If you intend to spray any volatile liquids in your shop, you should consider setting up a spray booth or a room for this operation. The spray booth will safely carry away any dangerous fumes from the spraying operation and thus minimize the explosion hazard that a spraying operation carries with it.
Spray Booth Size:
The size of the spray booth has much to do with the product you intend to finish. If it is a large acoustic guitar for instance, then you should size the booth so you can maneuver the guitar in different positions without worry of hitting a wall, door or cabinet.
When I am spraying, I do not choose to lay the guitar on a flat surface. I know some people do that, but it prolongs the spraying operation for me. I prefer to hold the guitar mainly by the neck and rotate it to spray each surface. I then hang the guitar on a hook, by one of the tuner holes and finish up the neck.
To complete the spraying operation in this manner takes an area of about 5 feet x 7 feet. I have a counter with storage beneath for the volitile liquid storage at one end of the room, and it serves as a small work area if needed. If you axe the counter, you should have a work area of about 5 x 5 feet.
When you are spraying lacquers, varnish or any other volatile substances, you are producing extremely flammable over-spray that needs to be addressed. Any little spark that is created from an exhaust fan, light, or light switch can and will ignite this air-borne spray.
Therefore you should make sure to equip the booth with an explosion-proof exhaust fan and light fixtures. To be save, keep the switches for all electrical devices outside of the room. Do not place any convenience outlets inside the room unless absolutely necessary, and if you do they need to be explosion proof as well.
If you decide to use a high pressure spray system with a compressor, keep the compressor outside the room and hard-pipe an air line into the room to your valve assembly. You can then use a quick connect hose to the air outlet.
If you decide to use a HVLP (High Volume Low Pressure) type of spray setup, keep the turbine unit outside the room as well, just to be safe. These units are often set up with long air hoses that can be fed the the wall and into the room. Just be sure to leave enough slack in the air hose to move around freely. I would recommend that you feed the hoses into the room so they are at your back when spraying. This minimizes the problem of the air being constantly in the way of the spraying operations.
Keep The Spray Booth Squeaky Clean
Dust is a big problem when you are spraying lacquer. Even though the set to dry time of lacquer is rather fast, there can be a few specs of dust that will find their way onto your guitar finish.
Therefore, design the room so you can easily wipe it down after you spray and prior to starting a spraying operation. Also is you go with a rather high volume fan, this will take away most any dust problem.
If you use painted gypsum board for walls and ceilings, use a gloss epoxy finish on the walls. This will permit you to vigorously clean these surfaces if needed. Another option is to use an FRP board, which is a Fiberglas reinforced panel. This product is easy to install and is very easy to keep clean. It is used in food preparation areas that needs to pass health inspections for cleanliness. If you decide to use FRP, do not use any volatile compounds to clean it as you will melt the finish coat. Use only water-base product.
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