Airbrush Tips (Vol.1)
BEGINNING AIRBRUSH TIPS - VOLUME I "GETTING STARTED"
The Airbrush is an incredibly versatile and useful tool. However, getting started can be a daunting task. This Information Sheet aids the beginning airbrush student.
First, as simple as it sounds, ask yourself ‘What’s the main reason I want an airbrush?’ How you answer this question should help you learn what airbrushes are best suited for your immediate needs.
After you have practiced using the airbrush, its abilities and limitations emerge, you may want to purchase another airbrush or spray gun if it makes sense. This approach saves money and time, and reduces the chance of buying the wrong equipment. Many airbrushes sitting in closets or on shelves aren"t used simply because they were not what the artist needed at the time.
Purchasing an Airbrush
There are over a dozen airbrush manufacturers, each with several airbrushes for the most exacting applications. Some manufacturers have in excess of 40 models from which to choose. As overwhelming as this may be, keeping focused on one"s individual criteria narrows the choices.
Two trade magazines available to the American market, Airbrush Action® and The Airbrush Step-By-Step®, have frequent product reviews and buyer"s guides. Also obtain artist materials catalogs and compare prices with local art stores.
Seek Professional Advice
The best source for a beginner can be a seasoned “vet” who can offer insight on how to get started and what equipment they prefer. After all, they too were beginners at one time, and know well what one goes through making these decisions. Personal acquaintances, art teachers, and local professionals will usually give free advice and may offer beginning airbrush lessons. Airbrushing magazines have many articles and artist reviews that cite what equipment they prefer. Keep in mind that these professionals have very specific requirements and typically use several airbrushes to meet all of their spraying needs.
HOW AN AIRBRUSH WORKS
The way an airbrush works is actually quite simple. Air and paint meet and the air forces the paint to break apart into small droplets. This process is referred to as “atomization”. Atomization controls the size of the paint particles.
In a garden hose slightly opened up, water passes through the nozzle, and results in a fine mist because a small amount of flowing water is under a high degree of pressure. The same nozzle at the same water pressure turned wide open allows the water to flow freely and the pressure propels the water a greater distance because it is a steady stream instead of being atomized into fine droplets.
In an airbrush, instead of water pressure dictating the atomization, it is accomplished with air pressure. The paint and air meet right in front of a tapered point known as the needle.
The droplet size is determined by the airbrush needle size, the air pressure setting on the compressor (measured in pounds per square inch, or “p.s.i) and the fluidity of the paint. Getting this combination under control can be the most difficult aspect of spraying.
The Airbrush Needle and Nozzle
All airbrushes work on the same principle; air and paint meet at an exact point in space. At that point in space a tapered "needle" projects the combined air and paint outward. Airbrush head assemblies have amazing baffling systems funneling air around the needle and atomizing the paint evenly. Instead of one air stream there are several and that helps to atomize the paint into consistently sized droplets.
Fine line spraying requires very delicate needles tapered to a precise point. The finest detail airbrushes have a nozzle opening size of .18mm. Large commercial spray guns, such as those used for automotive painting have blunt needles that do not have much of a taper. They are made to fit into large nozzles (usually from 1.0mm to 2.3mm) meant to deliver higher volumes of paint. Larger nozzles can spray thicker paint resulting in faster coverage.
The nozzle is the part of the airbrush head assembly in which the needle rests. It is tapered exactly the same as the needle it holds. On a single-action airbrush, when the screw is twisted, it widens the space between the needle and nozzle by unscrewing the nozzle cone. In a double-action airbrush, when the trigger is pulled back, it moves the needle away from the stationary nozzle. The farther back the needle moves, the larger the space between the needle and nozzle.
NOTE: Airbrushes are devices that rely on proper care and cleaning. Always spray plenty of water to flush out paints between colors and before and after spraying. This reduces the frequency of having to perform complete airbrush breakdowns and cleaning out dried paint inside the airbrush.
Single-Action vs. Double-Action Airbrushes
Single-action is similar to an aerosol can of spray paint. The finger presses the cap (also called a finger button) and it begins to spray. The amount of paint flowing out is controlled by twisting a knob or screw located near the tip. This type of airbrush is also referred to as an "external-mix," because the air and paint mix in front of the needle. There are few moving parts requiring regular cleaning, making it an easy airbrush use and maintain.
The single-action airbrush does not have the precise control offered by a double-action; however, a single action is a great beginner"s brush that will always have uses no matter how advanced an artist becomes. Smooth gradations are easily accomplished, and for many artists, this will be the only airbrush they will ever need.
A double-action airbrush offers much greater control and is essential when producing fine lines and thick-thin strokes (the classic "dagger stroke"). These are also known as "internal-mix" airbrushes because the air and paint mix inside the nozzle. The double-action airbrush has two trigger movements. As with the single-action, airflow is controlled by depressing the button (resting on top of the “finger lever”. The amount of paint however is controlled by pulling the finger lever back instead of twisting a front knob. The farther the lever is pulled back, the more paint comes out.
Precise control and line variation is achievable with this kind of airbrush. Fine lines and lettering is much easier and experienced, "freehand" (painting without the aid of masking materials) airbrushers can control a double-action to produce photo-realistic artwork.
Siphon-feed Vs. Gravity-feed Vs. Side-feed Airbrushes
How the color cup and/or bottle are attached to the airbrush body is different for various models of airbrushes. This feature controls the amount of paint loaded up before having to refill. It also plays a role in the comfort and use. For example, a large color cup on the top of the airbrush gets in the way of the line of sight when spraying and can feel off balanced to some. A small cup can be annoying when you have to constantly refill it during a large painting project.
Siphon-feed means that the color-cup attaches from underneath the body of the airbrush. Air suction pulls the paint from the cup to the nozzle area, where it comes in contact with the air. This type of airbrush is useful when spraying for extended periods of time because the color-cup (typically 1/4 ounce capacity) can be taken off to behave more like a gravity feed airbrush and a bottle can be attached for larger volumes of paint.
Gravity-feed essentially means that the color-cup is on top of the airbrush body. Most models have an immovable color-cup. Although larger airbrush models can have paint reservoirs of 2 ounces, gravity-fed airbrushes are made for detail, where small amounts of paint are applied at one time. Because the paint is in an open color-cup, some models offer a separate cap to keep paint from spilling. They have a tiny hole in the center of the cap to prevent a vacuum from developing. It is essential that this hole be open to maintain proper paint flow. Siphon-feed bottles also have this hole on the cup-cap for the same purpose.
Side-feed color cups attach on either side of the airbrush rather than on top (gravity) or bottom (siphon). This feature allows the artist to choose which side they prefer to have the cup to suit their holding style. In fact, these airbrushes can have a gravity feed style color cup or a siphon feed bottle attached as desired.
Mixing Paint to a Sprayable Consistency
Aside from proper technique, good spraying is a result of the right combination of spray equipment, proper air pressure and adequately thinned paint. When one starts an airbrush project, all three aspects can be adjusted and refined before and during spraying. If the appropriate airbrush has been selected, then the paint needs to be at the proper consistency for spraying.
A typical airbrush spray paints between 40 and 80 cPs. “cPs” is shorthand for centipoise and is used to measure paint’s viscosity. Using a detail airbrush for precision work means working with low viscosity paint and low pressure settings. Larger areas require bigger airbrushes and higher pressure settings. Spraying large area with too thin of a paint results in more paint in the air instead of on the art surface. If the paint is too thick, then it doesn’t flow through the airbrush properly resulting in spatter, grainy paint patterns if it sprays at all.
The paint not only needs to be the right viscosity, but smooth flowing within the airbrush during spraying. This combination of thickness and flow is called consistency. Thinning with water can be done if the paint has the other key properties. If not, then the use of GOLDEN Airbrush Medium - or High Flow Medium- is required. These products a thin but also add retarders and flow improvers to transform the acrylic paint into airbrush paint. Basically, the paint needs to flow freely and readily. With experience, mixing paints by the feel alone is possible. Until then, stick to the recipes suggested for each product. Some products will be ready to spray right from the bottle, such as the GOLDEN High Flow Acrylics. Some colors may need to be altered depending on the equipment and application but beginning airbrush artists can greatly benefit from product ready to spray.
Adjusting Air Pressure
Equipment manuals usually provide initial setting air pressure based upon the intended use. Some have more details for the kinds of paints and surfaces. These are starting points and it is expected adjustments are likely needed. If the paint seems like it’s the right consistency, and the equipment is worked well during startup (more on this later), then try increasing the air pressure a little and see if the spraying quality improves.
What is an "Air Source"?
An airbrush"s air source is where the pressurized air (that propels the paint) comes from. Aerosol cans, CO2 tanks, air regulators, air compressors, air tanks, even tire innertubes can be considered to be air sources.
A reliable air source can be a bigger investment than the airbrush. If an artist is just exploring the possibilities of an airbrush with the least amount of investment, rent or borrow the air source.
Selecting the Proper Air Source
The type of needed air source is dictated by three factors:
- the type of spray equipment
- the kinds of spraying
- the amount of work
Each air source has its own pros and cons. Some require constant refilling. Some are loud. Some are just simply unable to deliver the level of performance required for the work you want to achieve. Generally speaking, small projects with short spraying times and low viscosity paints can be accomplished with a wider range of air sources. Bigger projects where there is a lot of spraying involved (or a lot of precise detail work), require a source of constant air pressure for long periods of time require compressors or CO2 tanks. Other considerations - cost, space, noise constraints, and availability of electrical power - may force one to choose one source over another.
Below is a Quick Reference Chart showing the pro"s and Con"s of the more popular air sources
|Air Source Type||Positive Attributes||Negative Attributes|
|Compressed Aerosol Can||low cost, constant air pressure, silent, very portable||low pressure, runs out fast!|
|Tire Inner Tube||low cost, refillable, constant air pressure, silent, portable||low pressure, runs out fast, pressure quickly lowers|
|Air Tank||low cost, refillable, very portable, various sizes, pressure regulator||medium pressure, runs out fast, pressure quickly lowers|
|Air Regulator/Compressor (without Air Holding Tank)||inexpensive, long life, small size||constantly runs, gets hot, low pressure, pressure drops of while spraying, noisy, useselectricity, pulsating air flow|
|Oil Lube Air Compressor||moderate pricing, reservoir tank, higher pressures, automatic shut-off, built in regulator,constant air||noisy, needs frequent oiling, oil can get into airline, uses electricity, tank needs frequent"bleeding" of moisture|
|Oil - less Air Compressor||moderate pricing, reservoir tank, higher pressures, automatic shut-off, constant air, builtin regulator||noisy, uses electricity, tank needs frequent "bleeding" of moisture|
|Silent "Pancake" Compressor||"silent", automatic shut-off, constant air, built in regulator, compact size||expensive, uses electricity, needs frequent "bleeding" of moisture|
|CO2 Tank||truly silent, built in regulator, moderate pricing and/or rentable, no electricity needed,portable, long lasting, moisture-less air source||needs refilling, all connections must be secure to avoid freezing up, moderate danger ofcompressed inert gas|
How to Know Which Type of Paint to Buy
Golden Artist Colors produces several lines of acrylic paints that can be sprayed. However, with the exception of High Flow Acrylics, they all require thinning with a medium and/or water to reduce viscosity. Rather than looking at this as an inconvenience, this allows for absolute control of their paints. Modify a base paint to suit your immediate needs.
Of the wide array of GOLDEN paint lines, the Fluid Acrylics and the High Flow Acrylics are the best products to use through an airbrush. Other paints can be used of course, but their thickness means higher dilution with water and medium, impacting pigment load.
Thinning Fluids Acrylics for spraying is as simple as mixing 1 part paint to 1 part Airbrush Medium. This mix should spray well at around 40-50p.s.i, and in airbrushes of 2.5mm or larger. However, each paint has its own unique formula and some may require additional thinning with water. More Airbrush Medium can also be used instead of water but it can slow the drying time down of the paints if over-added. This mixture may be used for most airbrushing applications.
Thicker paints like Heavy Body Acrylics should be first thinned by adding water and mixing carefully until a pourable consistency is achieved. At that point, add 1:1 Airbrush Medium to the original mixture.
If the paint is going to be used transparently, the GOLDEN High Flow Medium can be a better choice. Start at 5 parts High Flow Medium to 1 part paint and adjust transparency as needed.
On launderable garments, exchange the Airbrush Medium or High Flow Medium for GAC 900, a heat-set fabric medium. This provides a soft hand and improves launderability.
As with learning how to use any tool or try a new artist technique, learning how to airbrush takes time and patience. Take the time to research equipment and techniques, and practice as much as possible on cardboard, paper or whatever test pieces you can work on. See also “Beginning Airbrush Tips Volume II.”
The above information is based on research and testing done by Golden Artist Colors, Inc., and is provided as a basis for understanding the potential uses of the products mentioned. Due to the numerous variables in methods, materials and conditions of producing art, Golden Artist Colors, Inc. cannot be sure the product will be right for you. Therefore, we urge product users to test each application to ensure all individual project requirements are met. While we believe the above information is accurate, WE MAKE NO EXPRESS OR IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, and we shall in no event be liable for any damages (indirect, consequential, or otherwise) that may occur as a result of a product application.