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I am starting to think about making a spray booth so I can explore finishes other than oil, mostly interested in water-based lacquer but I would like to try nitro eventually as well.

My first question is about space. There is only one place in my shop I could put one, a corner with a window three and a half feet away. So would a booth like 3 1/2 x 4 feet be viable? It sounds as if it would be a tight squeeze.

Second question is, what am I looking at approximately for cost of equipment? I take it the fan would not have to be very big for such a small volume but I imagine any size of explosion proof fan is not cheap. I have no idea where you buy these.

What else would I need (other than spray equipment)? I would probably put a clear ceiling in with standard lighting overhead if thats viable.

Thanks

Edward,

Search the archives - Rod True had some pics of his shop and in particular his spray booth set up. His is booth is in the corner of his shop and it's pretty compact. I'm sure if you PM'd him he be happy to share specs.

Rick

Had a quick look for you - here it is http://www.luthiersforum.com/forum/viewtopic.php?f=10102&t=15191&p=216647&hilit=spray+booth#p216647

Hey Edward,

If you want an area dedicated for spraying, i'd say that 3-1/2x4 is too small. You'll end up bumping your guitar into a wall at some point.

Thanks Rick for the link to my shop. My booth area when set up is 6x4 and it's very small. I can get the job done but I have to be careful. If I could, i'd like it to be 6x6 at minimum.

Anyway, if you can make swing out door like I've got, you can make a bigger space for when you spray and still retain much of the floor space when you're not using the booth.

As to the fan, if you're going to explore nitro or poly, you really should get an explosion proof fan. They are not cheap! Acklands has them. You could also check out a farm supply company as they sell explosion proof fans too. Chicken barns need explosion proof fans. You might try Princess Auto too. The clear ceiling is a good idea as long as you keep the lighting behind the ceiling and not in the booth. You want everything to be explosion proof of isolated from the fumes.

When I was looking at explosion proof fans, I found that most started around the $600-800 range. I was lucky in that my Brother in law had one in the house he bought so I got it for a case of beer (I got to share the beer too ).

Setting up for explosion proof is expensive.

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I think positive pressure is the way to go. The fan blows in to the booth. That way it is never in a flammable airstream, and shouldn't need to be explosion proof. Also, you need only filter the one point of intake to keep your booth air clean (you should still filter your main outlet area as well). Leakage in the booth spills this filtered air out, instead of sucking unfiltered air in and being a source of contamination. I don't really know why all booths aren't done this way. I've read that this method is more prone to air turbulence in the booth that can disturb one's spraying, but that seems like a problem worth dealing with versus needing a $900 fan.

Peace,
Sanaka

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...imagine there were no hypothetical situations...

Hmmm.. lots to consider.

Does anyone actually use positive pressure in their spray booth? That seems like a good idea.

My biggest problem is the layout of my shop, its all very awkward when trying to add a booth. If the window was not so close to that corner it would be no problem to have a 6x6 booth in that area. Maybe just have the booth a foot away or so not to cover the window? The problem then would be that the only wall it would be adjacent to is an interior wall, so I would have to put some sort of passage over to the exterior wall for venting.

My only concern with positive pressure is that if the spray booth is not sealed then a portion of what you want to be exhausted outside is going to end up in the shop. My plan is to bite the bullet and get an explosion proof fan.

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I spray booth would be nice but I don't have the luxury of space in my microscopic work area. I spray with water based and just do it outside on a clear, warm day. It works well in So Cal.

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Edward,

Have you seen this one: http://www.highlandwoodworking.com/knoc ... booth.aspx.

I fashioned something similar for use in my shop. I use water-based lacquers, so a $150 fan from Global Inc pulls air through filters and out into my shop. I have an overhead filter I run while spraying. I still get more dust in the shop during the winter than I'd like, but the setup helps. During the summer, I open the garage door and have the fan pull the air out of the garage.

Ken

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Sealing adequately isn't too hard. I made a temporary positive pressure "booth" out of a kitchen whose cabinets I refinished with ultra-nasty catalyzed automotive finishes. It was an intensive masking job, but amounted to just tape and plastic dropcloths to seal it from the rest of the house, a fan feeding one end, a duct to outside on the other end. Some odor escaped into the house and I kept the owners away while I was spraying, but there was no overspray residue outside the kitchen (the fact that I didn't use adequate respirator equipment inside the spray area and ended up bedridden for a day is its own little tale of brain damage...). Tweaking a more permanent setup to pretty much eliminate even odor leakage would be quite feasible.

Peace,
Sanaka

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...imagine there were no hypothetical situations...

Positive pressure implies you are in there thus implying a bigger booth. I imagine someone could fashion one of those boxes like they use at the CDC (you insert your hands through gloves in the wall) but that would seem to make the process very difficult. I have a friend who builds experimental (RE: Kit) airplanes and when its time for paint, he builds a temporary booth outside with timbers and plastic and uses positive pressure. Don't forget what you save in the fan, you will spend in the breathing gear.

Mike

By the way, that Dyson vaccum fellow has a neat idea for fans using airfoils to create airflow (Dyson Fan). Airflow may not be great enough. But how cool would that be? Nothing to create a spark, just a circular wing and pressurized air. You could probably power it with a DC motor and impeller.

Mike

Well I think the breathing gear investment should be the same no matter what your spray setup. My above described kitchen scenario didn't exchange air very fast. Something set up in your shop should move lots of air whether it's positive or negative pressure or natural breeze. However, when we atomize liquid at arm's length we are exposed regardless, so respirator gear is the necessary last line of defense. After my kitchen scenario is when I bought a forced air respirator and breathing air filters. I also don't trust that breathing waterborne finish is amazingly less harmful than solvent.

Peace,
Sanaka

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...imagine there were no hypothetical situations...

What I meant us that if you are inside a paint booth, you might need a forced air supply system for breathing. Those are expensive.

Ken, thanks for the link, but I am hoping to do something that allows for volatile finishes as well.

Mike, what does a forced air breathing system cost?

I though I saw a standard style full face respirator in Rod's thread and he goes inside?

I dont think it would be too much of a problem to seal the booth, If it was a 2x4 structure would poly on each side sealed at all seems/fasteners be sufficient? I still would like to hear more about positive pressure. I just dont understand why if it is so feasible more people dont use it?

There are plenty of sites where you can download ideas and plans for spray booths. I like the positive ones but often they can be unealistic in real shop environments. You need lots of filtration to avoid dust contamination . The explosion proof fan is a good design and you can bring in outside air .
There are many parts of this equation to consider. RH Values and climate control. Then can your hvac unit handle the draw. There are some very good small spray booths that are available so you don't have to reinvent the wheel. I know a few guys that have tiny spray booths that are 4 foot square and do excellent work.
This isn't an easy question to answer so educate yourself the best you can . Talk to other builders to see what they have and what they use. I needed the room and took out my booth and now I contract my finish work. To be honest ,that was a great decision as a good finsher can save you time and money.
Be sure you get a good mask . I have 2 of them so I don't have to change the filters in the middle of spray. If I do set up another booth I wil get a pressure mask. I like breathing the fresh air over the filtered. Good luck on your search

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Edward, this link will show you the SAR that I use in my cabinet shop

http://www.sperian.com/Products/Sperian ... ir_(CF-SAR)_AABA_Pumps_and_Systems_(NIOSH).aspx?site=/americas


I purchased one about 10 years ago for about $800....best money I ever spent. At the time I was refinishing furniture and replacing cartridges every 6-8 hours (recomended) in a regular mask. At $25 for cartridges the cost of this system quickly paid for itself. The SAR unit has one dust filter which is replaced every 100 hours at $4. If all you're doing is a few hours here and there it probably wouldn't be worth it.

Paul

Hey Mike, I don't mean to be contentious and maybe there's something I don't get, but I don't feel one type of spray setup demands a forced air breathing system whereas another doesn't. It's all about how much air is moving through whether it's forced in or sucked out. Either way, I'd call a good filter respirator the mandatory minimum and a forced air setup the wise option. At my old cabinet shop job where I was the spray guy for about a year, we had a commercial automotive type booth and just used a filter respirator, as I think is common practice. It seemed fine, but looking back I think forced air should be used even in that setup. One can't help a little daily exposure, and one gets slowly, cumulatively sensitized.

Like PaulK my forced air helmet is probably the best shop investment I've made. I never even thought about recouping the cost against the stream of cartridge filters (probably because I never changed them often enough anyway...) I went with the 3M L-901 full helmet style and fed from my compressor which needs a special filter to produce "grade D" breathing air. This setup cost around $1100 total, a mere blip against potential long term health expenses due to spray exposure.



Unlike a filter mask, this thing is truly absolute in its rejection of outside air. I got the helmet thinking it would be nicer than a mask stuck to my face and this has borne out true. It is actually very comfortable to wear and the visibility is perfect. I forget it is even on. It's great at the lathe too, or anytime you're making lots of hard to capture dust, and doubles as eye protection. The face shield flips up to drink water or even talk on the phone, though you can wear a bluetooth thingy inside and talk hands free.

Well somehow this turned into a commercial for a forced air helmet. I guess I like mine...

Peace,
Sanaka

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...imagine there were no hypothetical situations...

Perhaps you should think of it as a spray "area" rather than a "booth". Open faced spraying is de rigeur in high end environments. For guitar work a simple and cheap $2000 Griz fan and filter unit should suffice.

Perhaps you should think of it as a spray "area" rather than a "booth". Open faced spraying is de rigeur in high end environments. For guitar work a simple and cheap $2000 Griz fan and filter unit should suffice.

Sanaka, no offense taken. It all depends on what is sprayed. I think if I was on the inside of a booth, pos or neg, I would prefer an air supply. Too many times we have seen "accepted" exposure levels prove to be inadequate. Then, it's foo late. I like water bournes, wear a mask yes, but less worry about explosions and exotic chemicals. Some paints are carcinogens, but that is, of course, stretching the point here. Mike Doolin told me that his explosion proof, comercial system cost about $2K. Seems a good way to go.