The obvious cause of glue squeeze-out in joints is that too much glue has been applied. So the obvious way to avoid the squeeze-out and resulting splotching under a stain or finish is to apply less glue.
But you don’t want to apply too little glue either or you won’t get a good bond. So here’s a trick to give you a little leeway.
As shown in the accompanying picture, you can countersink a mortise and a dowel hole to create a reservoir for excess glue to collect. You can also chamfer the ends of tenons and dowels. Most dowels are manufactured with the ends already chamfered.
Another precaution you can take is to cut the mortise a little deeper than needed to allow excess glue to collect and drill the dowel hole a little deeper than needed for the dowel.
Unfortunately, there’s no easy equivalent for stick-and-cope joints on cabinet doors.
There are two critical elements that make for a great finish – selecting the right brush, and using the right technique. Practice counts as well. You don’t expect to cut perfect dovetails the first time round, nor should you expect to achieve a perfect finish without practicing your finishing technique. I frequently choose brushing because I have a small shop and brush clean-up is fairly quick.
Most of my finishing is done with shellac or varnish. Occasionally I’ll use a water-based finish for light-coloured woods when I want a super clear finish. However, I’ve never used lacquer, so my comments won’t apply to this type of finish.
The most important part of a brush are its filaments (aka ‘bristles’ or ‘hairs’). It’s the filaments, along with your brushing technique, that will have the greatest impact on the quality of your finish. With proper care brushes will last for years, so save yourself a lot of frustration by using quality brushes right from the start, and keeping the brushes in top condition. Cheap brushes will invariably result in cheap looking finishes.
The shape of the brush tip is also important. Avoid brushes that are trimmed flush across the end. A chisel tip will give you much better performance.
Basically, there are three kinds of filaments used in brushes – natural (usually hog bristle, ox hair, or badger hair), synthetic (made from polyester or nylon), and natural/synthetic blends. The general consensus is to choose natural brushes for shellac and varnish, and synthetic for water-based. However I’ve had good success using natural/synthetic brushes and synthetic brushes with shellac and varnish when I thin the finish by 10% to 20% with its solvent.
Natural brushes work well on shellac and varnish because they carry more finish (i.e. to ‘load’ the brush), than synthetic brushes, so that you can lay on more finish with each brush stroke, and maintain a wet edge as you work. When buying a natural brush, look for filaments that have flagged ends – a split at the end of each individual filament. The flagged ends enable the brush to hold more finish and release it with minimal brush marks.
There are two general types of natural brushes. The most common are made from the hair of hogs, typically referred to as ‘bristle’, or ‘China bristle’. Any brush that’s labelled ‘bristle’ is going to be made of hog hair. Hog hairs have naturally split ends. They also taper from the base to the tip, which makes the hair strong yet gives it a lot of spring, so that it maintains its shape in use.
Higher quality natural brushes are made from ox or badger hair, which is a softer, finer, and more pliable filament than ox bristle. You pay a premium for ox or badger brushes, but they do leave a finish that is as good as it gets.
With any natural brush you’ll want to remove any dust or loose filaments before you first use the brush. Shake it out vigorously, then dip it about 1/2 of its length into the appropriate solvent for the finish you’ll be using, and then gently tap it against the side of the container.
For water-based finishes use synthetic brushes, because the water in the finish will cause natural filaments to swell and lose their stiffness. Most synthetic brushes have polyester or nylon filaments, or some combination of the two. Neither are as absorbent as natural filaments, which means you have to load up the brush more frequently. Most manufacturers whip the filaments to split the ends into flagged ends to give a smoother finish.
For large surfaces use a 2″ to 4″ wide brush, while for smaller panels, frames, edge work, and legs, choose a narrower 1″ to 1-1/2″ brush. It’s true that an angled (or ‘sash’) brush allows finer control in corners and tight spaces, but rather than adding yet another brush to my kit I simply switch to a narrower brush, which I find works just as well.
If you typically work with small items, then pick up a couple of small artist brushes (available with both natural and synthetic filaments). They excel at working in tight spaces, and the super fine filaments allow the finish to flow onto the work easily with virtually no visible marks.
When applying a finish think about scale. A large surface has the capacity to absorb finish at a faster rate than a smaller surface or narrow trim work. Using a heavier load on the larger surface makes it easier to maintain a wet edge. Conversely, applying too much finish to a carved or contoured piece will result in runs and sags that can be difficult to correct. With practice, and paying attention to the feel of the brush as you apply the finish, you’ll learn to identify the correct load for each situation.
When loading the brush you only need to dip the bottom third or half of the brush into the finish, and then wait for the finish to wick into the brush. Before moving the brush to the project, adjust the amount of the load by lightly pressing the brush against the side of the container.
Rather than brushing from one end of a panel to the other end, begin by placing the brush a couple of inches from the end of the panel and move the brush to one end. After completing that stroke, return to the starting point and brush back to the opposite end. As you get to either end of the panel the brush should just glide off the top without moving down the edge of the panel. After completing the first pass, go back and use the tip of the brush to gently work the finish across the edge.
Brush cleaning doesn’t have to be arduous or time consuming. If you’re applying a finish over a day or two, then don’t bother cleaning the brush. Instead, suspend it in a container of the solvent for the finish – just make sure the tip doesn’t stand on the base of the container or it will curl up. Before using again, lightly press the excess solvent out of the brush on the side of the container.
To clean a brush used for varnish or water-based, you want to rinse the brush several times in the solvent for the finish you’re using (mineral spirits for varnish, water for water-based). I do this three or four times, and then wash the brush several times with warm water and dish soap. For a varnish brush, rinse the brush first with a citrus-based cleaner and then again with water to remove the final traces of solvent from the brush.
Shake out any excess moisture by swinging it up and down several times, and then wrap the filaments with a piece of paper – I use strips from paper grocery bags. This allows the bristles to dry, and keeps dust from getting into the filaments.
My particular brush arsenal consists of two brushes for each type of finish. For shellac I use a 2″ wide ox-hair and a 3/4″ synthetic; for varnish, a 2″ and a 1″ bristle brush; and, for water-based finishes a 2″ synthetic and a 3/4″ synthetic. The type of woodworking you do will obviously affect your choice of brush.
Buy good brushes, practice applying the finishes you intend to use, take the time to clean the brushes after use, and you’re three quarters of the way to a perfect finish. The last quarter comes from experience.
The easiest way to stain lighter-colored sapwood so it blends with the heartwood is to stain all the wood with a dye stain, as is shown on the right side of the accompanying picture of walnut. Dye is much more effective than pigment, or any commercial stain that contains a binder.
You can apply the dye several times after each application has dried to get a darker color. Or, with water-soluble powder dyes, such as those from W.D. Lockwood, you can wipe over the stain with a water-damp cloth to remove some of the dye and lighten the color.
You can also apply more of the dye just to the sapwood, after you have stained all the wood, to selectively darken it and achieve a closer blend. But applying dye just to sapwood, and not to all the wood, seldom works well because it’s so hard to get a match – though you could always try it. The worst that would happen is that you would then apply the dye to the entire surface.
Many different lubricants are recommended for rubbing out finishes with an abrasive. Here’s how they differ.
The more waxy or oily the lubricant the better it reduces scratching and sandpaper clogging but the slower it cuts. The more watery the lubricant the more aggressive the cutting but the more pronounced the scratches.
So wax is the most lubricating of the common lubricants suggested. Oil would be next, followed by a mixture of oil and mineral spirits.
On the more aggressive side, straight mineral spirits (paint thinner) still provides some lubrication while allowing the abrasive to cut effectively. Soapy water provides slightly more lubrication than straight water, which still provides enough to somewhat reduce sandpaper clogging.
Oil-based polyurethane is a very durable and hard-curing finish. It bonds well to itself, especially if each coat is sanded a little after it has dried well enough so it powders. This creates fine scratches, which improve the bonding of the next coat.
It’s a good idea to do this fine sanding between coats anyway to remove dust nibs.
But polyurethane doesn’t bond so well over finishes marketed as sealers, especially over sanding sealer. This sealer is good for use under non-polyurethane varnishes because regular alkyd varnishes gum up sandpaper. So to speed production, a sanding sealer can be used for the first coat. Sanding the first coat not only removes dust nibs. It also removes the roughness caused by the swelling of the wood fibers.
Shellac can also be used to seal wood under polyurethane. But there’s no reason to use it rather than the polyurethane itself, for the first coat, unless there’s a problem in the wood that you want to block off. Problems include pine knots, silicone from furniture polishes (which causes “fish eye” or “cratering,” especially on old wood that is being refinished), and odors from smoke damage or animal urine. For these cases, applying a first coat of shellac usually blocks off the problem.
If you do use shellac, you should use the dewaxed variety. The commercial product, available in home centers and paint stores, is SealCoat. Or you can buy dewaxed shellac flakes and dissolve your own in denatured alcohol.
The resin in pine knots contains solvents that will bleed into and through most paints and finishes. This can cause the paint or finish to remain sticky, and it can cause the orange color to bleed through as shown in the accompanying picture of white latex paint applied over pine.
There are two types of products on the market that will block this resin: white pigmented primers and clear shellac. The most well known white primers are Kilz and BIN. The best clear shellac to use is Zinsser SealCoat because it has very little color and a longer shelf life than other shellacs.
Kilz and other brands are available as oil-based and water-based. In comparative tests I’ve found that oil-based works better at blocking the resin than water-based. But the most effective blocker is shellac, both clear (SealCoat) and white-pigmented BIN.
Once you’ve applied the SealCoat or BIN to the wood, you can apply any paint or finish over it. As long as you haven’t sanded through, this first coat should block the resin.
Finishes differ in the amount of color they add to wood. Though you may not notice much of a difference if you are applying the finish over a stain, there is a significant difference when no stain or other coloring steps are used.
In the accompanying picture, you can see the differences clearly.
On the far left is paste wax. It adds almost no coloring to the walnut. Next is water-based finish, which also doesn’t add color, but it does darken the wood a little because of the penetration.
In the middle is nitrocellulose lacquer, which adds a slight yellowing to the wood. Clear (bleached) shellac is very similar. Next is polyurethane varnish. Varnishes can differ quite significantly in the amount of yellow/orange color they add to the wood. But most polyurethane varnishes are very close to this.
Finally, on the far right is orange (amber) shellac, which adds more orange coloring than any other finish.
So a big consideration when choosing a finish for unstained wood is the color you want to add. One of the main reasons, in fact, for choosing a water-based finish is to keep the color of the wood the same while still achieving a protective coat (which wax doesn’t provide).
The usual finishes that are sprayed are lacquer, shellac and water-based finish. These finishes dry fast, sometimes too fast in warm temperatures to successfully brush onto large surfaces. Spraying overcomes this problem.
Oil-based varnish, including polyurethane varnish and oil paint, can also be sprayed, of course, because any thin liquid can be sprayed. But you need to be aware of a significant difference. Varnish dries much slower than the other finishes, and unlike lacquer, shellac and water-based finish, each coat should be allowed to fully dry before the next coat is sprayed.
You may typically spray lacquer, for example, spray several coats at a time without allowing drying in between. The drying will be a little slower because there is more solvent in the thicker application that has to evaporate for the finish to harden. But the time difference won’t be great, and there won’t be any problems unless you build the finish so rapidly that it sags or puddles.
Varnish and polyurethane varnish (and oil paint) are different. For varnish to cure, oxygen has to work its way into the finish to cause it to crosslink. If you spray several coats of varnish one after another, the top surface will dry well before the varnish at the bottom, and this will significantly slow the penetration of the oxygen. The result will be a finish that feels dry at the surface but is still so soft that you can indent it with your fingernail, and it will remain like this for many days or weeks.
You can always allow way more time for the finish to cure all the way through. You can also speed up the curing by raising the heat in the room or applying heat with a heat lamp.
But this could cause the finish at the surface to wrinkle as the finish at the bottom dries and shrinks.
So it’s best to allow each sprayed coat of varnish or oil paint to fully dry (enough so sanding produces dust) before applying the next coat.
To achieve an even coloring with darker colored woods, it’s always best to use only heartwood to begin with. But this isn’t always possible. So you may want to “equalize” the coloring of the sapwood and heartwood.
One method is to bleach the wood using two-part bleach (sodium hydroxide and hydrogen peroxide). This will remove the coloring from the heartwood, so you can then stain the wood back to the color you want.
But it’s usually better to equalize the sapwood to the color of the heartwood.
The easier way to do this, if you intend to stain the wood dark, is to use a dark dye stain as shownin theaccompanying picture. Light colored dye stains don’t work as well,manned stains that contain binders, such as oil, water-based and lacquer stains, work even less well.
Though more difficult, the best way to equalize the coloring is to spray a dye stain just on the sapwood, as shown on the middle stripe in the second accompanying picture. You can then follow with a binder stain if you want to further equalize the coloring, as shown on the stripe second from the right. Finally, apply the finish, which will produce the true coloring.
Whenever water or any stain or finish that contains water comes in contact with wood, it causes the wood fibers to swell, which is called “grain raising” or “raised grain.” After the water has dried the wood feels rough to the touch, and thinly applied finishes also feel rough.
Raised grain occurs no matter how fine you sand the wood before wetting it. Because you can’t prevent raised grain if you use a water-based product, you need to deal with it so the final finish comes out smooth. There are two methods:
The first is to raise the grain and sand it smooth before applying the water-based product.
This is called raising the grain, sponging, whiskering or dewhiskering. Once sanded smooth, the grain won’t raise again nearly as much as it did with the first wetting.
After sanding the wood to about 150- or 180-grit, wet it with a sponge or cloth just short of puddling. Let the wood dry. Overnight is best, but three or four hours is usually sufficient if the air is warm and dry. Then sand the raised grain smooth with the same grit sandpaper you used last or one-numbered grit finer.
The goal is to smooth the raised grain without sanding deeper than necessary, in which case the newly exposed grain may raise again when wetted. Dull sandpaper works best because it doesn’t cut deeply so easily.
Raised grain is difficult to show in a picture, but it generally appears duller, as on the right side of the accompanying photo, which was wetted, dried overnight and not sanded smooth.
The second method is to “bury” the raised grain. If you’re applying a water-based finish, simply sand the first coat smooth after it dries, just as you would do with a solvent-based finish, except with a coarser sandpaper grit—for example, 220 grit. If you’re applying a water-based stain under a water-based finish, wait until after the first coat of finish has been applied and has dried to sand smooth. Sand lightly so you don’t sand through, which might remove some of the color.