Why air bubbles appear in your airbrushe's paint cup and how to solve this issue.
If at any point you are ready to paint, and you notice that instead of paint coming out of the airbrush nozzle when you pull the trigger, bubbles come out of the airbrush cup where the paint is, you are most likely experiencing a phenomenon called "blowback". Although sometimes blowback generated intentionally by obstructing the air and paint outlet of the airbrush nozzle with our fingers can help you clean the airbrush or mix the paint, when it occurs in a non-"programmed" or intentional way, it can become a big, annoying, and worrying problem. Here is a quick and easy guide to identify why this is happening and how you can easily fix it.
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What Causes Uncontrolled Blowback in an Airbrush?
In a dual-action airbrush, air flows around the needle while the paint is pushed out by that air through the nozzle, specifically through the space between the needle and the edge of the nozzle opening. If, for some reason, air sneaks into the paint channel, this will push air bubbles into the cup. This annoying effect usually happens when there is an air leak at some point where air and paint should be kept separate.
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The three most common reasons for this to occur are as follows:
1. Loose or Misaligned Air Cap
· This is the easiest solution: if the air cap is not tight or has paint residue or dirt on it, the air escapes and mixes with the paint. You should always make sure that the cap is tight and clean. Also, as an additional measure, check that the tip of the nozzle protrudes slightly, this is indicative that at least the cap is completely screwed into the body of the airbrush.
2. Cracked or Damaged Nozzle
· A nozzle with cracks allows air to filter into the paint channel. These cracks occur in airbrushes where the nozzles must be screwed in, so said cracking is the result of overtightening it. It also usually occurs if you push the needle forward too much, this pressure could eventually cause the tip to crack if it is a constant practice. It could also occur because the needle is bent. Check the nozzle well; if you notice any cracks or deformations, it is the best time for you to replace that part.
3. Poor seal between the nozzle and the airbrush body
· Airbrushes, whether they have self-centering nozzles or threaded nozzles, always require that the seals or gaskets are in perfect condition. Over time, the seals or gaskets that the airbrush possesses tend to deteriorate. In the case of airbrushes with self-centering nozzles that usually use PTFE seals, the joining surfaces could be scratched, dirty, or simply the PTFE rings could wear out, in all these cases, air would filter into those places and mix with the paint. To avoid this, make sure that the nozzle is clean and that it fits evenly against the body of the airbrush, and change the seals if necessary. In the case of airbrushes with screw-in nozzles, these have an O-ring that could become deformed or broken over time. If in these cases you notice that this O-ring has been deformed or broken, you should change it. In case it is not broken but deformed, a provisional measure until you find a new O-ring is to place a little Teflon on the threaded part, which will momentarily prevent air from seeping through there.
Additional Tips:
• For Self-Centering Nozzles: Make sure to check that the air cap and the surface where the nozzle sits are in perfect condition.
• For Threaded Nozzles: Be sure to tighten them carefully to avoid leaks or cross-threading. Also, periodically check that the O-ring is in good condition. If you notice any minimal breakage or deformation, consider replacing it with a new one.
• Cleaning: Avoid using metal brushes to clean your airbrush, as these brushes can scratch the nozzle and other internal parts.
A Quick Trick
If you suspect that the seal on a self-centering nozzle is failing, try turning the PTFE ring around as a temporary solution, but remember to replace it soon.
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By following these steps, you can identify and resolve most causes of blowback, so you can keep your airbrush running smoothly. Also, remember that if you need spare parts or suitable tools for airbrush care, at SprayGunner we have everything you need. In our store you can find everything from replacement nozzles and seals to all kinds of essential accessories to use with your airbrush!
Check out our YouTube video where the Bubbles in Airbrush cup problem is explored and explained: