Another vital topic within the airbrush technique is priming. Where it should be used everywhere, is somewhat optional, or must even be used, is clarified in the following article. There are also differences in the primers, which will also be discussed.
What is primer good for in the airbrush?
Primer is an intermediate stage between a painting base and the airbrush color. It should either seal the painting base and thus protect it or make the airbrush paint more adhesive. In most cases, the previously smooth surface is also “grippier.”
Not all painting grounds or surfaces need a primer. Sometimes you have to have it, and other times you can just use it as an option. The details are below.
When to use airbrush primer?
The first argument for using a primer is that the substrate is too dark, and you are basically only working with transparent airbrush colors. This is because both tones combine and produce a different color image. Opaque colors do not need this in a sense.
That’s why some experienced artists deliberately work with opaque colors from dark to light. So they use the dark background in black or blue right away as a base.
Examples are motifs with a night sky, dark rooms, or an underwater landscape. The parallel advantage is that you can save white paint or even the primer simultaneously.
On the other hand, it is basically necessary when spraying metal and models in the plastic area. This includes your 3D prints if they come out of the printer very smoothly.
Otherwise, there is a risk that the paint can come off more quickly, and the surface may not appear as homogeneous.
Usually, however, you would not need a primer in the nail area. Here you could alternatively apply the transparent colors after a “color primer” with the airbrush color white. Otherwise, use the opaque colors mentioned above.
With pure drawing cardboard or canvas, you do not need a primer. The substrate is already white, and the paint adheres well. An opaque primer serves here instead as the following secret tip:
Applying a relatively thick and almost dry primer with a bristled brush immediately acquires a coarse and exciting texture. You can use this effect, for example, to create skin texture in portraits of animal illustrations such as elephants or wet horns.
It is another beneficial effect for motifs with hair, such as people or animals. For example, if you want to work out the fine and individual hairs with a scalpel, you will not damage the background with such a gang primer.
By the way, this secret tip of a created or already existing light 3D structure should always be used for the surfaces:
If you spray a light mist of paint from the side (almost horizontally), the slight elevations and depressions come out better. This is then the basis for the skin structures, cracks, grains, or other possibilities of tactile and visible indentations of a unique natural surface that you want to simulate.
How to apply a primer for an airbrush?
The unique primer you have purchased for the airbrush can be applied with the same or best a nozzle size of 0.3mm.
Here you have to add a thinner in each case, which usually remains relatively small in proportion because the thinning effect is very high. Depending on the manufacturer, approximately 10 to 15 percent thinner is required for the primer.
However, if the mixing ratio appears to be too high or too low, you must add more primer or thinner. It is best to test the spray pattern on a similarly smooth surface instead of the object itself. Your disposable gloves would already do the job in this case.
Otherwise, the application is similar to the paint. This also means that you have to remove any dirt or grease from the surfaces beforehand. Especially in the modeling area or with fingernails, you should first wash them off with washing-up liquid. Light dirt can then be blown off with the airbrush gun.
Here you should also consider, even if the primer is declared as not harmful to health, that in case of doubt, you always wear a respirator and gloves, ventilate sufficiently, and if necessary, also use an airbrush extraction system.
Otherwise, always cover the surrounding ambiance if you need to protect it. Old newspapers or other documents are always crucial for the airbrush paint and even primers, so you do not spray your desk directly.
As a tip for model building: Hang up the model or fix a fixture on the underside of the model, which is not visible, or you also do not want to spray. To do this, take an old tin can and glue it in place with super glue. It will then serve as a temporary grip for you, which you can remove afterward.
If the surface color is not very different from the primer when applying the primer, make sure that you complete each pass without pausing. This way, you will see the “spotty spots” of the still wet primer better.
When spraying, always start at the side of the model or surface and move evenly over the area to be sprayed. This prevents the primer from running when it is still liquid.
If one pass is not enough, you need to do as many as possible to cover the surface well.
Difference between different airbrush primers
Primers are available from different manufacturers and are often also titled primer (used in English). There are various colors (white, black, gray, red, etc.), so you can already “play” with or take advantage of the respective color scheme.
In addition, they differ in the grain, which is especially interesting for modeling and gives other effects.
Finally, they differ in their respective consistency and can be used accordingly. For example, some lay very nicely over the rounded or angular objects in the model making and figure area so that a very smooth surface is already created after drying.
Some manufacturers give out the particular note that only one application is necessary and thus represents the last difference to be mentioned.
There are others beyond the primers mentioned, specifically about priming the airbrush. They are mainly then but according to the substrate and are thus the following:
Primer by spray can
The primer from the spray can is actually classically suitable for the metallic substrates. So it would be helpful and applicable if you are active in a custom painting or modeling with metallic objects.
In this context, it is essential to mention that you must first sand the surface with fine sandpaper, especially in custom painting, i.e., car or motorcycle paint. The primer will hold better after this step.
If the area is rusted, you should remove it and treat it with special rust protection.
The advantage of the spray can is that the surface remains relatively smooth, so you can actually start with the airbrush right after drying.
The disadvantage, however, is that if you are not yet so experienced, “runnings” may occur during the application, which you will have to sand off again at best.
In doubt and as an alternative, a spray gun is recommended for this spraying technique since the spray mist is applied over a much larger area and creates fewer surprises, which could sometimes occur undesirably at a can opener.
Priming by brush
Priming with a brush can always be used when the surfaces are also not even but rather rough or cracked. Natural wood is a classic example here.
The advantage of the brush is that sometimes you can’t get everywhere with the spray can.
In addition, unlike the spraying technique, you do not necessarily need gloves or even a respirator. However, this is recommended for spraying, as the primer remains on the fingers longer than acrylic paint, despite being washed off.
If you swear by smooth surfaces anyway, then the spray can or paint gun is the better choice since the brush stroke could leave at least fine lines (depending on the primer, brush guidance, and drying).