Airbrushing Liquid Flux
© Jeffrey Herman


I used to use a spray bottle to apply Gesswein’s Dr. Frank’s Fabulous Flux to protect against firestain. The problem was, when applying liquid flux with a sprayer, the large droplets would produce voids on the object’s surface which would have to be resprayed. The flux would also build up a thickness that would occasionally bubble off solder pallions.

Recently, when visiting a local hobby shop, I noticed a number of airbrushes in their display case. For years I had contemplated using one as an applicator, but didn’t want to spend the money. However, next to the professional airbrushes I saw a $28 Badger 250-4 airbrush with a four-ounce reservoir that I couldn’t pass up – it was worth an experiment. I also purchased a $5 brass accessory that allowed me to connect the airbrush to my air compressor. I raced home, excited at the prospect that this inexpensive, elegant solution would solve my flux issues.

I found that the airbrush assists in depositing a finer, even layer of flux, and eliminating the bubbling that would normally occur if applied by brush or mist sprayer. There is also a volume adjustment. And the lack of bubbling flux keeps pallions in place. Also, since most of the liquid evaporates with this applicator almost immediately after applied to a torch-warmed object, there are no voids left on the surface to have to re-spray. This method puts flux just where you need it, reducing waste. The airbrush should work well with other liquid, non-flammable fluxes.

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