Spray Booths Made Simple

Transcription

1 Spray Booths Made Simple Two safe solutios for small shops By Michael Dresder Y ou probably already kow this, but if you spray fiish, whether it s a waterbased fiish from a HVLP rig, lacquer from a compressor ad gu, or eve pait from a aerosol ca, you eed a booth. I additio to the obvious health ad safety reasos, usig a booth ca result i a better lookig fiish by helpig to prevet 44 woodcraftmagazie.com atomized overspray from settlig o your work. The problem is that few of us ca afford a commercial system that meets every health ad safety requiremet. Because of this, may woodworkers wait aroud for the perfect day to spray outside the wrestle with bugs ad blowback, or simply igore the rules ad spray idoors. Aug/Sept 2010 A third optio is to build your ow booth. The key is to realize that a booth does ot have to be elaborate or expesive. Here s what you eed to kow about spray booths, icludig two setups that you ca costruct from materials you might already have i your shop. At the ed of this story, you wo t have ay excuses for ot usig a spray booth.

2 Figure 1: Basic Spray Setup Exhausted air ad fumes Bechtop Booth Fresh air Garage door opeig Full-Sized Booth Door Use heated idoor air whe sprayig durig witer moths. Close widow to ecourage airflow from behid booth. Use outdoor air whe sprayig i warmer moths. Opeig a widow or door behid the operator helps establish the airflow eeded to safely direct fumes ad overspray outdoors. Spray booth basics I its simplest form, a spray booth is a fuel desiged to move air through a small opeig. A fa sits at the small ed of the fuel to direct the fiish lade air out of the room. Because you ad your project take up a lot more air space tha the small surface of the fa, it s ecessary to istall baffles aroud the fa to move air more efficietly. Whe sprayig, your goal is to stad i (ad breathe) clea air while directig atomized fiish toward your project (see Figure 1). You also wat the overspray (fiish that does ot lad o the work) to go outside where it caot be ihaled by you or settle o your project or other objects i the room. As a side beefit, air movig across your work will help dry the fiish more quickly. The fuel is oly half of the equatio. I order for the booth to work, you eed to supply it with as much makeup air comig ito the room as is goig out through the fa. Durig the summer moths, you ca supply plety of makeup air simply by opeig a widow or a door. A scree should prevet bugs ad dadelio fluff from becomig part of your fiish, but whe the polle cout rises, I recommed coverig the opeig with a furace filter. Witer is aother story etirely. Whe exposed to frigid coditios, most fiishes ca get pretty persickety. For home shops, you ca steal heated air from your home, at least for the duratio of a short sprayig sessio. Be sure to crack a widow idoors to let i fresh air. This will result i a small spike i that moth s utility bill, but the makeup air prevets the chace of a egative pressure situatio. You do t wat your dryer, water heater, or other fuel-burig appliaces to vet combustio gases like carbo mooxide back ito your home. About Our Author Michael Dresder is a atioally-kow fiishig expert with over 35 years of experiece. I additio to writig may articles, he is the author of, The New Wood Fiishig Book (1999), ad Wood Fiishig Fixes (2003). Photos: Jaso Gawich; Illustratios: Melaie Powell Aug/Sept 2010 woodcraftmagazie.com 45

3 Figure 2: Bechtop Spray Booth Duct tape Rotate fa to make cotrols easily accessible. 120 Cardboard vaes direct airflow, helpig the fa draw fumes ad overspray outside. Protect your workbech with cardboard or kraft paper. Bechtop booth For sprayig small pieces bowls, boxes, ad the like I suggest makig a simple booth, like the oe show i Photo A, to fit your bech ad closest widow. The booth is simply a iexpesive 20" box fa Use duct tape to attach cardboard vaes to fa. outfitted with cardboard agled vaes attached with duct tape (Figure 2). Whe ot i use, I remove the vaes, fold them up, ad stash them with my sheet goods. Use paiter s tape to attach a stadard 20 20" furace filter Spray Booth? Yes. Explosio-Proof Fa? It Depeds May fiishig articles state that explosioproof fas must be used whe sprayig solvet-based stais ad fiishes. This is soud advice, but the reality is that fa prices start at $400. May cash-strapped hobbyists go boothless ad limit themselves to water-based fiishes, or spray solvets without a fa. Explosio-proof fa or ot, if you spray, you eed a booth. Waterbased fiishes are oflammable, but you should ot be breathig i atomized fiish, or do you wat it settlig o your other work or tools. Sprayig solvets without a booth will quickly fill the room with fumes ad overspray. Ay sparkproducig device, such as a switch, light, or radio, could trigger a solvet explosio. 46 woodcraftmagazie.com Aug/Sept 2010 Furace filter Attach filter to hood with paiter s tape. 18" i frot of the fa. A cheap filter is good eough for capturig most of the wet droplets ad dry particles ad will keep the fa s motor ad blades clea. Be sure to replace fa filters regularly. Dirty filters move air less effectively ad ca cause a fa to bur out. Kowig how woodworkers work, you d expect to read about dozes of fiish-related explosios each year, but you do t. I order for a solvet explosio to occur it must achieve a certai air/ solvet cocetratio. This is referred to as the solvet s lower explosive limit (LEL). As log as the fa is operatig before you start to spray, a basic booth will make it almost impossible to achieve the LEL. Sparks or o sparks, othig will happe. Uder safely cotrolled research coditios, I took a cheap box fa, tured it o ad sprayed pure lacquer thier ad alcohol through it to see if I could achieve igitio. I could t, ad if you do the math for air volumes, it s o surprise. If your goal is safety, you re much better off with a box fa outfitted with simple cardboard walls cardboard tha goig boothless.

4 Figure 3: Large Foldig Booth Top 4 8' cardboard pael Hook ad loop tape 1" 1" 8' wood beam stiffes cardboard top. After sprayig, remove the top, fold up the walls, ad slide it ito your plywood rack. Full-sized foldable booth For larger projects chairs, tables, cabiets you ll eed a bigger booth. My solutio is a three-wiged wall made from a large cardboard box obtaied from a local appliace store (Figure 3). This spray booth is desiged to sit i frot of a ope garage door. The side walls move i or out to fit your project. Hook-ad-loop tape o the lid ad walls help hold the sidewalls i place. Cut the strips log so Filter cloth cover keeps overspray off of fa blades. that you ca adjust the size of the booth to fit the project. With the exceptio of the 1 1" wood support beam attached to the lid, the etire setup is cardboard. Just like the bechtop model, it folds up flat ad slides eatly ito my plywood sheet goods rack for storage. Side 4 6' cardboard pael Move side paels to suit work. A larger booth requires a larger fa. I use a idustrial fa ad keep it shrouded i blue filter cloth. Depedig o the fa, you may choose to positio it o the other side of the back wall ad tape a furace filter over the frot of the opeig, like the bechtop booth. Spi while you spray A turtable makes it easier to rotate the work so that you re always sprayig toward the fa. For my bechtop booth, I use a Paiter s Pyramid fiishig turtable (Woodcraft #150649, $49.99). For my full-size booth, I built a turtable from plywood ad a pair of two-foot log black iro pipes (Figure 4). As luck would have it, 1" pipe just fits ito 1 1 4" pipe. By usig two equal legths of pipe, you create a bearig that is the full legth of the pipe, makig the turtable exceptioally strog ad stable. Add some lithium grease to the bearig surfaces, ad the turtable will spi like a top. I ve sprayed projects weighig as much as 300 pouds without ay problems. Figure 4: Shop Made Turtable 1" pipe flage 1"-dia. threaded black pipe, 2' log 1 1 4" threaded black pipe, 2' log 1 1 4" pipe flage Top 3 4 x 42" dia. plywood Base Plate 3 4 x 18" dia. plywood Base 3 4 x 48" dia. plywood Aug/Sept 2010 woodcraftmagazie.com 47

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