October 1, 2012

Thin line between thin lines and spiders - I

There is a thin line between thin lines and spiders (or splatters). Spraying with ultra low air pressures tends to make airbrush guns react in a more critical way to trigger action than is the case when using higher pressures. Using a low pressure is not always the best way to avoid the dreaded spiders. But if an airbrush is adjusted in an optimal way and tuned correctly, it is among the best solutions to spray fine detail.

Spider - rampant splatter of paint

Somewhere in the air pressure range is the optimal setting that allows to spray ultra fine lines without the paint suddenly blasting all over the surface before the artist was able to anticipate the occurrence of this event. The lower the air pressure the narrower that risk-free range becomes. But Low air pressures also allow to work in extremely fine detail. Most may wonder: why the heck take such risks? But I feel it is like driving a car real fast; the margin for error becomes smaller with the increase of pace, but it is fun to do.

To continue the fast car analogy, I look for a way to adjust an airbrush so that it handles predictably- that is capable of reducing the risk for spiders, like the a well designed car can handle high speeds without dashing into disaster. Apart from air pressure, the mix-ratio of the paint is also a matter to consider. Undiluted or paint to which only a small amount of water is added, will cause artists to involuntarily spray spiders sooner than mix-ratios with lots of water, because more pigment particles (that are more difficult to move than water particles) have to pass the narrow gap between the nozzle tip and the needle that moves inside of it.

As soon as the pigment particles are no longer surrounded by the paint's solvent because it has evaporated or has been blown away, and they are directly exposed to air, they seek to adhere to whatever piece of material they encounter. It makes no distinction between the needle and nozzle tips or the surface onto which the artist is spraying on; whatever material it encounters first in the given circumstance, it will hold on to as soon as it gets the chance to do so. It is the main property of all paints.

The paint is moved out of the paint cup because of the difference in pressure of the atmospheric air and that in the area surrounding the narrowed space between the nozzle tip which causes the air to travel faster, causing pressure to drop below the atmospheric air pressure. This is the venturi principle. Thus paint is persuaded by natural law to flow from high pressure area (in the paint cup) to the low pressure area (around the nozzle tip). The air flow exports the mixture of water, paint, solvent and air from the airbrush into the thin air between the airbrush and the surface on which the art is sprayed.

Venturi - Green = air cap, Orange - nozzle, dark blue = needle,
light blue = paint, brown is nozzle seat, grey = airbrush housing

It is difficult to spray anything worth looking at (in figurative art) when all the airbrush produces, are paint spiders. So, that is what most airbrush artists attempt to avoid. In order to be able to do that the following requirements determine the quality of the spray:
  1. the construction and material quality of the airbrush
  2. the level of adeptness of the artist's hand movement
  3. the quality of the paint
  4. the mix-ratio of the paint and water
  5. the air pressure in the airbrush
  6. the quality of the art work surface (and its preparation)
Assuming the above conditions are met or exceeded, that leaves the construction and quality of the airbrush to be crucial to create the conditions for successful painting. This is why crappy airbrushes will never work well - never be able to spray fine detail, less crappy airbrushes will limit the quality of an artist's work and excellent airbrushes will allow them to spray delicate, fine detail.

How to adjust and customize the airbrush I will describe in an other blog entry. This gist of this brief entry is to make artists aware of what is going on inside the device they are holding in their hand in preparation of the technical nitty-gritty that will follow. Nothing beats awareness. Unlike inflexible teaching methods, awareness allows human beings to figure out what is (or may be) happening, even in unexpected situations that can never be taught. And from such a mindset, determine what is the best action to take to be successful or be less affected by unfavorable circumstances.

For instance, if one is taught one or two solutions to a problem to which there are in fact several more that all affect each other, there is a good chance this person gets stuck. If, on the other hand, a person has acquired the ability to analyze a situation through logical thought in order to find the solution, there is a possibility that the problem may be solved.