Delaware Valley Scale Modeler’s Seminar:
Airbrushing 101
By Tony Wootson
Friday, February 6, 2009
Do you own an airbrush? If so, do you use it regularly? Maybe you own one but have yet to get up the nerve to use it. Or, perhaps you own one, but you’re not quite satisfied with your results. Or, possibly you don’t have one, but have contemplated purchasing one. (First though, you'd like to learn how to use it).
If any of these statements describe you – (or even if they don’t) - then this article should be helpful.
I’ve been using an airbrush in my modeling for quite some time now, (probably 20 years). Even though cleaning it out when I’m finished is still a pain, I’ve discovered a way to minimize this unpleasant chore, and as a result, maximize my airbrush’s punch.
In addition, the fine control over the paint and the potential for a splendid paint finish makes me wonder how I ever got by without airbrushing before. (Actually, I do remember: I often had to strip and repaint my models because of various problems I ran into when using canned spray paints; in addition, I often ran into problems when painting with a paintbrush by hand).
Different brands of airbrushes
Some of the old, traditional airbrushes that have been on the market (forever it seems) are Badger and Paasche. Some newcomers to the field are Testors’ Aztek and Iwata.
Main characteristics of airbrushes – Internal versus External and Single Action versus Dual Action
In general, there are two different characteristics that all airbrushes have.
The first is that they can be either an “Internal mix” or “External mix” type. This terminology describes the mixture of the paint with compressed air that is traveling from its source – (whatever it is) – through the body of the airbrush.
As the descriptions indicate, the Internal Mix airbrush is designed to mix the air and paint internally, inside the body of the airbrush. What shoots out is a mixture of air and paint.
With an External Mix airbrush, both the paint and air meet at the tip of the airbrush's nozzle.
As is probably obvious, an Internal Mix airbrush gives you better control over paint than an External Mix one does. In addition, the Internal Mix airbrush allows for a more precise application of the paint.
The second characteristic of an airbrush is whether it is a Single Action or Dual Action type. This characteristic describes the function of the button that is pressed down to start painting, (along with a knob that may be found on the airbrush).
With both a Single and Dual Action airbrush, by pushing the button down you start the air flowing through the body of the airbrush. The difference is that with a Dual Action airbrush, you pull back on this button to increase the paint flow, while with a Single Action airbrush, you must turn a knob (located somewhere on the body of the airbrush) to increase or decrease the paint flow.
(Ok, that touches base on the airbrush itself. Now, how about the air sources?)
Air Sources
(Disposable) Air Propellant Cans
I previously mentioned that you need an air source to supply compressed air to your airbrush. There are a number of options that exist here. One is a can of compressed air. Badger, Paasche and Testors all produce them.
Advantages
An advantage of using a can of compressed air is its low cost. These cans generally run anywhere from $10 to $12.
A second advantage is that they are quiet to use.
Disadvantages
Unfortunately, there are numerous disadvantages. The first is the limited use. You’re not going to get a whole lot of air out of these cans, and you very well may end up using two or three cans to complete the paint job on your model. With this, the relatively cheap price of individual cans can quickly add up.
Next, you have very little control over your air pressure. The air initially comes out full force, until it starts dissipating, at which point your air pressure (naturally) will decrease.
Another thing that I’ve noticed when using a can of propellant air is that the can (along with probably the air) tends to get very cold. (Ice had formed on the outside of the can around the attachment that I had once used).
Air Compressors
For the modeler who is going to use an airbrush for the long haul, this is a better source of air than the propellant can.
There are many different manufacturers of Air Compressors, with different models having different features.
Advantages
Advantages are you now have a practically unlimited source of air that comes out at a constant rate. (Even though the motors on most compressors are only guaranteed for a limited number of hours, I've personally gotten around 20 years of use out of my Badger 180-1 Compressor, (which, despite the occasional crash down to the floor, is just now appearing to loose some of its power).
A second advantage is that with the addition of an air regulator, the air pressure can be controlled.
A third advantage is the quietness of some of the compressors. (You may have to shop around to locate one that runs quietly, though).
Disadvantages
A disadvantage is the price of this modeling tool. Traditional “Hobby” compressors generally run $150.00, up. I was able to locate several VERY reasonably priced compressors at the Home Depot Store. There were two models manufactured by Campbell Hausfeld, which ran $79 and $99.
A second disadvantage has previously been listed as an advantage. Some compressors make a good deal of noise. (Again, you should shop around for one that runs quietly).
A third is a somewhat minor attribute. However, it still exists. Since a compressor runs off of electricity, this ultimately will add a bit to the overall expense of painting a model.
Air Tanks
These are just large, metal tanks that are filled with compressed air.
Advantages
The prices of these can vary greatly. However, some very reasonable options may be available here. For example, it may be possible to obtain an old scuba tank to use. With the fitting of an air regulator, you’ll be ready to go.
In general, you can probably obtain an air tank for less than the price of an air compressor.
Another advantage is that air tanks are very, very quiet.
A third advantage is that you can paint a good number of models before having to refill the tank.
Finally, since it doesn't use electricity, you won't be adding to your electric bill with its use.
Disadvantages
A disadvantage of using an air tank is the routine expense associated with refilling it. Ultimately, it will run out of air. This fee probably will not be all that high, though, once you find a location that can fill it up.
A potential disadvantage is that air tanks tend to be large and bulky. Also, they can be pretty heavy, which may become a factor with the regular transport that the tank will go through, with it's refilling.
Air Compressor & Tank Combination
Combined air compressors and air tanks also exist. They can be obtained from a variety of sources, like Sears, home improvement stores (like Home Depot again) and some hardware stores.
Advantages
This can be viewed as the “best of both worlds.” Because the compressor runs, filling up the tank (which is the primary source of the air), these tend to be quieter than air compressors.
In addition, since your compressor is attached to your air tank, the need (along with the associated expense) of having to periodically refill the tank has been eliminated.
Another advantage is that since your compressor is not continuously running while you're painting, you are going to be using less electricity than with a regular air compressor.
Disadvantages
Well, there's not much here. You can purchase an air compressor/air tank combination for around the same price as some air compressors. Actually, the price is often cheaper, (probably since they aren't being sold as "modeling hobby" products alone).
The size may be a bit of a disadvantage, since most of these are larger than the straight air compressor type.
However, they also tend to take up less space than an air tank.
(That takes care of the airbrush's air source. How about the paints and thinners?)
Paints & Thinners – (acrylics, enamels and lacquers, Ohh My!)
Ok, now that I’ve dispensed with the air sources, I can move onto paints and thinners. You can use all sorts of “regular” paints in your airbrush. These include acrylic paints, enamel paints and lacquer paints. I’ve even heard of folks who want an exact color match - (that may only be available in a can of spray paint) - spray the canned paint into a small container, thin it down with some thinner and airbrush it on.
In addition, there are other guys whom I know of who have used women’s nail polish, mixing it in with lacquer thinner and airbrushing it on. – (Women’s nail polish is a lacquer paint).
Nowwww, folks may look at you kind of strange at the checkout counter as you pay for your “unique” model paints. However, the numerous, different types of vibrant colors available from this source make a bit of potential uncomfortableness worth it.
Generally, regardless of the type of paint that you use, you’re going to have to thin it down in order to get it to flow smoothly through your airbrush. Otherwise, it’ll be too thick and won’t come out smoothly, (but will splatter and very well may not come out at all).
An exception to this rule is Testors’ Model Masters (M. M.) Metalizer Paints, (which are composed of small, metallic flakes floating around in a diluted lacquer medium). In addition, Alclad II paints, (that are also diluted, lacquer based metallic paints) don’t need to be thinned down before using.
General rule for thinning paints
The rule of thumb here is to use the thinner that’s the same type as the paint. However, as is the case with just about everything in life, there are exceptions here as well.
You can mix “hot” thinners in with enamel paints. These include Lacquer and Xylol (or Xylene) thinners. Be veeerrrrrry careful with them, though. Use them in a well-ventilated area. Also, you should use them while wearing a respirator.
Both thinners are very powerful and can do your body BAD if breathed in. The Xylol (Xylene) is actually listed as a nerve agent.
A reason these potent thinners are sometimes used by modelers is because of their rapid curing time. The paint will cure very quickly (in a matter of seconds or minutes), allowing multiple colors of paint to be applied onto your model in one building session.
Another exception to the “thin the paint with the same type of thinner” rule is with acrylic paints.
With Polly-Scale acrylic paints, you can cut them with regular ole' windshield wiper fluid. (When you get the chance, compare a gallon of the blue-tinted windshield wiper fluid with Polly-Scale's "standard" thinner).
With the Windshield Wiper Fluid, you get a WHOLE lot more liquid at a fraction of the price of the more expensive,
name brand thinner.
I've also heard of folks successfully thinning other types of acrylic paints with a combination water, alcohol and a drop or two of liquid dish detergent. This dish detergent helps break up the surface tension of the water, that otherwise might cause your acrylic paint to bead up on the surface of your model.
(Onto airbrush accessories)
Miscellaneous airbrush accessories
There are several additional items you might need to attach to your airbrush.
An Air Regulator
I briefly mentioned an air regulator earlier. This is a device that allows you to decrease the air pressure that's coming from your compressor or tank. Since an unregulated air source is generally too powerful, this tool is very helpful in giving you better control over your airflow.
A Moisture Trap
A moister trap does as it sounds. If you are airbrushing on a humid day, it's possible for some of the humidity to accumulate within your airline in the form of water droplets. When they make their way towards and into your airbrush, the results are quite unpleasant. Your paint will just stop flowing or may oscillate, until the water finally comes out, mixing in with your paint and splattering onto your otherwise excellent paint finish.
The moisture trap can be either a plastic or metal cylinder. It's inserted into your airline, (that's coming from your compressor), with your air line cut in two and the moisture trap attached in between.
Both the moisture trap and the air regulator can be purchased from Sears and Home Improvement Centers. The can also be purchased from specialty - (here's that word again) - "hobby shops." Also, I'm pretty sure Squadron Mail Order carries them as well.
(Ok, I've discussed airbrushes, air sources, paints & thinners and miscellaneous items that you can attach to your airbrush - It's time to get to the actual airbrushing!)
Time to airbrush -Three variables to master
There are really only three things that you must master in order to get good results with your airbrush. They are:
Your paint to thinner ratio
Your air pressure and
The distance the nozzle or tip of your airbrush is to your model
For the first factor, I generally airbrush with Testors’ Model Master (M.M.) enamel paints, (although I’ve used Tamiya acrylics, M.M. lacquers and Floquil lacquers as well). I mix my M.M. paints at somewhere between 1/3 to 1/4 of thinner to 2/3 to 3/4 of paint. Also, I tend to stick with the M.M. name brand thinner.
For the second and third factors, they are both related. In general, the lower your air pressure, the closer you can get the tip of your airbrush to your model, without having the paint “pushed” all over the surface.
If you turn your air pressure down and pull your airbrush away from your model’s surface, you will probably end up with a grainy paint finish. Or, the paint may not even reach your model at all. (With the grainy paint finish, what's happening is your paint is drying just as it reaches your model's surface).
Conversely, if you increase your air pressure and pull your airbrush away from your model, you're going to get more of a full-paint coverage, as opposed to airbrushing small areas on your model, (like with the camouflage paint scheme on an aircraft or armor piece).
If you are too close with your increased air pressure, you will loose control over the paint flow and the airbrush will act just like a can of spray paint that's too close to the item that's being painted: the paint will be blown forcefully and pool on your model.
I usually turn my air pressure WAAAY down, (to between 10 to 5 pounds per square inch). For the distance, I'm usually most comfortable with my airbrush being 3 - 6 inches away.
In order to get a very fine application of paint with your airbrushed, you may have to move your airbrush much closer to your model - maybe 1/2 inch to an inch and a half. Also, your pressure will need to be turned WAAAAY down, (to prevent your paint from splattering over your model's surface).
In addition, I should mention here that some airbrushes, (like my weapon of choice, the Badger 150), have different sets of needles and corresponding tips to be used for fine, medium and heavy paint applications.
Mixing your paint and thinner
You can both mix your paint in and apply it from a small paint jar or a metal cup. Both usually come with your airbrush.
With a bottle, you can mix up a batch of thinned down paint, apply it and put the top back onto the bottle, using it later in future airbrushing sessions.
With a cup, you pretty much mix what you need, using it in your airbrushing session. If you have any extra left, you can pour it back into the original bottle your paint came from. Even though it's diluted, it can still be poured back in.
With the use of a cup, I tend to squirt my thinner in first (with an eyedropper), followed by pouring in the desired amount of paint. Then, using a trick I learned from a modeling bud (named Joe Smith), I dip a Q-tip into some thinner to get it wet, followed by pressing it onto the tip of the airbrush. I then push down and pull back the airbrush button. The air goes all the way through the body of the airbrush and is then forced back into the cup, with air bubbling in the paint & thinner mixture, mixing everything together.
Some potential airbrushing problems
There are a number of problems that one can run into while airbrushing. Some are listed below:
1. A dirty airbrush, (or one that has not been cleaned adequately), can cut down on paint flow, or prevent it from coming out altogether.