Paint Fumes Question

[LarryA]

Hello: I'm new to this board and hope someone can help. I'm making a paint booth to use with my airbrush and need a bit of information to complete my mock-up booth (making from cardboard first to work out bugs).
Here's my question:
In a give confined space will paint fumes hang low to the base of the space or rise to the top? This is important so I can figure out where I need to place my fan(s) to provide the best collection and exhaust of the fumes. I am planning on using two 4" 12 volt computer fans to expell fumes and a dust to vent them to the outside and was was thinking of placing one high and one low and using some sort of baffle to prevent the fans from just pulling from the area directly in front of them.
I'm open for suggestions here. I will mostly be using acrylic paints with very little enamel or lacquers.

[stevenoble]

The Tamiya Spraywork Painting booth has the fan in the middle at the back.I assume it will remove fumes from the bottom of the booth or the top by being placed in the middle,so you get the best of both worlds.I would imagine the paint fumes would be fairly heavy myself and sit at the bottom.

[KevHw]

Hey, I mostly live in my flat so there isn't any acceptable place to spray, and my balcony was slowly getting overspray which wasn't good!

So I made a very basic spray booth from a large cardoard box I had and I added a 12V 8cm centrifugul fan to the side. Had it running on just a 9V battery but if the air was thick, I'd hook it up in series to two 9V's.

I use spray cans so the spray is a lot bigger than with an airbrush I'm guessing, so the box can fill up quite easily. The fumes don't sink down because the box shields the inside air from the more turbulent outside air. That's why having a fan helps so much because it sucks the relatively still air out. If you want I'll post some photos of mine to show you. Just make sure you have an exhaust outlet, where the air from the fan is directed outside, and not into the room.

I've only got the one fan on the right-handside but I'm hoping to link up another (slightly less powerful) fan on the left to create a proper flow of air.

[Klaus Raddatz]

LarryA,
To answer your question, overspray particulates generally falls to the booth floor. Solvents, can fall or rise depending on the solvents in the thinner or reducer being used. When the booth is designed correctly, there will be enough air flow to prevent settling. The majority of overspray will get pulled into the filters, and you shouldn't have any overspray rolling out of the booth back at you.

I have to agree with Steve's suggestion to place the fan in the middle of the back. It's the best compromise in a cross-draft booth.

Here's a link to some additional info on booths and fans: http://modelpaint.tripod.com/booth2.htm

Klaus