October 6, 2012

The future of airbrush is ultrasonic

Possibly the Iwata Microns (and their tuned variations) mark the end of an era in which the limits of mechanical and chemical design have been reached. The mechanical limitations are caused by the physical options of the construction of airbrush guns, the chemical ones by the paints and additives. So after the Microns different ways have to be found to make airbrushes produce a finer, more consistent and easier to control spray.

Ultrasonic atomizer

When giving these matters a thought, I was thinking of ultrasonics as a means to improve the above mentioned properties. There are several reasons to follow this train of thought:
  1. Ultrasonics are capable of producing ultra-fine particles (down to approximately 1 micron droplet size)
  2. ultrasonics are capable of disintegrating particles in solvents which makes solutions better suited to generate fine jets - low viscous fluids can be made to flow better
  3. ultrasonic constructions can drive fluid paints with little or no air (that is the component that causes paint to adhere to surfaces it encounters)
  4. ultrasonic waves are used to clean surfaces (ultrasonic cleaning devices, ship's hulls etc.) and reduce drag (experimental airplanes). This property can be used to keep the internals of airbrushes clean

There are two fields of application for ultrasonic waves:
  1. Fog generation, which requires wave generation in the Megahertz range
  2. Cleansing, which requires wave generation in the Kilohertz range

The properties mentioned in 2 and 3 will significantly prevent paint from clogging in the areas where it leaves the airbrush and comes in contact with air. Ultrasonic vibrations could also be applied to the airbrush' tip parts which makes it more difficult for paint to adhere (clog) to these parts, analog to ultrasonic vibrations being induced to ships' hulls to avoid adherence to them by a large number of particles that are present in water.

Not needing (a lot of) air to drive out paint makes air compressors as are currently used superfluous. Varying the frequency of the ultrasonic generators will allow the artists to use finer or more course particles to spray with. All these features focus on fine detail work. Typically, standard airbrushes generate 50 - 60 micron droplets, while ultrasonic atomizing transducers are capable of producing droplets of between 1 and 5 micron. Spraying larger areas would probably not be very efficient using ultrasonic techniques. Paint manufacturers would probably also need to change the formulas of their paints to work with ultrasonic airbrushes.

The video clip above shows high-speed recording under a microscope of a water droplet being agitated by ultrasonic waves (a low frequency household ultrasonic generator in this case). The ultrasonic waves cause the droplet's surface to ripple (disintegration) which results in a fine particle fog.

I will add information to this blog entry as I do more research on the application of ultrasonic devices. This is just the first brainstorm concerning possible future airbrush constructions. I have not yet considered technical and commercial aspects enough to paint a realistic picture of such constructions.