To be safe when running copper air lines, clean the ends if the tubing with sandpaper and the fittings with a fitting brush, and use a mild flux like Rectorseal Nokorode. Stay away from any flux marked as "self cleaning" as they all have acids in them that will corrode any metal they contact over time. The only way to get rid of the residue is to flush the lines with hot water.
Given the price of copper tubing and fittings, and fittings like sharhbites in particular, it's hard to justify using anything other than PEX for air lines in a small to medium size shop. The burst strength is about 3X the highest air pressure you'd ever run, and if it springs a leak down the road it doesn't explode like PVC. Just keep it out of direct sunlight and it'll last for years. The crimp ring fittings aren't expensive, and stainless ones are actually a bit cheaper than brass.