Where is the damage?

You often hear the claim that an airbrush must be disassembled for cleaning after each use. 

You've also heard the other side claiming that disassembly damages the airbrush and you should not disassemble the airbrush, except to repair it. 

The airbrush relies on a venturi effect to function. This means that the head assembly must remain airtight to prevent air leaks which would compromise the venturi effect.

The head is attached with airtight brass threads. The brass threading tolerance is high, allowing an airtight seal, but repeated reassembly will erode the brass threads to the point that it can no longer sustain an airtight seal. 

The result is a leaky airbrush head at the threads, as seen here in the bubbles appearing after soapy water has been applied.

In this case, the airbrush artist usually resorts to pliers to tighten the head further to prevent air leaks. However, too much torque will distort the body of the airbrush further eroding the ability to create an airtight seal around the head. Most of the damage occurs during the reassembling of the airbrush.

.Once the airtight seal is lost, the airbrush will forever require beeswax on the threads of the head assembly. That means every time you take the head off you'll need to patch the leak.

While it's true that the head can be replaced, the damage to the body of the airbrush is permanent. 

Most of the damage occurs during the reassembling of the airbrush. So be hesitant to disassemble your airbrush needlessly.