Shopnotes plan for a finishing booth

[Dave Schreib]

I see that shopnotes has plans for a finishing booth. Sometime in the future, I hope to buy some spray equiment. But in the meantime, I was thinking about this booth and the blower that is built into it to capture overspray and fumes. If I were to use such a thing in my shop, even if the shop were RELATIVELY clean, wouldnt the blower suck a lot of fine dust into the booth and onto the wet work piece? How big of a problem is this and what would the solutions be? Thanks

[Glen Butler]

Yes the blower will suck air from everywhere, and will easily carry fine dust, which is a huge problem. The solution is to filter the air coming in. My booth is a room that is separate from the shop and supply air comes straight from outside not through the shop. This helps the filters not clog so fast. You can get these from grainger, but simple furnace air filters will do the job as well.

[Faust M. Ruggiero]

Dave,
Yes and No. If you spray a slow drying finish, the dust will be a problem. I spray in my shop all the time. I have an 18" tub-axial exhaust fan with explosion proof motor mounted into an outside wall. It lives in a little enclosure on the shop we call the Swiss chalet because of its shape. I have outside doors on the enclosure as well as a door on the inside to secure from air loss. Inside the spray area I have a 6' X 6' x 2' deep filter area that grabs the overspray particles and keeps them from going into the atmosphere. A fabric wall on each side of the filter box attachs to double doors dividing my shop from the room the filter box is in. When I want to spray, I pull the curtains against the doorway to create a tunnel for the airflow and spray in the shop. I open enough windows to allow make up air. In the winter I heat the heck out of the shop a half hour before I spray. I blow down the shop with the fan running a little ahead of time. I spray solvent based lacquers that dry almost immediately and dust has no time to settle in the finish. Hey, it works for me and my finishes are very good.
butch

[Glen Butler]

I disagree. Dust is always a problem, but especially on a slow drying finish. It only takes one small fiber floating around to ruin the finish. And the smoother it is the more that hair will stand out. Filtering the supply air and turning on the fan a few minutes prior to spraying, as well as vacuuming and blowing off surfaces in the room, gives you nearly a "clean room" that will provide impeccable spraying results.

[Tony Bilello]

A common mistake is to have a small opening for fresh air to come in. This will cause more suction of dust and a draft.
The air flow through the spray booth should not be a draft. Just air moving. Many spray booths dont have a small opening. One whole side is completely open for complete air flow. Also, most people that spray, spray lacquer. The dust free time is usually less than five minutes. However, lacquer is not suitable for very small shops.
If you have a back door to your garage for cross ventillation, a small fan is all you need.