as creative in using the airbrush as an artist’s painting tool.

What is the difference between an Internal-Mix Airbrush and an External-Mix Airbrush?

Internal-Mix: With internal-mix airbrushes the paint and air come together inside the brush and exit through the same nozzle. This achieves the finest atomization of the paint and allows for greater control of the spray.

External-Mix: With external-mix airbrushes the paint and air come together as they exit their separate nozzles. The spray is coarser and less controllable. The advantage is that the external-mix system allows for the spraying of thicker paints, such as ceramic glazes and enamels. External-mix airbrushes are available in single-action only.

We usually recommend a double-action internal-mix airbrush due to its versatility. It is the system of choice for illustration, T-shirt art, fine art, automotive and most commercial applications. However, due to the external-mix low cost, durability, ease of maintenance and its ability to spray such a large variety of paint, this style of airbrush definitely has a strong place in airbrush market. Those using heavy mediums, such as ceramists, prefer the external-mix airbrush, as they use it for spraying thick glazes. The hobbyist often prefers the single-action internal-mix, as it is easier to operate and they mainly use it for shading. Although a single-action airbrush is easier to learn to use, it is better to learn on a double-action airbrush if that is what you will be using in the long run. It is much harder to relearn double-action techniques after learning them on a single-action airbrush.

What are the differences in Paint Feed Systems?

There are two basic paint feed systems. One is gravity feed, where a paint cup sits directly on top of the airbrush. The other is suction feed, where the paint container is mounted on the side or bottom and the force of the pressurized air passing through the airbrush sucks the color in.

Gravity Feed: An artist who changes color frequently and uses small amounts of paint will prefer a gravity fed airbrush. The more compact design also allows greater visibility for detail work. As the color sits directly on top of the needle, it has a faster response when paint lever is engaged. Illustrators, cake decorators, fingernail painters and those painting fine details prefer this design.

Side Mounted Suction Feed: A side mounted cup or jar allows the airbrush to be used in a vertical position, as the cup is rotated to remain upright. This style of paint feed is also called siphon feed. Many airbrush artists and illustrators prefer the versatility of this feature because the user can spray at any angle. No other design allows for this type of flexibility.

Bottom Mounted Suction Feed: This allows the use of the largest paint cups and paint jars. Artists using larger quantities of paint prefer this design. It allows for quick color changes by switching the color bottles. This is the most popular configuration and is used on T-shirts, murals, industrial and automotive applications.

Why are there different Needle & Nozzle sizes?

Some airbrushes are available in three sizes; one, three and five; others are designated by millimeters (.18-mm, 3.5-mm, 5-mm, etc.) which are achieved by using different tips, air caps and needles. The smaller sizes are for very fine detail work and relatively thin color. They are most often used for illustrations with watercolors, inks and dyes.  The medium sized airbrush are the most popular, especially for T-shirts, as they cover a good general range in spray width. The large sizes are for either broad coverage with a larger volume of paint, or usng heavier bodied paint. Large airbrushes are typically used for automotive applications, murals and other heavy applications. There are also many airbrushes esigned for very specific spraying applications.

The easiest rule in determining the type of airbrush you need is to be aware of what airbrush artists in your chosen field are using. You do not have to agree on the airbrush manufacturer, as it is most often a matter of cost and personal preference. What you need to be interested in is the basic airbrush design. If you wish to use the airbrush for shading purposes only, you do not need a double action airbrush. These airbrushes are for creative expression, fine lines to broad, without leaving the surface being painted. If you only want to shade with thick enamels and glazes, buy a single action external mix airbrush. Try to select an airbrush to meet your individual needs.

What are the differences in Air Sources?

There are several sources of propellant. Canned air is a simple, easily transportable source, but the cans are quickly used up. Air valves are available for tires, but the air pressure is uneven and debris in the tire can obstruct the brush’s air valve. Some professionals use large CO2 or nitrogen cylinders as their air source, which is excellent in some ways but they are heavy and must be refilled periodically. Most airbrush artists use a compressor as the air source because of its versatility.

Diaphragm Compressors: A vibrating rubber diaphragm pumps the air, similar to the air pump on a fish tank. The air is pumped through the hose directly to the airbrush. The pulsation of the airflow from the diaphragm’s vibration is most noticeable when painting work requiring fine detail.  Generally these compressors maintain 20 to 25 psi (pounds per square inch) when spraying, which is the minimum needed for airbrushing applications using thin color, such as inks and dyes, but are too lightweight for the more viscous paints. Diaphragm compressors are considered beginner compressors although they are adequate for cake decorating with food coloring and for cosmetic use.

Silicon Coated Piston Compressors: These are the newest and most powerful tabletop compressors, and are surprisingly quiet. They are available in a one piston unit and some can maintain up to 35 psi when spraying at maximum on most airbrushes. The two piston units are very powerful for their size and some can maintain up to 45 psi, which was previously unheard of from anything but a large commercial compressor. They are the new portable workhorses and usually come with a regulator, hose and moisture trap. They are now also available with a holding tank, which reduces compressor run time and eliminates any pulsation in the airflow. The two piston units can produce the air volume required for automotive or T-shirt applications, but they will not hold up to the 8-hour a day heavy use that related commercial units suffer. They are recommended for any part-time, portable commercial airbrush application or full time hobby, craft and art use.

Oil Piston Compressors: Oil Piston compressors designed for airbrushing use circulating oil, refrigeration-type motors which are very quiet; these are often called silent compressors. Size requirements depend on the type of airbrushing and the number of hours it will be used per day. Many commercial T-shirt artists use high pressure and require a heavy duty 1/2 hp. to 1 hp. compressor. The same size compressor would easily accommodate several illustrators. These units cost considerably more than other type compressors.

Shop Compressors: Shop compressors are the least expensive large compressors, but are extremely noisy. For airbrushing applications it is best to locate the compressor in your garage and run an airhose through the attic to a regulator in your studio.  It is not recommended to have this type of compressor close to where you are working. The racket generated when a shop compressor kicks on to refill the air tank may cause you to add unwanted images to your artwork, if not other areas as well.

Investigate your options before buying your air source. It is better to put your money in a superior airbrush and wait on purchasing the compressor of your desire, than to do the opposite. Your airbrush is your artist’s tool; the compressor is just a source of air. It is, of course, vital to the airbrushing process and in the long run, a consistent, good quality air source is vital.

What type of Paint do you use?

Almost any medium that can be thinned technically can be applied with an airbrush. The size of the nozzle opening dictates the thickness of the color that can be used. The smaller the nozzle and needle size, the finer the line achieved, but finer nozzles require thinner paint.

For many years the main airbrush mediums used were watercolor, gouache, ink and dye. Most of these products spray well poured directly from their jars. These paints dry by absorption, are excellent for spraying on paper for illustrations, and cause minimal clogging problems with the airbrush. Unfortunately they have to be protected from the elements.

Urethane solvent based paints are most often used for automotive applications, but body suits and commercial filtering masks must be worn to keep from breathing or absorbing the poisonous fumes.

Acrylic, water based colors have become the airbrush artists medium of choice due to their flexibility. Latex paint bonds with itself (cross-links), as well as to the work surface. Acrylic artist tube paints are made with large-particle latex and they cross-link and skin over quickly when exposed to air, which will easily clog an airbrush. Acrylic airbrush paints were developed to overcome this tendency by remaining fluid for a longer period of time. They dry quickly when sprayed, but do not actually cross-link of cure until they are exposed to heat. They will, in time, cure on their own for applications when the heating the surface would be detrimental. On most surfaces a heat gun or hair dryer will quickly cure the paint. On textiles turn the item inside out and press with a hot iron, or tumble dry on high for 30 minutes. These colors spray well and adhere to almost any surface to which it was applied. They and flexible after curing and wear well. Illustration airbrush colors usually do not require heat setting.

Water-based water-born acrylics are now making an impact in automotive applications as well. These acrylics use automotive quality pigments and develop a hard surface when cured. Acrylic automotive paint is now used both in manufacturing and in custom aftermarket automotive paint applications. This paint also adheres well and is excellent on exterior surfaces, or any surface requiring a hard finish. It is recommended that a urethane clear coat be used for automotive finishes; however acrylic clear coat is adequate for non-automotive applications. Research is being done to product an automotive grade acrylic clear coat to eliminate entirely the use of poisonous solvents and urethanes. Many custom automotive paint shops are producing award willing finishes due to this paints brilliance and depth of color.

The most popular auto paint remains oil based due to its tenacious adherence properties and smooth application, but for commercial applications the EPA regulations require a good spray booth, a body suit and a commercial respirator. The has been a lot of new water suspended oil paint introduced in the last few years that dramatically reduce air solvents. These seem to be a good compromise between water based acrylics and solvent based oil color.

Acrylic Airbrush Color Techniques

In airbrushing and general painting applications, it is recommended that you never thin acrylics more than 15% with water. Some of the modern art acrylic-wash paintings done in the 60’s and 70’s are now crazing due to the acrylic being over diluted with water. There are airbrush mediums and reducers designed for thinning color while maintaining its acrylic bond. Do not thin automotive acrylic with water. Only thin with the reducer.

It is best to purchase color especially formulated for airbrushing and airbrush paint should be the consistency of milk or no thicker than cream. Thicker color may be sprayed by increasing PSI, or air pressure. The ability to spray thicker colors is also determined by the size of the airbrush orifice and the type of airbrush used. As stated earlier, an external-mix single-action airbrush can spray the thickest medium and is often used for ceramic glazes, thick enamels, and heavy bodied paints, while an internal mix airbrush has the most artistic flexibility, but requires the medium to be thinner.

What Accessories and Tools do you need to begin Airbrushing?

The beginner can get by with 4 basic items to begin airbrushing. These are: an airbrush, a hose, an air source and paint. Below are some of the items you may wish to recommend to the beginner.

Airbrush Cleaner: New non-toxic low-odor cleaners do the best job of cleaning the airbrush, but glass cleaner (ammonia and water) works fine for light cleaning and spraying through an airbrush. It is recommended that the airbrush body itself not be soaked in cleaner, as some models contain rubber O-rings that may swell or shrink. Airbrush restorer or artists’ paintbrush restorer is excellent for dissolving dried paint inside the airbrush and it also rejuvenates rubber gaskets and seals.

Moisture Traps: These are available in-line, or the more efficient units can be attached to the compressor or to the airbrush holder and can be combined with a pressure regulator. Moisture condenses in the air hose as the air travels from the compressor to the airbrush. This may build up and be ejected through the nozzle, splattering on the artwork. A moisture trap works far more efficiently when it is placed in line, away from the compressor. This gives the air time to cool down and the moisture to be more easily separated from the air.

Dust Masks and Respirators: Although most airbrush paint is non-toxic, it is always advisable to wear a mask or use a spray booth. It keeps your nose hairs clean. When spraying solvent based paint the EPA requires a body suit, heavy dust chemical mask and a spray booth.

Frisket and Masking Material: Fine details requiring precise definition are achieved with the use of masking material. Frisket film is adhesive backed and is available as clear or matte. A sketch is made on the airbrush board or surface. The backing is removed and the film is applied to the prepared surface. The artist cuts out the area to be airbrushed first with an art knife, and these are removed. When the painted surface is dry, the artist replaces the sections removed previously, and the next areas are cut and removed for spraying. In this way extremely fine detail and fine edge definition are maintained.

Airbrush Templates: Templates and stencils are used to define hard edges when spraying free hand, or as a completed pattern. When airbrushing freehand, the artist can only achieve a soft edge definition without the use of a template. When airbrushing a face, the muscles and contours would be shaped with an airbrush freehand, while the outside facial edges and eyes would be defined with the use of a curved template. Professional airbrush artists make extensive use of templates, stencils and masks, as well as freehand work.

Artists Knives: A razor sharp artist’s knife is a must in airbrushing. This can be a standard fixed graphic artist’s knife, or a swivel blade for the more experienced. The main requirement is that the knife blade be extremely sharp.  When cutting masks and stencils you will think you are a klutz and become very frustrated if you do not have a very sharp knife. Knives are also used to scratch away color, and are great for detailing hair on airbrush portraits.

Erasers: Erasers are used to remove color or highlight. In illustration or general artwork an eraser is a great highlight tool. Instead of using white paint to add highlights, the artist removes the surface of the painting to expose the white surface beneath. This way, surrounding colors are not compromised. Electric erasers are great for highlighting airbrush work on canvas.

Scribing Tool: A rounded pointed tool used to scribe an image onto acetate to make a stencil. When the image is scored, the acetate is flexed and the scored image pops out.

Paint Brush: Used for adding details to an airbrush painting. Although most anything is possible with an airbrush, it is sometimes easier and quicker to add some details with a free hand artists brush.

Stencil Burner: Similar to a wood burner, but with a fine tip. Used for cutting stencils quickly in acetate and polyester film. Can also be used to identify your appliances!

How do you Clean an Airbrush?

The key to successful airbrushing is the proper maintenance of the airbrush. This, along with the use of proper paints, will allow you trouble free airbrushing.

At the end of the day remove the color cup or jar. Hold the brush upside down spray out remaining paint and swab out the color socket. Spray cleaner through the airbrush until the spray is clear. Remove the needle and wipe off any paint. On an internal mix keep the finger lever secured, as the needle holds it in. Check for accumulated color in the aircap and remove with a toothpick wrapped with cotton. Replace the needle. Spray water through the brush to remove excess cleaner. Clean paint cups, cap color bottles and rinse off cap assemblies.

On an internal-mix a more thorough cleaning is achieved by also back-flushing your airbrush. Attach a color jar containing about ¼ inch of cleaner. Cover the aircap with the tip of your finger and press down on the finger lever (also pull back lever on a double-action). This causes backpressure, which induces a bubble action inside the airbrush and container. This forces air back through the paint path, which flushes paint particles into the cleaner container, cleaning the fluid passages. Remove your finger from the tip and replace several times to maximize the back-flushing action.

It will be necessary to periodically disassemble the airbrush for a thorough cleaning and check of its components.

External Mix – Spray cleaner through the airbrush until clear. To clean clogged fluid passages use the wrenchto loosen the set screw and unscrew needle from tip. Gently pull back through ball-shaped support and remove tip. Clean parts carefully, using nothing harder than a toothpick. Soak needle and tip if necessary to remove dried paint. Apply a tiny dab of Vaseline to the color adjusting parts every couple of months to lubricate and prevent color build up.

Double Action / Internal Mix – To completely disassemble the airbrush first remove the handle. Loosen the locknut and remove the needle.  Remove the locknut and unscrew the needle-adjusting sleeve. Slide out the spring and remove the rocker assembly. Remove the finger lever assembly. Unscrew the aircap and aircap body and gently work the tip free. This is as far as you would generally need to go in disassembling the brush.

There are a few other things to note. Looking in the airbrush body from the rear you will notice a brass-packing nut, which the needle slides through. This nut holds in the packing washer.  If there is no noticeable drag on the needle by the packing, then tighten this brass nut. Some brushes use a rubber O- ring. Over a period of time the action of the needle will wear the packing and it must be replaced. A loose needle can cause sputtering if there is air leakage around the needle. To replace the packing, unscrew the nut, make a hook on the tip of an old needle, hook the packing and remove. Insert a needle partially into the airbrush and use it to thread the packing washer and brass nut back into place.

You may never need to disassemble the air valve assembly, but you should know its components. Remove the air valve nut using a small screwdriver. These components are small; so take care to work in a protected area. Slide out the valve spring, valve plunger and valve washer. If the washer does not come out with the valve plunger, use your hooked needle to remove it. Take care to replace these components in the proper order.

All parts, excluding the airbrush body can be soaked to remove dried paint. Do not soak the airbrush body in solvent as it contains the packing washer and air valve washer, which can swell or dry out. If you use airbrush restorer (Createx), it will dissolve the paint and rejuvenate the packing.

Reassemble Double Action Airbrush – Inspect the tip for damage. Replace tip and screw on the aircap body and aircap. Make sure to snug the aircap body with the wrench provided. If not snug, air will be sucked under the aircap body, which will cause bubbling in the paint jar or cause the airbrush to spit.

Looking down the shell assembly gently guide the finger lever assembly through the slot and into the opening for the air value. Do not push, but slightly wiggle the finger lever until the piston drops down into the hole. Press the finger lever a couple of times to make sure it is sitting properly on the air valve. While holding down the finger lever, replace the rocker assembly. Make sure that the small tab on the rocker assembly is seated behind the finger lever in the slot. Pull back on the finger lever to hold the rocker assembly in place. Thread the spring on the rocker assembly and screw in the needle-adjusting sleeve until desired tension on finger lever is achieved. Loosely screw on the locknut. While pressing down on the trigger, carefully slide in the needle, rotating if necessary, until the needle’s point is visible through the tip. Tighten the locknut and check for smooth trigger action. You should feel tension on the lever as you pull it back and it should spring-up if you depress and release it. Screw on the handle. This varies somewhat depending on the manufacturer of the airbrush.

Reassemble External Mix Airbrush – Reverse disassemble process.

What are the Problems / Corrections?

Using improper paint or the inadequate cleaning of the airbrush causes most problems with the airbrush. These are a few of the problems you may run into, their causes and solutions:

If the paint fails to spray when the finger lever is depressed, you may be using paint that is too thick. You could also have dried paint in your airbrush, which would require a complete disassembly and thorough cleaning. First check and see if you have a loose needle lock nut.

If your paint splatters or spits, check for a worn or damaged needle or tip. Your paint may be too thick or too heavy to flow properly, or the air hole in the color jar may be clogged. Paint oozing from the jar is also caused by the jar’s air hole being clogged

Moisture in air line will be ejected as a splatter. In areas of high humidity a moisture trap is essential.

An inability to achieve thin line is often caused by the paint being too thick, the air pressure too low, a damaged or dirty needle or nozzle, or a needle that is not seated properly in nozzle.

Spraying too close to the surface for the amount of paint being sprayed, or an improperly seated needle causes spider webbing.

Fuzzy lines are caused by a dirty head assembly, or a damaged needle or tip.

The air pressure being set too low causes grainy spray.

An irregular spray pattern is often caused by impurities in the paint or a dirty or damaged nozzle or needle.

To remove paint particles that have clogged an internal-mix airbrush, remove the handle. Grasp the needle adjusting sleeve and pull back. Press down on the lever to the blow clog out of the tip. If clogging continues to be a problem, thin or strain the paint you are using to remove impurities. The addition of a cut-through handle eliminates the need of removing it in performing this function.

If your paint bubbles or seeps from the jar, clean and tighten the head assembly.

If air is leaking around the air hose connection, snug up the nut with a wrench. The hose fitting has to be snug to seal properly. Often new users think their hoses are defective, when they have only failed to tighten the connection.

Some heavier bodied paints have the tendency to build up on the tip of the airbrush. Use a toothpick wrapped in cotton to gently clean the aircap. You may find it necessary to periodically remove the air cap and pinch the paint residue off the tip. Thin the paint if necessary to reduce this problem.

An uneven or sputtering emission of color can indicate an obstruction in the airline. An air leak, after the finger button has been released, indicates that foreign matter has worked into the air valve assembly or valve washer and damaged them. Clean the assembly, check the valve seat for nicks and replace the valve washer if necessary. To lessen the chance of picking up dirt in your air valve, always blow out a new or suspect airhose with a blast from your compressor before attaching it to your airbrush.

Purchasing your Airbrush

Make your own decisions after you try different units in different applications, if you have the opportunity. If you are unable to actually try individual brushes, and have no specific use requirement, purchase a good quality general use airbrush. Remember, in learning to airbrush, it is better to have a tool with which you will not become frustrated. An adequate airbrush, quality airbrush paint, and proper training mean all the difference. Read your instruction manual and practice the training exercises. Good Luck airbrushing.