ELECTROSTATICS

"A COLOURFUL APPLICATION"

By: Michael Liang
Electrostatics is the study of charged objects in which the charges do not move hence the suffix “statics” or in other words stationary (Blake, p. 403). There are numerous applications of electrostatics in our daily lives. Here is just one example:
electrostatic spray painting

What did I watch?


In this video, you have watched a factory worker spray painting a railing. Nothing special right? Industrial work 101. At first glance, it is just normal spray painting; however, if you look closely you'll find that the spray resembles more like a cloud that a condensed shot of paint. You may also see that the worker has little need to go on the other side of the railing, as though he knows the the other side of the substrate will also be painted. The reasoning for all of these observations is all in the title of the video: “ELECTROSTATIC spray painting”.

What is it?

Electrostatic spray painting or "power coating" is a method of spray painting that is utilized to reduce material waste as well as overspray. Electrostatic spray painting is very convenient for capturing regular and uniform coating layers on various surfaces (Leneau). Almost any surface can be electrostatically sprayed as long as it is grounded and conductive (N/A) There are NUMEROUS applications to electrostatic painting. Here are just a few:


Brief History

Electrostatic painting was first patented in the United States in the late 1940s by a guy named Harold Ransburg. Many manufacturers realized the savings of materials that could be obtained through this method of painting as they quickly interpreted the benefits of his line of products of "Ransburg Electrostatic Equipment" (Spray Painting).

Below is a picture of Harold Ransburg:

How does it work?

The process of Electrostatic Painting can be explained in three steps:


STEP 1

The paint within the electrostatic paint gun must be atomized by converting the paint into very fine droplets aka particles. The particles at this stage are neutral. As they move through the spray gun, they then become statically charged through different methods depending on the design of the machine. For example, an electrode can be placed at the tip of the spray nozzle. This creates an electric aura that the paint particles go through, thereby charging them. Also the charge of the paint particles vary on the spray gun design (either positive or negative) (Hutchins).


STEP 2

As the particles prepare to exit the nozzle, the droplets have to travel at a high enough speed so they take the electrostatic charge from the aura with them. This gives the charge no chance for it to return to the electrostatic aura. Once the particles of the paint exit the nozzle, they spread out evenly as the particles repel each other. This is because the charge of the paint particles are all the same, being all positive or negative (N/A).


STEP 3

The paint particles are then attracted to the nearest oppositely charged, grounded and conductive surface. That is why metal is an ideal surface for electrostatic painting (Hutchins). The target object may also be a grounded neutral surface as through the laws of induction, become positively or negatively charged (Blake, p. 411).


Below summarizes all three steps:

Advantages of using Electrostatic Spray Painting

  • It is cost effective
  • There is no overspray
  • It is Hygienic
  • Unaffected by common cleaning solutions and disinfectants
  • It is Efficient -Work is done on-site; dries in about an hour and suitable for light use the next day
  • Creates less anger to staff
  • Creates less interruptions if in business

(Painters)

Disadvantages of using Electrostatic Spray Painting

  • Inside corners are extremely hard to paint (aka the Faraday Cage Effect)
  • If the target area is not grounded, the paint will then find the nearest grounded object instead

(Hutchins)

So why use Electrostatic Painting rather than Conventional Painting?

Normal spray painting only paints the surface that is directly in front of the nozzle. An electrostatic paint gun on the other hand, wraps paint all around the area. This makes sure that the material is completely coated with paint. Overall, this gives the material/area a coating of paint without unevenly painted spots you usually find with conventional spray painting (Spray Gun Industry).

BILBIOGRAPHY