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All,

I'm working on shop renovations and considering adding a small finishing booth capable of spraying Nitro and other flammable finishes. I could use some ideas. Pictures of your setup would also be greatly appreciated.

Also, as an aside, I've recently created a new website. If you have time, check it out and let me know what you think. It's still a work in progress. http://www.jamesleeguitars.com

Thanks,

Aaron

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Aaron Craig

Aaron, if you do a search for my name and small shop you'll find a thread to my shop tour. It looks nothing like that today however I have a small knockdown spray booth which can give you an idea of what can work.

Didn't know it was so easy to search on tapatalk.

viewtopic.php?t=15191#p216647


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"There's really no wrong way, as long as the results are what's desired." Charles Fox

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Here's how one guy did it
http://acousticguitarconstructionforum.com/viewtopic.php?f=33&t=146
Another
http://www.loonsong.ca/page21.html
Don't have any pics of mine yet, but it's just basically a cuboid, 800 x 750 x 700 mm high, squarish funnel inside leading down to a 6" pipe and then though duct hose to an exhaust fan. (I like the idea of spaying downwards)

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

What's small? Mine is 10x16. In it is a sink, 2'x4' metal rack with 5 racks. It's full. Shelf with hangers for guns. PVC air line to the shop with an in line water trap just before the gun. Use about a 6' hose from the trap to guns. Explosion proof fan. I think it's about 750 cfm. Maybe more. It's been a while since I put it in. I have a stand on wheels for about 36 cabinet doors and drawer fronts. And my buffer lives in there. It works well.

So, let's see... It's bigger than most amateur's entire shops there's no pictures or links.
Hmmm

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Almost as big as my shop but I don't do cabinets anymore either. My booth is 5' X 7'. I have an explosion proof fan that vents to the roof, a StewMac holder for the guitars, and a drying cabinet for two guitars.

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Steve Smith
"Music is what feelings sound like"

Hope that drying cabinet is fan vented to the outside.
ANY time you can smell the lacquer, you are killing yourself. Offgassing lacquer is just as bad as sticking your head in the can.

Not vented. When I sprayed nitro I had to wear a respirator when I came back in the shop. Mostly I just stayed out for a week or two. Recently I've been spraying other products such as Royal Lac that will let me get back in the shop sooner.

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Steve Smith
"Music is what feelings sound like"

Thanks all. Collin, I like that first example. I think I will be going with something in that vein. The shop is in our basement with the central air and water heater in the next room, so I'm probably spraying waterborne finishes and other less volatile finishes. I'll farm out any nitro or poly work.

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Aaron Craig

Doesn't get much simpler than this - a hole in the wall with a giant fan! This is at the cabinet making shop I work in. We don't have a separate spray booth, but this allows us to spray inside when it's raining. We usually have the doors open and wear masks until the smell goes away.

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"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

That is not a TEFC motor and could create a spark.

Well it's been in use almost every day for 5 years and hasn't caused any problems. Like I said, we keep the doors open and the fumes don't build up that much.

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"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

You've been very lucky every day for 5 years

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Say what you do, Do what you say.

When it comes to spraying finish, particularly nitrocellulose lacquer, I think you should either go full tilt on safety or don't spray at all. There is this concept in the law known as Assumption of the Risk . . .

A TEFC motor and an aluminum fan blade is not that much more expensive. A couple of hundred bucks to protect against an explosion is pretty cheap insurance.

It's not my workshop, I've only worked there a year so it's not my decision to make. But when it comes to fire hazards, the spark from a fan is the least we'd have to think about. In the winter we have several big radiation heaters going and other people are often using other power tools at the same time in other parts of the workshop, so simply using a spark proof fan wouldn't help anything. We don't have the space for a separate spray booth as we're often spraying large items of furniture, 12ft dining tables for example. A spray booth big enough for that would take up half the workshop, so instead we rely on open spaces and lots of ventilation so the fumes don't build up to a dangerous level.
We only do satin and semi-gloss finishes, so dust isn't much of an issue.

Edit: Just seen you said your shop was in a basement. That's a whole different scenario and I would definitely think more seriously about safety.

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"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

I've been very lucky for over 30 years.

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It will probably be alright.

I am planning a similar spray booth. My question is what cfm is the fan rated at and does it evacuate enough of the fumes considering there is no door to the spray booth? My shop has a convection heater (using outside air) and also an air compressor that could all be ignition sources. I don't want to put a large positive air inlet into the shop because of heat loss & humidification concerns. Any suggestions?

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Btw I like your use of the lazy Susan base on the Stew mac holder. Great idea!

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Explosions are not the only things to worry about. Exposure to the finishes and solvents can mess with your health. if you can smell it, it is working its magic on you, a little at a time.

But I'm not the first person to say this stuff to the folks who rig up these less than ideal spray areas. That's why I mentioned Assumption of the Risk.

I'm using a Dayton 12" Explosion proof fan and the CFM ranges from 600 to 1300 depending on the static pressure of your exhaust ducting - mine is about 12' of 12" flex duct so I'm probably closer to 600 CFM. I crack a window in the shop about 1 1/2" when I spray to provide some makeup air and it doesn't seem to affect the humidity or temp very much. Having a door on the spray booth would be better than open. I normally spray up to four coats per session (depending on the finish) at intervals and I keep my respirator on all of the time. I do spray nitro but the outgassing makes my shop a no work zone for a week or so. I much prefer to work with waterbornes or shellac which will allow me to work in the shop in just a few hours. This is just representative of the spray booth as it is now and there are several things I would like to do to it. One is to add a heavy curtain or even some bi-fold doors to help better contain the atomized mist and maybe allow me to remove my mask between coats. Second is to put in a power vent of some kind on my drying cabinet so out-gassing fumes would go out of the shop.

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Steve Smith
"Music is what feelings sound like"

Some things you night want to consider:

I built my knockdown booth when I was in New Zealand and did a fair bit of research beforehand. One thing I concluded is that, in most jurisdictions, small builders/repairers will find in prohibitively expensive to comply fully with local workplace health and safety codes. You may not even be able to handle some finish materials legally in a residential area! You first need to consider if you're prepared to violate codes.

I consulted the engineer at an industrial fan supply company. I purchased a 16" flame/explosion proof fan that was bloody expensive, but is still technically under-spec for a booth large enough for a person + 1 guitar.

The booth has a 2-foot wide end wall with the fan mounted between it and an opening in the shop outer wall (a window with glass unit removed). There is a round baffle held 6" in front of the booth opening to accelerate flow from the sides. The booth sides are 4-foot wide panels that attach to the end panel with door hinges. There is a top panel and I use poly sheet as a temporary floor. All panels are 1/4 MDF with light 2x2 framing, and stack along a wall when not in use.

Make up air is essential for an exhaust fan to be effective and the opening for the static intake must be at least 4x larger area than the fan -- i.e., an open door. Filters aren't really necessary and simply reduce flow. Set up in both New Zealand and Kenya, this set up was effective and convenient any month of the year, but now here in Quebec, I don't think I will try to spray during the dead of winter -- I would either empty the heated air from my house in no time or freeze in my shop with an open outside door for makeup air!

No, not ideal and likely violates code, but i don't have any employees. If used sensibly, my setup should at least keep me and my family safe.


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Good points Tim and one of the reasons I'm trying to avoid nitro to move towards safer finishes. Where I live there isn't much in the way of regulation if you're a one-man operation so that's not much of an issue.

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Steve Smith
"Music is what feelings sound like"

After spraying nitro with my big fan I hang a box fan on the booth to exhaust the off-gas for the following week. Makes a big difference.

Here's my portable spraying booth for nitro.
Fully open, so no cloud of overspray lingering around.
Lightweight, cheap, and a work of art.
I take it outside before using.

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