Curriculum Plan for Practical Airbrush: Robert Woodbury , Instructor Metro Community College

Lesson 1: Equipment: Making it work

Basic information about the airbrush. how it is constructed, how to fix it, how to clean it, which one to buy, how to adapt it to your use.

Lesson 2: Putting the paint where you want it

Masking techniques and materials. Making it so some areas receive paint without harming the rest of the surface or image.

Lesson 3:  Materials: what to use, where and how

            What paints are appropriate for what surfaces and materials.

            Paints and their applications

Troubleshooting your airbrush

Robert Woodbury can be contacted at (780) 462-7469  

 

Lesson 1: Equipment, making it work

Airbrush:   a device for the controlled application of paint using compressed air.

Pigments have been sprayed using air pressure since ancient times. Handprints on the walls of caves by using clay pigments sprayed from the mouth using the hand as a stencil date back to millions of years ago. In renaissance times a small atomizer was constructed to two tubes of metal at right angles to each other then blown into to spray fixative or pigment.  This primitive airbrush is still used today.  The airbrush is a great tool for the artist, craftsperson or hobbyist to create effects that would be otherwise difficult or impossible.

All airbrushes work by the venturi effect, that is to say that a moving stream of air has less pressure than the surrounding still air and this drop in pressure draws the paint from the paint reservoir and atomizes or sprays it from the nozzle.  The paint must be thin enough to flow smoothly through the airbrush.  The air pressure must be set high enough to pull paint up but not so high as it cannot be controlled and blasts all the paint out in one burst.

  Some airbrushes allow the control of both pigment (or paint) and airflow.  Usually to control pigment flow involves the needle moving back to allow a larger area of paint to be exposed to the stream of air.  Airflow is usually controlled by a needle valve similar to those found in tire stems.  On the Iwata airbrush, pressing down releases more air, pulling back releases more pigment.  It requires some practice to control both airflow and pigment so that there is no spitting, spattering or over spray.  Getting closer to the work surface means using less pigment, moving faster means more pigment and airflow.  It is possible to cover large areas evenly or lay down thin, fine lines with practice.

Airbrushes that do not have adjustable airflow usually have a set and leave it adjustment.  Inexpensive airbrushes can be used for basic work where masks or stencils are involved and cannot be used for freehand illustration without considerable frustration.  If you don’t want to bother with changing paint flow or dispersion than an inexpensive airbrush may be right for you.

Choose your airbrush carefully with consideration for your future uses.  If you are interested in just stenciling and flat colour application, an inexpensive airbrush will do, but if you find that you are interested in or will be working on detailed freehand work, a more expensive airbrush will save you time and frustration.  A larger airbrush is usually needed where the paint is thicker as in automotive uses. A smaller airbrush is required for detailed freehand or close-up work. 

Some interesting effects can be achieved by misusing the airbrush…  too low a pressure can cause an interesting spatter to appear, this can actually be the desired effect and can take the place of the more random toothbrush spatter technique.   Too much paint in one place can cause droplets to form then move outward from the airbrush, a treelike or root like effect can be achieved this way.  Ink drops can be moved around with just air, creating a very organic effect. Spraying water onto watercolor or non waterproof ink on paper can give very interesting effects too.

 

Compressors:

To make an airbrush operate requires compressed air.  This air can come from a number of places; a compressor, a pressurized cylinder, an air reservoir tank or even a spare tire.

Small, noisy compressors can be useful where you just need to get the job done and don’t want to lug along a huge heavy compressor.  Any large compressor can be used for airbrushing, though most contractor compressors are overkill.  Airbrushing only requires 10-30 PSI (pounds per square inch) and less than 2 CFM (Cubic feet per minute) Most large compressors supply 5-14 CFM at 100 PSI.  Not only that they are head splittingly loud. 

It is not necessary to break the bank to get air pressure though.   A cylinder of compressed air (15$ at most art stores) can supply up to 2 hours of sporadic airbrushing.  A vehicle tire, still on the rim, can supply 20-30 minutes, and then be refilled from a cheap tire inflation pump.

The ultimate compressed air supply would be steady (no pulsing), dry air (no condensation or water build-up) and absolutely silent and weigh almost nothing (easily portable).  Any real compressed air system is usually an exercise in compromise.   There are distinct advantages to expensive compressors for the professional.  The smartjet compressor weighs less tan 10 pounds, can supply two airbrushes and is quiet.  It also stops operating when the airbrush stops.

Usually compressors have a regulator.  This device keeps the air pressure steady until it falls below the set level.  In order to use any compressor for airbrushing it should have a regulator.  If the compressor has a tank and shuts itself off when it reaches a set pressure, a second regulator, to bring the air pressure down to 10-30 psi is required.

The quietest compressors are oil compressors, these may look familiar, as they are the same compressors as are used in refrigerators, just modified to compress air instead of coolant.  The next best are the diaphragmatic compressors. These have a motor, which moves a diaphragm and reed valves to compress air.  The noisiest compressors are the cylinder compressors, similar in construction to an internal combustion engine; the cylinder pulls air in on the upstroke, compressing it on the down stroke.  These compressors generally require periodic oiling and are fine for short periods of time on the worksite, but would lead to headaches and eventual loss of sanity in a small studio. 

One enterprising artist used a garbage can with a garbage bag and water on top of it to create pressure; you need not be so experimental. Move up, as you need to. Often compressors can be purchased from a pawnshop for very little, then modified with an additional regulator.

Masking: putting the paint where you want it

Masking the work surface is a way of putting pigment or paint wherever you want it.  But it is more than that.  A mask is anything which will block paint or pigment from hitting the work surface.

There are three basic techniques of masking.  One is to create a reusable stencil with cut out areas on a piece of material that allow paint to be sprayed through it.  These stencils should be created from a material that will put up with repeated painting and not fall apart.

The other is to adhere a material to the surface and cut away areas to be painted.   This would be a frisket or film with balanced adhesive.  Balanced adhesive will not pull paint off the surface or leave adhesive on the surface being masked. Frisket or film are of various thicknesses, the thinner the better for normal painting work, thicker for sandblasting or sanding a surface.   

The third is a brush on frisket, normally latex or wax used as a resist against the paint. This is usually applied with a brush to areas to be protected.   Latex masking fluid contains a slight bluish tinge to make it visible and should be applied with a brush dipped in a soap or glycerine solution this solution will form a thin microscopic layer over the brush bristles and surface so that it may be easily removed later.   With a wax resist, it must be removed with an iron and newsprint.

Stencils can be cut from almost any material, from paper to thick rubber sheet, from steel to plastic and are incredibly powerful and versatile tools to use with the airbrush.

Common materials are acetate or stencil paper, which looks like manila folder paper and is essentially the same, but contains some oil to repel paint.  Acetate or thin plastic is great for repeated use since it doesn’t rip, or get soaked with paint.  When cutting a stencil it is important to cut out contiguous areas. That means all shapes must be connected with no floating bits. When using a stencil, always hold it closely to the surface where the airbrush is aimed to prevent overspray.  If you want a soft edge, you can hold the stencil away from the surface.

Frisket film is a thin plastic film that can be purchased at any art or drafting supply store, it is inexpensive and generally easy to apply.  If unavailable, clear or frosted MacTac may be used.  Turn down one corner of the frisket, attach it to the surface, then peel back the protective backing from underneath. Now starting at the middle of the piece of frisket, press it onto the material.  Work your way out from the center in sweeping motions.  If the material forms a fold or deep gulley, make an incision or cut and allow the material to bond to the surface around the cut or mask.  Always be careful not to cut the surface anywhere you will not be putting paint.

Fluid masking is sometimes difficult to use and expensive, but is an excellent solution for very curvy surfaces.  Use a clean brush dipped in glycerine, or dish soap mixed 1/1 with water to maintain a film on the surface of the masking fluid. This will serve as a release from textured surfaces and keep it from clogging the brush.  Always store masking fluid away from heat or extreme cold as it will congeal.  Cleaning up masking fluid may be done with a plastic eraser or a ball of rubber cement.   Thin your masking fluid with ammonia and water.  The ammonia will keep the latex liquid and can also be used to clean up.

Lesson 3: Materials

There are many materials that you can use with an airbrush; Watercolour, Oilpaint, Acrylic, Enamels(oil or acrylic), Dyes, Inks, Solvents, Gouache or Plakka, coatings, varnishes and raw pigments.  The common denominator is viscosity or flow.  Any substance which is liquid and can be thinned down to a milk consistency can be put through an airbrush.

Dyes: fluid dyes can be used on paper, cloth, or any primed surface.  Priming is just painting it with either Gesso or latex primer.  Fluid dyes sometimes need to be set up with heat before washing and sometimes the fabric needs to be treated with a mordant or mild acid to give it tooth so it can accept the dye.

Inks: The very first ink was just ground charcoal and water, later the shells of insects or shellac were added to give it staying power. All inks can be put through an airbrush undiluted, but care must be taken to clean the airbrush after using shellac containing inks as they will clog the airbrush over time and the shellacs are not water soluble and thus not easily cleaned out once dry.

Gouache: The first opaque paints were just finely ground chalk and glycerine these are called gouaches and are great for illustration wrk.  Gouache is normally provided in a tube and must be thinned with water to allow it to be sprayed.  If necessary more glycerine may be added to allow it to bind to the paper better.

Watercolours:  many watercolours are available premixed with water for spraying. If mixing from solid blocks of watercolour or tubes you should pass the mixed paint through a screen or silk handkerchief (old one…) to filter out clogging chunks of paint.

Acrylics:  Acrylic paint is composed of tiny spheres of plastic and colour floating in a suspension of water, when the water drys up the little plastic spheres join up to form plastic. The pigments in this paint can be organic like quinacridone or inorganic like iron oxide, enamel or earth.  If you can find the colour and opacity you want in liquid acrylics or acrylic inks that is preferable since it only has to be thinned a little.  If you are thinning acrylics from the jar or tube, always add some airbrush medium or acrylic binder to improve bonding, otherwise the paint will just be little dust of pigment with nothing to glue it to the surface.  Acrylics thin with water and will clog your airbrush quickly if left to dry. They are waterproof and versatile, can be used on cloth, glass, metal, paper, walls, wood… well just about anything but over oilpaint.  Oil and Water don’t mix unless you use soap.

Oil Paints: Thinned with turpentine or odourless thinner oilpaint will flow through the airbrush with ease.  This can be very usefull when touching up an oilpainting. When the airbrush was first used to tint photographs, oilpaints were what was used.

Surface preparations: most shiny surfaces must be sanded or sandblasted to create a rough surface that will hold paint.  There are primers available for most surfaces that will accept almost any paint.  Spray primers for metals and latex primers for everything else.

To avoid frustration:

Always work in a well-ventilated space when spraying solvents. 

Your workspace should be clean and not dusty. 

Always read the labels on paints. 

Clean your airbrush after every use

Troubleshooting your airbrush:

 

No Air comes out:

  1. Ensure the compressor is operating and connected by hose to the airbrush.

  2. Check air hoses for kinks

  3. Check the nozzle for severe clogging, if there is air coming out with the nozzle guard removed, then it is definitely a clog.  

  4. Clean out the nozzle with airbrush cleaner and a pipe cleaner.

  5. Check air valve in airbrush to ensure it is working.  

Spatter: 

  1.  Check pressure from compressor, low pressure will cause spatter.  If there is a lot of condensation in the tank from use, it must be drained.

  2. Check nozzle for clogs.

  3. Check for paint thickness (if too thick then thin paint with water or solvent)

  4. Check paint cup for clogs

  5. Check paint jar for plugged air hole

 

Too much paint comes out:

  1.    Reduce air pressure

  2.   check needle to ensure it is snug in the nozzle. Loosen needle chuck and push in needle NOT TOO HARD; you can break the orifice!

  3.  Check setscrew to ensure it is not forcing open state.

  4.   Check that nozzle Is tight

No Paint comes out:

  1.   If no air pressure: see troubleshooting step 1

  2.  Check for simple clog, flick airbrush lever and spray on scrap.

  3.  Check for clog in cup or jar

  4.  check for clog in air hole of jar

  5. Check for clog in nozzle:

  6. Carefully loosen nozzle.  If there is spray, clog is in nozzle or tip of needle. 

Backfiring:  air bubbles in cup or jar:

  1.   Loosen nozzle, if this stops problem, clean nozzle and orifice.

  2.   Check tip for large build-up of paint

  3.  Check for low pressure.

Miscellaneous problems

  1. Pulsing, spots: lower pressure, bad regulation

  2. Spidering: too much ink

  3. Puffing: not enough ink flow

  4. Spitting: paint too thick, low pressure, clogging

Thorough cleaning solves many problems,

  1. Spray airbrush cleaner through airbrush

  2. Rinse out cup or jar

  3. Take off nozzle and soak in airbrush cleaner

  4. if clog persists: Remove needle and CAREFULLY clean tip that seals to nozzle and orifice.
    Try not to bend the needle this will cause off center spray.

 

1