Whether you're painting with aerosol cans, an airbrush, or an HVLP system, paint fumes and overspray are a given. Respirators are and should always be your first line of defense. While some fumes aren't super toxic, most are, and will linger in your work space. Instead of wearing your respirator when you're done painting for the following hour or more, eliminate the fumes and over spray with a spray booth.
The paint booth in this instructable is a large sized home version, but the basics of my build could be applied to a smaller bench top version. Have a look, learn the basic set up, and build your own booth to save your lungs and health.
Step 1: Size Matters
I started off with the booth itself. If I can spend a little money to save a lot of time, I will, so I searched for an existing cabinet that met all of my requirements.
The following is how I decided to go about my search: One component I wanted to have with my booth was doors. Also, I paint items in a variety of sizes, from as small as 6" in length, up to 36" in length. I started looking at used entertainment systems. I found a lot of them, but none that met my size requirements for both the space in my work area, and/or inner work booth area.
Next I searched for large cabinets, and found just what I needed, for $35! It has a metal frame with MDF walls. It's heavy! Ideally, you want an all-metal paint booth, due to potential fire hazard, but the MDF walls made a great material to work with for the inner frame assembly, as well as cutting the fume outlet.
I cleaned the dust off, moved it into place, and painted the outside of the cabinet to brighten up my work area. I stepped in the cabinet for size reference.
Step 2: Filter Support Frame
I drafted two different setups (A & B) for the frame that would hold the filters. I went with my second draft (B). It was less complex, and gave me more filter area to catch paint over spray.
I built the frame with 1" X 4" studs. This frame isn't holding much weight, so no need for anything bigger. I screwed the wall studs to the wall from the outside of the booth cabinet. The horizontal support studs are held in place to the wall studs, with screws.
This cabinet came with a heavy duty metal shelf, so I added supports for the shelf. I use it when I'm painting smaller pieces, and take it out when painting bigger pieces.
Step 3: Filter Frames
The wood frame from the previous step now needs individual holding frames for the fiberglass filters.
I used 3/4" aluminum L bars, from Lowe's, to make the frames that hold the fiberglass filters in place. The L bars came in 8' lengths. The 45° cuts were made on a miter saw, with a normal wood cutting blade. Being that the bars are aluminum, they can be cut by hand with a hand saw, but the process will take much more time. The L bars are held together in the corners with screws through a small 90° metal bracket, backed by wooden supports.
Instead of buying expensive wire mesh to support the fiberglass in the holding frames, I used chicken wire I already had sitting around. This made a cost effective solution, but was in no way, easy work. The chicken wire wraps underneath each wooden support along the metal frame. I had to individually remove each wood support, stretch the wire tight to that point, put the wood support back in place, and then screw it down.
I made three individual holding frames, each one the width of the interior of the cabinet. I divided the length of the stud frame by three, to get the individual lengths for each filter frame segment. Because the filter wall frame leans back, these filter holding frames easily stack on top of each other without the need to be anchored to the stud frame. Why not make it one big filter frame? I purposely chose to use three segments for efficiency. I knew the filters would build up paint over spay, quicker, in specific areas. With three individual filters, I can rotate or replace just one piece at a time, instead of one big sheet that isn't adequately used to it's full potential.
Step 4: Over Spray Filter
Of all the varieties of paint filters available, I choose to use a 15 gram, fiberglass arrestor, from Spray Booth Filter & Supply. I got it in a 300' X 20" roll, 300' of length so I won't have to buy it again for quite a long while, and 20" wide to meet the width requirement of the holding frames.
This fiberglass filter easily cuts with a pair of scissors. I simply measured out the lengths I needed, and cut each one off. Again, because this filter wall leans backward, the filters easily stack on top of each other without the need for reinforcement to keep them in place.
I neglected to photograph the filters before they got a lot of use, hence the well used filters in the photos.
Step 5: Exhaust Fan
The size of your exhaust fan depends on the size of your booth. I used an HVAC fan for two reasons. First, it's made to be strong enough to push air through a home duct/ventilation system. Since my booth is larger than a bench top version, I wanted to be sure my fan would properly evacuate paint fumes from my painting space. Second, I already had one at my disposal.
The motor of my fan is not explosion proof, so I had to make modifications to the fan housing. Instead of the fan setting INSIDE of the booth behind the filter wall, and exhausting out of the booth, it had to set on the OUTSIDE of the booth, drawing out the fumes from inside the booth.
To modify the fan housing, I first removed the metal shield grid from the housing that would be the inlet side. The opening there is about 10". I mounted a 10" take off to the inlet with machine screws. The take off has a self adhesive strip, but I also went around it with duct tape. Screws, adhesive strip, and duct tape. I don't mind overkill sealing this off, since the whole point of this is to prevent toxic fumes in my work area.
The next modification I made was to the fan outlet. I had to go from a rectangle, to a circle ( 8" take off ), to accommodate for the outlet duct. I removed the shield grid and cut two pieces of thin sheet polycarbonate to match the size of the grid. I traced the diameter of the 8" take off onto the polycarbonate, and cut it out with a jig saw. I bolted the polycarbonate sheets together, one on the outside of the shield, and the other on the inside. The 8" take off was mounted to the polycarbonate, over the cut out holes, with an adhesive strip, and bolts. I caulked the bolts, and every edge of the polycarbonate sheets for a maximum seal. With the modification to the outlet done, I screwed this piece back onto the fan housing, and wrapped it's edges up with duct tape.
Step 6: Fan Mount
I had to set my fan on a couple of 2" X 4"s to have enough clearance for the inlet to not hit the bottom of the booth floor.
I traced around the inlet take off onto the booth wall, and cut the circle out with a jig saw.
Once the fan and inlet were slid into place, from the inside I caulked around the hole, and then wrapped it in duct tape.
Step 7: Get It Outta Here!
The only thing left to make this spray booth fully functional is the outlet duct work. Must get those fumes out!
I used 8" flex duct, just like you'd use for a clothes dryer, this just has a wider diameter.
From the outlet on the fan, the flex duct runs to a vent that outlets through a window. The glass window pane was replaced with an adequately thick sheet of polycarbonate, that I cut a hole out for the vent port, with a jig saw.
Step 8: Lighting
I used fluorescent lights to brighten up the space in my booth. I had an extra 4' fixture that I used. I eventually will have a second set of lights in my booth, but this works for now. In the future I would like to paint the interior walls white, or apply a reflective material that will greatly brighten up the inside of the booth space.
Using screws, I anchored a couple of wood supports, cut from a 2' X 4', to one of the booth doors. I put the light fixture between the wood supports, and anchored it by screwing through the fixture, into the supports.
Now, it's ready to use!
Step 9: Completion
And with that the booth is complete!
Here are a couple examples of what I paint in my booth.
The video shows how convenient it is to spray objects; I can then close the doors and continue to work on another project.