April 6, 2014

THOROUGH airbrush cleaning

All airbrush artists are familiar with the contamination of their gun(s). Performance decreases as more waterborne paint residue builds up inside the airbrush. There are many airbrush cleaning fluids and tools, most of which don't work too well. Ultrasonic cleaners work well, but are quite expensive most of the time and require the airbrush to be soaked and treated inside the cleaner for a while. When artists are in a flow, they don't want to wait, but traditional cleaners do not do a particularly good job.

The stamp loupe I use.

When using a common airbrush cleaner, small chips or clusters of paint are left inside the airbrush housing, the nozzle and on the needle. Most never check this, but if they would look at their needle using a stamp loupe, there will be small chips or spots on the needle. If after cleaning again the needle is extracted from the airbrush and observed again under the loupe there will be chips of paint in other places. Sometimes up to 20 times (!!!) of cleaning, extracting and observing the needle before no more residue is found (depending on the brand of paint - some brands are more stubborn than others).

Stubborn needle contamination still present
AFTER several times of cleaning of airbrush.
Click photo above to see the enlarged image.
Image was shot with a Bresser USB microscope.

Regular cleaning agents don't do the job. Thinner works a little better, but leaves residue as well and urges to spend much time and effort cleaning. By far the best liquid I have found so far is HG Oven, grill and barbeque cleaner; it radically removes paint better than any of the above mentioned liquids and gives the airbrush a nice shine on the inside and outside (and hopefully does not dissolve the airbrush over time...).

HG cleaner.

When is it time to clean the gun? If the period in which the airbrush sprays ultra fine lines starts to decreases and the gun becomes unpredictable - suddenly spitting blobs of paint (that result in the dreaded 'spiders' - it is time to clean. The blocking of paint followed by the sudden ejecting of too much paint is caused by residue that has build up in the area where needle and nozzle meet. Also the color of the spray starts to change, because some pigments adhere to each other faster and more tightly than others and paints are rarely made of one type of pigment alone. If these things happen you can bet your life that there will be chips and spots on the needle (and the inside of the airbrush) if the needle is observed under the stamp loupe.

unpredictable blotting and color change spraying results

The cleaning is done by spraying a little of the HG liquid in the airbrush' paint cup (to approximately halfway) and then letting the liquid bubble inside the cup by placing the finger on the nozzle exit. Before doing so, slightly pull back the needle - it is razor sharp. I start with a moderate amount of air, so that the bubbles (tiny shock waves) properly wash the inside of the airbrush and the needle tip. Gradually increasing air pressure so that the HG liquid containing paint chips and residue all exit the airbrush through the paint cup instead of clogging the nozzle again. I do this above a rag or old cloth so that things don't get too messy.

Send liquid and paint residue backward
through the airbrush by blocking the
nozzle with a finger and letting air
flow through the airbrush

After doing this once or twice - intermittently checking the cleanness of the liquid by sucking it up with a pipette and looking at it against a light source - all residue and chips will be removed and the airbrush is squeaky clean again. When the liquid looks transparent, you're done.

Sucking up the HG liquid with a pipette
to check if there is still paint residue in
the airbrush.

This method of repeated cleaning and checking ensures most of the paint residue is removed and the checking of the needle with the stamp loupe in between the flushings will give the artist a pretty good idea of how clean the gun actually is instead of gambling that the promotional texts of cleaning agent manufacturers are true.

Controlled cleaning with intermittent visual checking with a loupe works better with gravity feed airbrushes (parts of the internals to clean are easier to reach), which is why after a long time I decided the Iwata HP-BH works better for me than the CM-SB, because cleaning is of utmost importance for artists that often spray very fine lines. The inside of Iwata airbrushes is difficult to reach, especially since removing the tiny and delicate nozzle often is not recommended. The HG liquid adequately removed the paint residue and chips (I use Vallejo Premium that has very strong adhesive quality) and the checking with the loups allows to determine if the airbrush is really clean.

Johnson silver polish.

I've discovered that it pays to polish the needle between each session. I use Johnson silver polish (image above) that I drip onto a small piece of closed cell foam. I move the needle through the blot of silver polish with long strokes, slightly turning the needle after each stroke. It takes about 5 minutes to polish the needle to a perfect surface. The next session the airbrush performs perfectly.

Maintaining an airbrush in this way will cause the gun to spray the finest lines it is capable of for an extended period of time and make it spray areas flawlessly even with very low air pressures.