I was having a chat with a few of the other Bunnies about airbrushing and "dry tip" and we thought it might be a good idea to share our collective knowledge, plus hopefully learn a few new tips!
I'm sure everyone who airbrushes is already well aware of this phenomenon, but dry tip is where as you spray, paint accumulates and dries on the tip of the needle. This very quickly causes the airbrush to start spluttering and results in lumps of semi dried paint being flung all over your mini.
Sometimes you can scrape the dried paint off the needle with a fingernail, but it rarely works. This is a pain with siphon fed airbrushes, where you can remove the paint cup before removing the needle, but far more inconvenient if you are using a gravity fed airbrush. This is due to the fact that the paint cups are often irremovable, so you have to decant the contents before removing the needle to prevent paint seeping into the trigger mechanism.
Before I go any further, I need to stress that I am not an airbrushing expert. However, I have had a lot of success with the following tips and techniques.
If I am using acrylic paints I always use Vallejo flow improver. As I understand it, this retards the drying time of the paint slightly, reducing the opportunity for the paint to set on the tip of the needle. The instructions state 1-2 drops of improver per 10 drops of paint, but I normally just half the acrylic thinner and add flow improver. Whilst reducing dry tip noticeably, I haven't noticed any real difference it takes the time for my miniatures to dry.
Perhaps the best thing to reduce dry tip is lube. I used to dread airbrushing, but as soon as I started using this stuff it turned out to be a game changer. It has easily extended my spraying time to about 25-30 minutes without any issues at all. Plus it is dead easy to use.
When I strip the needle I simply dip it into the Iwata tube, or rub a bit on using my fingers if I'm using Regdab. It is that simple! I've also found that putting two drops into the trigger assembly keeps the action nice and smooth as well as protecting the O ring. The Iwata is super handy as you can dip the needle in. However, the Badger is a much better buy and a single bottle will last for years.
I normally wipe out as much of the paint left in the cup as I can, before spraying a blast of Premi Air Liquid Reamer into it. I'll then use a cotton bud to wipe out all of the residue it will have dislodged. I'll then squirt in some Medea Airbrush Cleaner. This stuff is really cool, as it will make massive bubbles lifting the residue out. To do this, simply spray using blowback(form a seal around the crown and spray). Once I have done this I'll remove the needle, and repeat the above steps. It sounds complicated, but once you have a routine you can accomplish it in about 2 minutes.