Finishing Room Ventilation

For low-volume work with brush application of waterborne finishes, the ventilation system can be relatively modest. January 8, 2010

I'm setting up a finishing room that will only be using waterbased finishes, and no spray on finishes. The finishing room is small (10x10x12) and needs to duct to the outside through another room. Does anyone have any suggestions?

Forum Responses
(WOODnetWORK Forum)
From contributor L:
If you are setting up a spray room with a 10x12 floor and a 10' ceiling you will need between 10,000 and 12,000 CFM to pull the proper amount of air through the room (100 lineal feet times width by height). 475 CFM is only a change of air every 2 1/2 minutes. Just because it isn't flammable doesn't mean you don't need adequate ventilation for your health and for overspray control. The 1/100 HP gave me a good chuckle.

From the original questioner:
I'm actually not going to be spraying at all. It should be wipe on and brush on only. Does this change what you would suggest?

From contributor L:
I'd still put a 1200 CFM fan in there to get one room exchange per minute. You have to remember to design your room so you have a nice even flow throughout. It's not the easiest thing to do and a 1/100HP motor is really too weak to do it. The 475 CFM rating on that fan is free air and as soon as you start putting restrictions on it, ductwork, filters and such it will bog down to almost no air flow at all. Try to get something with at least a 1/2HP and 1 HP would be best. Just because it is a waterborne doesn't make it non toxic.

From contributor J:
I think contributor L may be erring further than necessary to the side of safety. You're not spraying, so you're not trying to evacuate overspray; you're just trying to get rid of whatever evaporates from the surfaces you're finishing. It's waterbased, so there's no explosion hazard. If you're not spraying then you'll be slow and won't be finishing large amounts of surface area at any given time, so the rate at which stuff enters the air is likely to be pretty low. I doubt you have much to worry about. Target's website includes a user's guide that suggests a fairly small fan (really a glorified bathroom fan) to clear the air even in a room used for small-scale spraying of waterborne finishes. Get copies of the MSDS's for the specific finishes you'll be using and review any health hazards; you should probably wear a respirator when finishing.

From contributor E:
I have a 9 x 20 finish room, insulated and only use WB spray finishes. I couldn't decide what to use for a fan so I built a simple box and used a home depot air blower. I set it inside the box, used furnace filters on the sides of the box and directly vent it outside. When it is hot, I turn the fan on low speed so I can keep as much air conditioned air inside as long as possible. Even spraying lacquers, there is almost not odor with this setting using my HVLP set up. I still use my respirator with this set up however.