Airbrush artists know very well how easily the airbrush clogs by using some paints, like titanium white. I was just curious to see how the paint sticks to the needle tip causing clogging... So, I used an Iwata CM-B with an old needle and old nozzle, loading it with pure Badger white (without dilution I have the maximum coverage and the maximum clogging too) and I've set up a vertical microscope with 75x magnification:
|
This image shows the needle extruding from the nozzle and nozzle cap prior to spraying the paint. |
|
This picture was shot after one second of spraying the white. All the surface irregularities are covered by the paint in just one second. |
|
The color deposit continues on the needle while spraying goes on... |
|
When the paint deposit and its surface roughness increase, the air turbulence sends some pigment lumps back onto the nozzle cap too, however, the airbrush is still perfectly under control. |
|
When the paint starts depositing on the needle tip, the control of the airbrush is reduced. |
|
Here the control is completely lost and the paint doesn't flow anymore. Now we are at about one minute from the beginning of the experiment, after a light and uniform spraying of the white paint (this condition is the best possible for clogging). Checking the image carefully, the region around the nozzle tip results still clean. At this point, using the finger tips or nails to remove the dried paint is a common practice. However, this action can easily damage the delicate needle tip and it should be avoided. Therefore, it is much safer to use a solvent loaded fine brush to remove gently, quickly and efficiently the paint. |
|
Once the paint has been removed by the brush and the solvent, the airbrush control is regained completely and we are ready to start again... |
Checking the image below carefully, the needle region (pointed by the red arrow) near the nozzle is clearly free of paint.
The irregular paint coverage around the nozzle tip is due to the needle which is not centered in the nozzle. The image sequence below show the needle extrusion from the nozzle. This type of misalignment is not a specific propriety of my airbrush, but it is very common (as Eddy told me already and I just confirm it)...
The airbrush of my choice is an Iwata CM-B, and according to the Custom Micron technology, its' head system is hand matched for a perfect spray pattern. In the images above, actually, a perfect alignment between nozzle cap and nozzle is noticeable. However, the needle and the nozzle are not aligned, even if the needle shape matches the nozzle for a perfect sealing. Changing the needle, the image below appears. There is no change in the alinement.
Actually, turning the needle around or changing it, the misalignment doesn't change. The reason for this is that the needle is kept in place by the needle chucking nut and a couple of o-rings: their alignment defines the needle position in the nozzle. However, this common misalignment doesn't seem to influence the airbrush control.
Link to the main page of Color Experiments.
Updated the 13th of October 2006 by Zsolt
