Abstract: A sand-blasting apparatus which is operated by a vacuum system, wherein there is provided a sand-blasting gun having an air-inlet passage and a sand-inlet passage. Air is discharged into a mixing chamber, creating a vacuum therein to suck sand through the sand-inlet passage, and to discharge the sand under high-velocity so as to impinge against the surface to be sanded, the sand being captured within the enclosed discharge end of the gun and then returned to the sand-storage tank under a return vacuum arrangement defined by a continuous low-vacuum flow and a controlled high-vacuum flow, the high-vacuum flow being activated when the trigger valve of the gun is operated.