Spray Booth Exhaust System

[starman]

Have any of y'all built a spray booth for air brush work?  If so, how did you set up an exhaust system?  I have projects I need to paint, I have an air brush, I am building a spray booth about 20" x 20" x20".  Any help will be appreciated.

[doctorwayne]

I built mine, over 40 years ago, using part of an old end table for the base.  I used some light aluminum angle-stock and a pop-riveter to build the sides, back, and top using 1/8" Masonite.
I also added a turntable, made from 3/4" plywood, but I've never had need to use it, as I usually hand-hold most items to be painted.
I used a piece of galvanised furnace plenum on the top for installing the vent fan (which was a left-over from an old air-hockey game) then added some plastic dryer-vent hose, coupled to a louvered vent outdoors.
The photo below shows it in my basement workshop, but the paint odours were still causing some difficulties for my wife, so built a small insulated room (about 4'x6') in our detached garage (formerly a house and then a barn...and now roughly 180 years old.

 
The only change there was to replace the plastic dryer-vent material with aluminum duct pipe.
I keep a portable electric heater in that room, which, after an hour-or-so, is perfect for painting in the winter, even when it's -30º outside.

I use fibreglass furnace filters, cut to fit, to slide into tracks below the plenum holding the exhaust fan, which keeps the fan blades reasonably clean.

The reason for pre-heating the small room in cold weather is mainly to prep my rotary compressor (a twin-screw type in an oil bath) so that the oil is viscous enough for the compressor to work properly.

A couple views of the compressor...
 

In the past, I've used piston-type compressors and diaphragm types, too, but this one is the best I've found.  The compressor runs continuously during painting...there is no pulsation, and  I've never had water or oil in the air supply, and despite what's shown in the photos, there's no storage tank for air. 
My late father built this set-up, and while I don't exactly know what all the other parts do,  I've never had a single problem using it.

Wayne

[starman]

Hi Wayne.  Thanks for your reply!  I like your setup.  Is the track for your filter inside the spray booth and is the fan inside the plenum?

Jack

[PC101]

At the time of the build of my all sheet metal paint booth, I used a external fan (because of solvent paint fumes) with a internal blower wheel. Flexible 4'' aluminium Dryer vent exhaust pipe goes out a window pane area with the glass removed and fitted with sheet metal and a metal dryer vent hood. All paint being sprayed has too go though a 12''x24''x1'' furnace filter (the filter catches most of the paint overspray) then around a baffel (too break up the air flow) then though the blower wheel.  

Above picture. Filter goes in though the top, if you do not have the overhead room, go though the side. The sheet metal panel above the filter can be raised (for taller 12''+ filters, depends on the cost at the time of need) and can be taken out though the top.

Above picture. The external motor with internal blower wheel.

Above picture. With the filter removed you can see the baffel in front of the blower wheel opening. Before the baffel was installed I noticed the paint being sprayed would build up around the center of the filter.

Above picture. Baffel moved to the left of the blower wheel opening to see the blower wheel.

I did a smoke test with out the baffel with the blower running and saw how the "air stream" would draw strongerthough the center of the booth, so the baffel breaks the air flow some. Defuses the air flow I think some would say. And yes start the blower minutes before you begain to paint to clear some dust from around the area. And just in case if you need it, do not forget fresh ''secondary air", you do not want to pull water heater or furnace exhaust in to the paint room. I am sure my motor draws more cf of air then Wayne's does so less air flow would be better.

Oh I have small sheet metal shop with rollers, shears, brakes and folders.

If you have any Plumbing and Heating shops around you, see if they have any ready to junk Water Heaters or Hot Air Furnaces with Inducer Motors laying around. Most I.M. would have a 2'' outlet.   

 

[doctorwayne]

starman

Is the track for your filter inside the spray booth and is the fan inside the plenum?

Yeah, the track is just some strip wood nailed together into "L"-shaped brackets, then fastened to the underside of the spray booth's top.
The cut-to-size furnace filter is then slid into place, right below the exhaust fan.
Depending on the amount of painting being done, the filter is replaced as needed.

The exhaust fan is a couple inches above the filter, in the metal plenum.

There is a close-able screened opening, low on the room's wall, to provide make-up air when the exhaust fan is operating.  While I find the exhaust fan surprisingly capable of removing paint fumes, I've always worn a two stage respirator when airbrushing, as I use both water-based and lacquer-based paints.
I got used to wearing a respirator working in a steel mill, so don't find it to be a hindrance.  It's much easier to wear than the full face masks used, in conjunction with back-worn bottled air, when there was a gas-leak alarm in the mill.

I've always been puzzled by spray booths with the exhaust opening in the back of the booth, and more or less right in the path of the sprayed paint.  I'm sure that it works well, but not likely for long before the filter gets plugged with paint.
I'm sure that my set-up isn't as efficient in that manner, but my goal is mainly to remove the fumes, not the paint...or at least not the wet paint, but the almost dried paint dust, which does collect on the filters, but still allows the fumes to be expelled.

I did do some painting last winter, but will soon have three or four steam locomotives to paint in a couple of weeks, along with some scratchbuilt postal cars.  If I can tidy-up the paint shop, I'll try to take a few pictures.

Wayne

[PennCentral99]

I use an old kitchen hood vent for my spray booth/airbrushing operations. I laid it on it's back and mounted it to a workbench/tabletop. To provide more room inside the hood, I reversed the fan so the motor sits outside the hood.

Since I mainly use acrylic paint and do the painting in the garage, venting to the outside isn't much concern. I merely use a 12"x12" filter over the fan opening to capture the paint overspray before it reaches the fan motor and blades.

For lighting, I mounted a strip of LED's inside the hood and have some lights on clamps to give a "spotlight" effect.

I mounted a regulator/moisture trap on the outside of the hood, which is fed from my shop compressor (which also has a moisture trap).

Although this video is titled "Regulator for Airbrushing", it shows the airbrushing station set-up.

Terry

[SeeYou190]

Mine is routed out through a dryer vent using 4" tubing.

-Photographs by Kevin Parson

Click in the link to view the entire thread about building my  Ultimate Hobby Paint Booth for painting models.

-Kevin