Positive pressure Spray Booth?

[Jonathan Spool]

I have an area designated for finishing in my new shop. Approximately 8' x 7'.
I will be using only water based finishes.

I have debated between building an actual finishing room, which would theoretically be dust free, and allow me to continue working in the rest of the shop while a projec dried, and putting in a free standing booth, one that was originally designed as a spray booth, or converting a greenhouse kit into a booth.

eceently I have seen posts from finishers that thought that an open front booth is sufficient for wood working, and I pondered a booth that was wall mounted on the exaust side, and had wings that would fold out.

If I would go with an open booth, and the project sat basically in front of the fan while being finished, wouldn't the exaust draw every bit of suspended dust in the rest of the shop directly to my newly sprayed piece? It would seem to me that I would have to keep out of my shop for a day in order to make sure the air was completely clear!

What about a positive pressure system? Anyone made one of these?
I could make the room out of fold away panels, and wouldn't have to worry about it being tight at all, as air will be exiting.

Some feedback and suggestions would be appreciated.
Jonathan

[Kirk Poore]

If you're going to make it positive pressure, where are you going to get the air from? Will you be able to filter the air sufficiently? Would you mind the smell of finish in the rest of the shop?

Would a well sealed area work better?

Kirk

[Ed Hazel]

Real spray booths are positive pressure the ones I have seen have two blowers one in and one out. It took some effort to keep everything working properly.


I would think and enclose area with a good exhaust fan blowing outside with an intake area with a good filter on it should work fine. Most spray booth bring in fresh air from the top and exit out the bottom either via the floor or low on the walls. The trick is not to bring any dust in the spray room via your project or your clothes.

[Peter Aeschliman]

What about setting it up so that the incoming air is blown through an air scrubber... like the one linked below? That way you know the incoming air is clean. You'd also need an open window with a filter on it, or return air vent back into the shop with a filter on it to try and catch some of the finishing particles (don't want over spray blowing out of the booth onto all of your tools.


http://www.amazon.com/708620B-AFS-1000B-Filtration-Electrostatic-Pre-Filter/dp/B00004R9LO/ref=sr_1_1?ie=UTF8&s=hi&qid=1287005914&sr=8-1

[Jamie Buxton]

I spray waterbornes (mostly from Target) in my shop. I don't use a booth. One of the nice things about finishes designed for spray application is that they cure very quickly. The ones from Target cure to tack-free in five minutes or less. That is, the time window when junk can land on them is very short, so the finish rarely has embedded junk in it.

[Tom Ewell]

I agree with Jamie, I would set up a booth only to control vapor and for slow drying finishes.

I also use Target products and as long as the dust is settled within the shop, little to no "junk" gets into the finish. (I do vacuum the finishing area and have air filtration in the shop)

Most overspray dries before it hits the floor, no worse than fine dust put out by wood working tools so spray goo on the machinery is negligible and easy to vac or wipe off if one is irritated by such things.

Respirator is a good idea too (I use an Aircap2)

[Jonathan Spool]

Naturally, a dedicated room, completely sealed off from a dusty environment would be best. I could build that, but I would lose the versatility of the space involved. I thought about an open booth, but didn't like the idea of the exaust pulling contaminated air over my project.
In any positive pressure booth, the input air is filtered well, as is the exaust air, but if I vent into the shop, fumes could be an issue, albeit not as much as I will only be using water based finishes. I have been lax on my finishing skills and efforts, an results for many years, and want to get to the point where I can lay down a good finish, dust free, and still have the ability to continue to work in the shop on other projects.

[Jim Tobias]

I'm with Jamie and Tom also. I went to a lot of trouble to put together a booth out of 4 mil plastic and used pvc for support, etc, etc. Put in a fan on one side and had filters in wall on other side. Even bought a shoot suit and put i ton. I had a lot more issues with getting flecks of dust etc. on that project than any other. In my case, it seemed the moving air and the dust on my body was being circulated and causing more problems. Never again!
I just finished spraying a chest of drawers and a desk in the shop and the only thing I did was: 1) cover the floor in brown paper 2) stand up some tall cardboard as a back drop on 3 side so I wouldn't spray directly on other stuff.
The finish is dead smooth with no visible contamination.
I do use Target finishes(fast drying) and have an air cleaner(JDS). I always go into the shop and spray as soon as possible before I have stirred up much dust.

my $.02

Jim

[Jonathan Spool]

Well Ok then! I guess my best course of action is to experience some finishing in the new shop with no fans blowing, and hopefully get as good results as you guys have been getting. Thanks much for the input. Real life experience usually trumps inexperienced logic!

[Tom Hoffman]

I had enough space, so I partitioned off a 10x12 room that has one outside wall in which I installed a window. On the opposite wall is the door and an attic fan (in the wall) that blows into the room taking air from the shop through 2 furnace filters. I open the window, turn on the fan (wired outside the room), and wait about 30 minutes before spraying. There are no lights, no electricity in the room, but I did install a solar tube light through the roof. During the day the solar tube and window light is sufficient. Any overspray gets blown out the window. All surfaces are paneled with OSB. I've successfully sprayed oil based lacquer, varnish, and shellac; and water based products. Even with slow drying varnish, I've had no problems with dust nibs. The fast drying lacquer gives an awesome finish! After I got all this work done and experimented a bit, I feel like I've reached finishing nirvana.