Master spray booth tech here literally. Any brand you can likely name I have extensive experience with. All dirt is impossible to avoid, the air is filled with too much everywhere on earth. The best way to keep dirt off your fans/out of your booth is to stop leaving ANY of the doors open at any access with the system not operating and even loading/unloading needs to have the system running. Dirt is always moving in the air, and if the air is moving so is the dirt suspended in it. If the air stops movement the dust begins to settle, inside your booth and on your fans. If the system remains running the dust will have a far greater tendency to move toward the filters with the airflow current than settle on things. Load the work in your running booth, and then with doors shut give at least 2-3 min before spraying to allow the air to travel (booth running in spray/ready for paint) from the loading doors area of the cabin to the extractions filters or the duct for it, and "let the air clear" for a minute before spraying it. And never blow or sweep out your booths. Buy a damn dirt-cheap disposable bag system house vacuum, the disposable bags are cheap too. The bag systems let less dust pass through than the bagless ones so it is cleaning/filtering the air it sucks through it also. Now when the booth needs cleaned vacuum it out instead, with the booth doors closed, running in spray mode using the hose/brush attachments to get any ledges and top edges where it settles too. Over-pressurizing in spray mode also causes a lot of dirt stirring when applying product also, .02"-.03" W.C. is "plenty" of positive cabin pressure. a short dozen or so tiny items of negligence in the operator process cause very expensive and usually unnecessary service calls over dirt. But even if it is only a cheap manual damper in the exhaust to adjust cabin pressure, if you don't have it...get it! The overspray in the cabin has no choice but to recirc right back onto the ceiling fan AND onto the car if it is not evacuating the cabin correctly. Your dried suspended overspray then becomes the dust you fought so hard to keep out. In reality, a properly managed/staffed/equipped shop with one decently running and maintained bake-capable booth should reasonably put out 5-7 finished/billable jobs per day but there is the ever-present commonly accepted "buff every job out the booth" mentality is killing your overhead. If you buff more than 2-3 out of every 10 cars out of a down or cross draft booth that has filtered intake/extraction...something is very wrong with your application process. Do you know where I looked for this described miss-management scenario first when I was still servicing? The top of the ceiling fan blades if it has any in the booth. If dust accumulates there, it is slung off the entire time the fan spins. Spent a couple of days at a shop in Utah, I want to say maybe the Provo area but can't recall, it was a one-time visit and "once upon a year" to see why he had so many dirt troubles. Had a nice, decently maintained, and well-running side-by-side pair of SprayBake booths. After a literal top-to-bottom of the entire system and the shop itself (building pressure is another issue, but it's real & why your shop has an inch of dust on everything up high/in the ceiling!), and had to hand a large bill with this explanation: ~"Sir, your shop is a great setup and your equipment is impressive for its age being in the perfect working condition in which I find it. It all operates very nicely and is up to par for even factory SprayBake manual standards and I hate to report to you that your entire prep and paint crew are making expensive process mistakes every minute they operate your shop and are more than %90 responsible for every car you buff before invoicing."~ I had kids sanding bumpers in front of the loading doors barely clear of the door swing track and blowing them off pushing clouds of primer dust inside the cabin before briskly shoving them in for prime and the booth system was off the whole time. The booths were a Siamese configuration connected with a pass-through mix room between/adjoining them and they'd leave the doors propped open slightly, have one booth running and the other off/doors open spraying in the running ones after the prep disaster described! I have extensive SprayBake experience with all their generations/models and an extensive relationship with the owner of spraybake-booths.com/ and we know each other on a first-name basis is why I was sent there. Any booth can paint at least "well" if the operator learns/knows the system's proper use correctly.
