Bottom feed, gravity feed, and side feed — what's the difference?
The method for feeding paint into the airbrush affects how it comes out.
Bottom feed airbrushes (also called siphon feed) create an internal siphon that draws in color from a jar attached to the underside of the airbrush. They enable artists to cover large areas quickly, and it's easy and fast to change colors just by switching jars. Because the jar is below the airbrush, you have a clear, unobstructed view of your work. However, to properly use a bottom feed airbrush, your compressor must be set to at least 18 PSI, resulting in less control and more overspray.
Gravity feed airbrushes use the force of gravity to draw paint down into the airbrush through a top-mounted color cup. They're excellent for fine detail work and the most artistic applications because they produce the finest dot spray pattern. You can set your compressor as low as 8 PSI with a gravity feed airbrush, which allows for greater control over gradations, shadows, and other effects. However, the smaller color cup isn't good for mass coverage, and the position of the color cup may block your view.
Side feed airbrushes deliver paint to the airbrush through a side-mounted color cup that can be adjusted for left- or right-handed users. On the side, the color cup is out of your sightline, and the cup can be swiveled to allow you to spray straight down on a tabletop or straight up on a ceiling. One disadvantage is that the compressor must be set to at least 12 PSI for the airbrush to work properly, so some experience is required to obtain precise control at the higher pressure.
How is a double-action airbrush different?
A double-action airbrush delivers paint with two steps — you push down on the trigger for air, and then pull back for paint. This enables you to vary the spray pattern while in the process of painting. With more precision and control, you can employ artistic color gradations, shading effects, and lines of various widths. This type of versatility isn't necessary for every task, but for artwork it's great.
Double-action (or dual-action) airbrushes are internal-mix types. The mixing of paint and air occurs inside the airbrush head assembly, resulting in a soft, fine dot spray pattern that's preferred for almost all precision art and design applications.
Is it necessary to use a pressure regulator?
It's not absolutely necessary, but once you use one, you'll never want to work without a regulator again. A pressure regulator and gauge combination controls air output to the airbrush and becomes a necessity when your techniques and/or paint viscosity require you to control the airflow. Having a compressor that gives you a wide range of pressure to regulate allows you to experiment with a wide range of paints and techniques. For a selection of pressure regulators, visit our Compressors and Accessories page.
What can an airbrush spray?
Any liquid that can be thinned to the consistency of milk can be sprayed through an airbrush. However, if some liquids are thinned too much, they won't perform properly, so some judgment should be used in selecting the right airbrush for a particular job.
Generally, thick liquids such as textile paints or ceramic glazes should be thinned cautiously, and a single-action airbrush should be used. Thicker materials should be sprayed with higher pressure than thinner colors. If the liquid is thin (dyes, inks, etc.) or if it thins well, a double-action airbrush and/or lower pressure may be used.
What is a single-action airbrush?
Single action is the simplest type of airbrush to operate. When the trigger is pushed down, color is sprayed in a single action at a preset rate. To change the rate, simply stop spraying for a moment and turn the color valve slightly. Commonly used for hobby, craft, stenciling, and mural work, single-action airbrushes make it easy to apply even coats of color but make it more difficult to execute any variations in shade, tone, or line width. These airbrushes tend to be less expensive than double-action models.
Most single-action airbrushes are external-mix types. They mix the air and the color outside the airbrush head assembly and are therefore less likely to clog if heavier materials are sprayed. External-mix airbrushes also have a coarser dot spray pattern that is mostly recommended for high-volume coverage. Acrylics, ceramic glazes, and auto paint (lacquers and enamels) are commonly sprayed with a single-action brush.
What is the difference between a hot press and a cold press surface?
Hot press board is smoother, and is generally slightly more expensive for a given size and weight. Artists who work with airbrush, markers, or pen-and-ink often favor a hot press surface. Hot press boards produce sharper and finer lines. Graphic design applications also tend to favor a hot-press surface, especially when adhesive wax, adhesive film, rubber cement, or transfer lettering is used. Hot press board scans better. Sharper detail can be reproduced from its smooth surface.
Cold press board is slightly textured, and is usually favored when a brush is used, as for watercolor, gouache, acrylic, and tempera. Artists who work in a drawing medium that requires some "tooth" to the surface, such as charcoal, crayon, or pastel, also tend to prefer cold press. Calligraphers and graphite and colored pencil artists choose either surface, depending on personal preference.
Which airbrush should I buy?
Will I need a moisture trap?
Yes. A moisture trap attaches directly to your compressor and effectively reduces the amount of moisture in your air line. This is particularly important in warm and/or humid conditions. Moisture can also accumulate in your airbrush hose overnight. Spraying air through the airbrush for a few minutes before you start working will clear condensation from the line. For a selection of moisture traps and other airbrush supplies, visit our Compressors and Accessories page.