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Latest Article by Bill Perry

Finishing Feature Article by William Perry: Spraying Right, Spraying Safe, Where to Use Your HVLP Sprayer.

 

Now that you’ve bought your spray system, where do you use it?

Okay, you’ve made the move and have purchased an HVLP spray finishing system. But before buying did you give much thought to where you were going to use it?

From talking with my students, I’ve found that the majority believe that with HVLP, they can spray anywhere. While this might be true, the spray finishing environment must still have some controls. If you do not have a formal spray booth, there are options to create a safe and controlled environment.

So what to do? An easy answer is to spray outside but I’ve never found this to be the best solution. Trying to achieve a fine finish when you can’t control the breeze, or dust particles, or insects (which love a fresh film finish)can sometimes be a losing battle and I’ve given up on outdoor spraying entirely.

What’s next? Your garage, if you have one, can work fairly well. So long as you spray during a calm day, you can get away with using a room or box fan to direct airflow (and any minimal overspray) out the open garage door. You can also hangsheets from the garage door tracks, making it smaller.

For a lot of us, though, either the garage is already filled with cars, bikes, lawnmowers, etc., or we don’t have a garage. Then it’s time to confront setting up some kind of room or booth where we can spray without worry. Fortunately there are a few solutions which are both effective and inexpensive.

Painter’s plastic drop cloths are often a first choice for draping and enclosing an area. They tend to be flimsy, however, and billow around with even the slightest air movement. So forget the 1 Mil and 2 Mil stuff. Look for 3.5 Mil plastic sheeting that is used for vapor barriers, covering fiberglass insulation and – paint shields.

Cut the sheet to the dimensions you need and staple the cut pieces to strips of wood – say ¾” x ¾” – which can then be hung from joists in a basement shop or from whatever hooks you might install in the space you have. When you’re done spraying, just roll up the plastic sheets around the wood strips and find a place to store them until needed.

A similar and perhaps better solution is to use tarps. They’re heavy enough to hang straight without blowing around, and have grommets already installed, making it a snap to hang them up. Their only real drawback is that they generally come in black, dark brown, dark green or orange. This will probably require you to have lighting inside your spray area instead of being able to rely on ambient light as you can with clear plastic sheeting.

This is actually a positive feature. Any good finishing area needs to have good lighting, and – ideally – lighting that can be moved around so you have a good view of all sides of your project. It’s also a real advantage to be able to set your lights to give a low, raking light across the surface you’re spraying. This will show up any imperfections immediately so you don’t discover mistakes after the job is finished. Halogen jobsite lights are cheap and do a great job. You will probably have to increase the size of your finishing area a bit to accommodate the lights, but that’s not much of a hardship.

A next step up in creating a finishing area is to use plastic sheeting or tarps, but it is better to attach them to a frame instead of hanging them. A frame can be easily and cheaply put together using electrical PVC conduit. By using the various fittings and connectors available, it’s a simple matter to make several fabric panels that can be used to enclose your spraying area.

Next, have you thought about fumes from organic solvents?

Fortunately, water-borne finishes are becoming better, less expensive, and more widely available than ever, so VOCs (Volatile Organic Compounds) are gradually becoming a thing of the past. Nevertheless, they’re still around. Also, it’s probably not a good idea to breathe anything associated with spray finishes, so air extraction really needs serious attention.

Again, we can start with the simple: A $20 box fan with a furnace filter taped over it does a fair job of extraction so long as you’re not trying to clear a huge area. Its effectiveness drops off drastically the farther away from it you go, though, so it’s best used for smaller projects where the fan can be positioned behind the area being sprayed, catching almost all of the overspray.

You’re much better off if you can position your spray station near a window. That way you really can extract any fumes and overspray and vent them outdoors. If you’re lucky enough to have access to the outside, it’s worthwhile to construct some panels that can be placed on either side of the window, effectively funneling air movement outside.

Sheets of foam house insulation work admirably for this. They can be attached together (and tacked to the floor) with duct tape when you use them, and then stored against a wall when they’re not needed. Position one panel on either side of the window and then place panels on top of these to maximize the amount of air being drawn through your spray setup.

Using this system to vent the air, along with a fan and filter will give you a surprisingly effective spray booth. If you can build a frame to house a fan tightly in the window opening you will kick the efficiency of your system up a few notches more. For a couple of years in a basement shop I had a broken table fan that I could jam into one of the little windows. Some bits of foam insulation and duct tape “sealed” it into place. It worked well enough that I could spray without having any hint of it anywhere else in the house.

Most consumer fans are fairly wimpy however. A higher powered industrial fan will increase the airflow you can achieve many times over. Where to find them? Used machinery dealers are a good place to look, or look for auction notices in the newspaper. You might even find something online with a bit of searching. It’s well worth it if you can find one. Using a 1500 cu. ft./min. fan to extract fumes from my shop a few months ago made me feel like the dude in the Maxell ads, except while he’s being blown away I felt like I was about to be sucked in. (You can take that whichever way you wish.) :–)

There is something which you must remember when selecting a fan: if you will be spraying finishes that use flammable solvents – such as lacquer and lacquer thinner – you absolutely must use an explosion-proof fan. These fans use non-ferrous components and non-sparking impellers rather than brushes and for a very good reason. While various solvents are flammable in liquid form, as soon as they are atomized into a vapor they become explosive. Gasoline is a perfect example of this. It actually has an explosive force greater than dynamite.

How will this affect your choice of area for spraying? If you plan ever to spray finishes which use volatile solvents, you must have a space with absolutely no risk of fire or sparks. Lights, motors and switches must be non-sparking and fireproof. Volatile vapors can quickly fill a room, often sinking towards the floor when they’re heavier than air, and then ignite in a fireball from something so simple as you pulling an electrical plug out of the wall.

This usually rules out your basement as a spray area. It’s filled with switches and outlets, and your furnace and hot water heater are like detonators just waiting to go off.

I must confess that my solution has been to stop spraying finishes which use volatile solvents. And after resisting the move to those nasty, milky-looking finishes for some years, I now find that the new formulas are so far superior to the original waterbased polys that I would never go back.

Without the risk of fire and the danger of working with VOCs, I use spray finishing much more frequently. Some knock-down panels, a fan to direct air flow out the back door and a box fan with filter to catch the worst of the overspray have become my “high tech” solution to creating a spray finishing area. It’s working well; you might want to give it a try yourself.

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