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Spray Finishing Tips
By Steve Maxwell
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If you're like most do-it-yourselfers, you probably haven’t had much experience spray-finishing wood. That’s because the process has traditionally required expensive tools and a well-equipped working space. But spray finishing in the home workshop is now more convenient than ever for two significant reasons.
First, you can now buy reasonably priced spray equipment made for serious home use. These high-volume, low-pressure (HVLP) sprayers produce less air-clouding over-spray than traditional compressor-driven equipment, making it practical to set up a spray area in any small shop.
The second reason it all makes sense is the wide availability of waterbased urethane. It’s low-odour formulation greatly reduces the kind of industrial-strength, mechanical ventilation needed to spray lacquer or oil-based products safely.
But for these two advances to be any good, you’ve got to realize that spray finishing is an entirely different process than working with a brush. Be prepared to make mistakes the first time you point a spray gun at a piece of wood, and keep these tips in mind for shortening your learning curve:
Tip #1. Keep the Spray Gun Moving
Always release the spray trigger at the end of each pass, then press it again only after your arm starts moving back. Since there is a constant stream of finishing material flowing out of the nozzle as the trigger is pulled, you need to keep the spray gun moving. This is easy when you're in mid-stroke and spraying along an expanse of wood, but trickier when you arrive at the end of your arm stroke and must stop and reverse. That pause is long enough to cause over-application if you keep the trigger pulled.
Tip #2. Spray Only Horizontal Surfaces Whenever Possible
Even if it seems to slow you down, coat items as they lie flat. This applies to both brush and spray applications, but is especially important when you're using a sprayer. Two-inch-long finishing nails hammered every 6" through 3/4"-thick wooden strips make a great support base for finishing. Those little plastic pizza spacers that keep the cardboard carton from drooping down into your melted cheese are great for supporting small items.
Tip #3. Use Light, Multiple Coats
Apply each coat just a little heavier than a mist. Multiple thin coats are much better than a few thick ones. When you're watching that spray stream fan out from the tip of your gun, coating your project in a wet, glistening skin, there's a powerful temptation to lay it on thick. Don’t secumb. Not only will you promote runs, but a thick finish won’t dry well and could even turn into a bubbly mess.
Tip#4. Lighting is Crucial
Use a powerful portable light (I have three 500-watt quartz-halogen spotlights in my shop) to illuminate your work from a point just a bit higher than the workpiece. Ordinary overhead lighting just doesn't cut it. Be prepared to move the light as needed during spraying.
Spray finishing without an angled beam of light bouncing off the workpiece is almost as bad as spraying in the dark. Angled light is important because it allows you to see exactly where you've sprayed, where you haven't, where you're in danger of over-application, and where a run has actually occurred.
Tip#5: Always Carry a Brush
Chances are good that, despite your best efforts, runs will develop on your work now and then. I keep a 2-inch wide brush handy whenever
I’m spraying so I can work these runs out as they occur. Runs never happen instantly, but usually develop several minutes after application. Check newly sprayed work after a minute, looking for trouble. The sooner you brush out runs the better. But don't try to brush out a run that has started to dry, since this will leave indelible brush strokes. Sand it level when dry, then cover it again with another coat.
Do al this right, and you’ll find spray-finishing an excellent and practical way to creating shimmering wood in less time than it takes with a brush.
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Spray Finishing Tips
By Steve Maxwell
|
|
|
If you're like most do-it-yourselfers, you probably haven’t had much experience spray-finishing wood. That’s because the process has traditionally required expensive tools and a well-equipped working space. But spray finishing in the home workshop is now more convenient than ever for two significant reasons.
First, you can now buy reasonably priced spray equipment made for serious home use. These high-volume, low-pressure (HVLP) sprayers produce less air-clouding over-spray than traditional compressor-driven equipment, making it practical to set up a spray area in any small shop.
The second reason it all makes sense is the wide availability of waterbased urethane. It’s low-odour formulation greatly reduces the kind of industrial-strength, mechanical ventilation needed to spray lacquer or oil-based products safely.
But for these two advances to be any good, you’ve got to realize that spray finishing is an entirely different process than working with a brush. Be prepared to make mistakes the first time you point a spray gun at a piece of wood, and keep these tips in mind for shortening your learning curve:
Tip #1. Keep the Spray Gun Moving
Always release the spray trigger at the end of each pass, then press it again only after your arm starts moving back. Since there is a constant stream of finishing material flowing out of the nozzle as the trigger is pulled, you need to keep the spray gun moving. This is easy when you're in mid-stroke and spraying along an expanse of wood, but trickier when you arrive at the end of your arm stroke and must stop and reverse. That pause is long enough to cause over-application if you keep the trigger pulled.
Tip #2. Spray Only Horizontal Surfaces Whenever Possible
Even if it seems to slow you down, coat items as they lie flat. This applies to both brush and spray applications, but is especially important when you're using a sprayer. Two-inch-long finishing nails hammered every 6" through 3/4"-thick wooden strips make a great support base for finishing. Those little plastic pizza spacers that keep the cardboard carton from drooping down into your melted cheese are great for supporting small items.
Tip #3. Use Light, Multiple Coats
Apply each coat just a little heavier than a mist. Multiple thin coats are much better than a few thick ones. When you're watching that spray stream fan out from the tip of your gun, coating your project in a wet, glistening skin, there's a powerful temptation to lay it on thick. Don’t secumb. Not only will you promote runs, but a thick finish won’t dry well and could even turn into a bubbly mess.
Tip#4. Lighting is Crucial
Use a powerful portable light (I have three 500-watt quartz-halogen spotlights in my shop) to illuminate your work from a point just a bit higher than the workpiece. Ordinary overhead lighting just doesn't cut it. Be prepared to move the light as needed during spraying.
Spray finishing without an angled beam of light bouncing off the workpiece is almost as bad as spraying in the dark. Angled light is important because it allows you to see exactly where you've sprayed, where you haven't, where you're in danger of over-application, and where a run has actually occurred.
Tip#5: Always Carry a Brush
Chances are good that, despite your best efforts, runs will develop on your work now and then. I keep a 2-inch wide brush handy whenever
I’m spraying so I can work these runs out as they occur. Runs never happen instantly, but usually develop several minutes after application. Check newly sprayed work after a minute, looking for trouble. The sooner you brush out runs the better. But don't try to brush out a run that has started to dry, since this will leave indelible brush strokes. Sand it level when dry, then cover it again with another coat.
Do al this right, and you’ll find spray-finishing an excellent and practical way to creating shimmering wood in less time than it takes with a brush.
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