I plan on making a home made paint booth to fit in my garage. It should be pretty straight forward except should it be an up-draft or down-draft booth. Are there any benefits to either?
The down-draft wont be right under the car but probably an exhasut port in each corner as low as possiple and filters at the top of the booth. If it were to be an up-draft I would probably utilize one large exhaust opening right above the car and filters in the corners. What I am most concerned about is any effect on the paint job itself, I am using an HVLP setup.

why not a cross draft design? I would keep the airflow low and slow and wear a fresh air system. Run the fan for an hour or so before you paint to pull any unseen contaminants/dust are there out before you paint. Pulling the airflow upwards or downwards without good filtration is asking for trouble-every horizontal panel will be littered.

The neat way to do it would be to create a positive pressure inside the booth with air ducted in from a furnace (warm). A positive pressure inside the boothforces dirt out from door jams not suched in by a negative pressue inside a booth. The exhaust should have the filtration to remove particulate before dumping it into the neighborhood and also to creat the positive pressure. I've been noodling one of these for a while and wonder if a few (4,5,6?) lengths of 4" PVC pipe laying on the floor run outside the room to a box with your filtration in it would be adequate. The advantage to a downdraft booth with the exhaust under the car is that all the phnee that falls off/out of the car goes down and out, not swirled around in the booth and into your new paint.

Of course, you don't want to use "combustion" air from a furnace....maybe just air that has been warmed by a furnace. ;)

I have done a few paint jobs in my garage and never did any more than put a sizable box fan in the window at the back of the garage to keep air flowing through. In my case, I have one bay partitioned off as a tool/shop area. I will open that door about four - six inches for incoming draft and allow the fan tp pull the air through the garage. My basic airflow pattern is front to back. The best way to deal with dust or foreign matter is simpley to clean out the garage well ahead and wash it down. Spider webs in the corners have to go, etc., etc. Get rid if anything laying - it all collects dust. Use a HVLP gun and good painting methods and it is really not that hard to get good results. A lot of the contamintion in finished paint is clothing dust.

Lets keep these ideas flowing.
I'd like to see some pics of the DIU paint booth.
What is the recommended paint gun?

Probably too small but a crappy paint booth can be worse then just doing it in the drive under a canopy.

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=42211

Don't make fun of the canopy idea. Actually that is a good idea. As long as the prevailing side is sealed, it is basically a closed structure. The biggest obstruction in a garage is the dust. I know a couple of guys around here that will paint a car outside on a good day.

I've seen enamel jobs done in dirt floor garages years ago that actually turned out really well, wet the dirt and lay down some plastic smile.gif The key to doing a good job without much contamination is to control your air movement-you want the air to be flowing well enough to remove the evaporating fumes and some of the overspray but not so powerfull it picks up every piece of dirt in the county and lays it on the car. There is a careful balance, some of the heated downdraft booths I've sprayed in were adjusted for slightly positive pressure but they flow a very large volume of air. A good friend of mine makes a temporary spray area in his home garage for every car he paints-he uses regular masking plastic and swears the static on the plastic actually draws contaminant particles away from the car. Some of the best paint jobs in the world have been done without a professional spraybooth-ever see Gene Winfield's garage? A nice booth just makes it easier and definately healthier.

Get a fresh air sytem to breath ie Hobbyair2 and a good shootsuit ie..a moonsuit and screw the air/dirt movment froma fan until it has tacked up! smile.gif