The most common method of staining is to apply a wet coat and wipe off all or most of the excess before the stain dries. Any application tool can be used to apply the stain – rag, brush or spray gun, or you can dip, then wipe.
A less common method of applying stain is to spray it on the wood and leave it. By not wiping, three major goals can be accomplished:
- A more even coloring on tight-grained blotchy woods, such as cherry, birch, maple and pine
- An even background coloring on all woods
- Bring the color of sapwood (or lighter woods) closer to that of the heartwood
The stains used for this technique are called spray/no-wipe stains.
By spraying a stain and not wiping off the excess, you’re applying an even amount of colorant everywhere. So blotching in tight-grained woods is almost totally eliminated. But, by not wiping off the excess you also reduce, and even eliminate, grain definition. It’s the wiping off that leaves more colorant in the grain and blotchy areas.
If you are achieving your entire color development with just no-wipe stains, you’ll find that they are most advantageous on tight-grained woods that tend to blotch. But they wash out the grain on open-grained woods.
To achieve both grain definition and an even background coloring on open-grained woods, apply a washcoat over the no-wipe stain, then apply a wiping stain and wipe off the excess. This will leave colorant in the grain, which will highlight it.
Pigment and dye
When selecting a stain, it’s important to be familiar with the two types of colorants: pigment and dye. Pigment is solid particles of color that settle to the bottom of the can and have to be stirred into suspension. Dye dissolves in the solvent (or water) and doesn’t settle.
Pigment is the more difficult colorant to use as a spray/no-wipe stain because it can muddy the wood if too much is applied. Dye produces more clarity. Some commercial no-wipe stains contain both.
Modern grinding technology has made it possible to grind pigment so fine that it performs a lot like dye. If you are buying no-wipe stains from a commercial supplier, you should be able to get a near-dye look using pigment.
The advantage of pigment over dye is that it fades much less. All dyes fade in direct sunlight, even through a window, no matter what the claim of the manufacturer. Some dyes just fade less rapidly. But on objects made to last years, the only way to avoid fading is to keep them out of direct sunlight.
Any stain can be made into a spray/no-wipe stain by thinning it. Even stains sold as no-wipe stains can be thinned more for better control. The trick is to thin the stain enough so you build the color with multiple passes. If you try to get the desired color with too few passes, you’ll get uneven streaking.
Also relevant when thinning a stain is choosing a thinner to get an optimum drying rate. If the stain is drying too slowly, it may mottle – bunch up into thicker spots and ridges. If it’s drying too rapidly, the stain will be difficult to apply evenly without overlaps.
You can use any type of spray system to apply spray/no-wipe stains, but it’s much easier to get even results with the soft spray of HVLP. Airless and air-assisted airless can also be used. If you use a conventional spray gun, spray at a distance with a very wide pattern.
No matter which type spray system you use, it’s critical that the gun be clean and adjusted properly. You should be getting an even spray across the width of the pattern. If the pattern is heavy in the middle or at the edges, it won’t be possible to keep the coloring even. You’ll get streaking.
There are a number of considerations and techniques to be aware of for getting good results with no-wipe stains. These include hand, arm and body motion; overlapping and box coating.
The body motion you use in applying no-wipe stains is the same as you should be using with all your spraying. Lock your wrist, elbow, arm and shoulder, then walk the width of the object you’re spraying with even steps while holding the gun at the same distance throughout.
Don’t wave the gun or swing it back and forth. Keep the spray pattern as consistent as possible throughout.
Overlaps can cause darker areas and streaking. To avoid this, overlap each pass by 50 percent. Begin and end each pass several inches off the target object. The first pass should be half on the object and half off. Then overlap each pass by 50 percent until you have covered the entire area. Finally, make the last pass half on and half off.
To further reduce the possibility of streaks, use the box-coat method of spraying. Alternate your passes between horizontal and vertical, or one way then 90 degrees the opposite way after completing each coverage. Box coating helps eliminate streaking caused by overlaps (essentially by disguising the overlaps that do occur).
If you are finishing more than one object, or a very large object, prepare a step panel so you know when you have reached your target color. A step panel is either a single panel with the target color for that step, or it is a panel divided into sections with each color step in its own section.
Stains lighten in color as they dry. Because of the method of spraying, no-wipe stains lighten rapidly. So at some point you may need to spray a washcoat to lock in the color and see what you have. If the washcoated color isn’t dark enough, you can spray more no-wipe stain on top. At this point the no-wipe stain technically becomes a toner.
Raised-panel doors and other three-dimensional objects can be difficult to spray to an even color because of the recesses in the profiles. Instead of trying to spray these profiles at angles, as you might do with a finish, spray the object as flat, holding the spray gun at an even distance while moving back and forth and overlapping 50 percent.
Then insert a glaze step, called fill glazing, into your finishing procedure to bring the coloring of the recesses even with the flats. After a washcoat, or in between coats of finish, apply a glaze of the same color as the no-wipe stain to these recesses.
Spraying no-wipe stains successfully requires practice. It’s the reason most finishers would rather use wiping stains. But more elegant, sophisticated and richer results can be achieved with no-wipe stains, so the practice pays off.
Bob Flexner is author of “Understanding Wood Finishing” and “Flexner on Finishing.”
This article originally appeared in the September 2015 issue.