Your problem is quite likely the airbrush. Master makes cheap Chinese knockoffs. Quality can vary. This is why I tell students not to economize too much. A decent airbrush can be had for less than $100.00. Less than $75.00 in many cases. Cheap tools are a false economy, and if you are inexperienced it can be impossible for you to tell if you are doing something wrong or if your equipment is having issues. Where were the bubbles coming from? Inside the paint cup? If so this probably means a loose nozzle (air leakage) or some blockage in the nozzle itself. Badger Modelflex should be mixed well (stirred, not shaken) before spraying. It is difficult to advise you not knowing what type of airbrush you have, but I would clean it, check and make sure the fittings are tight, you have enough air pressure (25 psi or so will work fine) and spray some plain water or windex through it. Seal any leaks with a little Chapsitck or beeswax on the threads. Hope this helps! If it doesn't work, post a pic of your airbrush and we'll see what other solutions there might be.