The Basics of Wood Finishing
The Basics of Wood Finishing
Wood finishes can be intimidating and daunting, but they don’t have to be. It’s really easy to put down a good finish, if you know what you’re working with and how to apply it.
Ready to learn how to make your project look great? Read on, we’ve got some great info for you.
Why Apply a Finish
There’s really only two reasons to apply a wood finish to your woodworking project, protection and appearance.
You want your woodworking project to look nice for years, right? A good wood finish will liven up the wood grain and protect the wood for years.
Wood is a porous material, capable of soaking in anything that gets on it, such as oils, dirt, and chemicals. A wood finish will seal the wood and keep “gunk” out of the wood grain. You’ve put a lot of time into your projects, so you’ll want to keep them looking good for years.
Some woodworking materials are not that great looking, such as Medium Density Fiber board (MDF), so painting it will not only protect it, but will also change it from dull tan to bright and flashy.
Many woods have muted wood grains, others have vibrant grains, either way, staining them will make that grain pop and really emphasize the beauty of the wood. Stain and clear coating real wood makes it the much more beautiful.
So, now that you know why finishes are uses, let’s look at some that are available.
Types of Finishes
There’s numerous types of finishes out there. Some are used alone and some in conjunction with others. You don’t have to use all of them, just the ones that fit your needs. The information below will get you started in finishing your projects like the Wood Work Boss you are.
Paint is a basic finish that covers and protects the material that it’s applied to. Paint isn’t usually used over natural wood, but it can be. If the paint coverage is thin, or semi-transparent, then the wood grain can show through, with dramatic effect.
Paint is commonly used on woodworking projects made of MDF or plywood, as well as woodworking projects that require color.
Stain is usually used over natural woods, or plywood, so that the grain is visible and accentuated. It can really make wood pop and add warmth to not so fancy woods.
The purpose of clear coats is to seal and protect the wood, while allowing the grain to be seen. No need to hide beautiful wood, right?
There’s quite a few options to choose from, so let’s take a look.
Wax is a simple finish to apply, as it’s simply rubbed on a buffed to a sheen. It works best on fine-grained woods that have been sanded to a smooth surface. It’s not best on rough-grained woods, such as Oak or Ash.
Wax is not only applied to bare woods, but also on top of over finishes, such as Shellac, to protect them from moisture.
Oils are an easy way to finish woodworking projects as they are simply applied heavily then wiped down to a dull sheen. They are quick to apply and can be re-coated over the years. Oils do not provide a shiny surface, though and may feel sticky for some time.
Here’s a few options if you want to wood finish your projects in oil.
Linseed oil is made from flax seeds. It’s applied by brushing or wiping it on in coats and wiping it down with dry rags until the desired protection/finish is achieved.
Tung oil is similar to Linseed oil. It’s made from the kernels of Tung tree seeds. Like Linseed oil, you you brush or wipe it on, then wipe off the excess. It protects the wood without providing much shine.
Mineral oil is applied like Linseed Oil and Tung Oil. So, why is it mentioned? Well, when purchased in food safe grades it can be used on childrens’ toys and cutting boards.
Shellac is an age old finish that’s not used much these days. Shellac is a resin that is dissolved in alcohol and then brushed on to projects. It’s not known for it’s moisture protection, so it’s fallen out of favor over the years. Warm coffee cups, or plates, will leave a ring in a shellac finish, as will sweaty cups. It’s not the best choice for table tops.
Varnish is also a resin and solvent based finish, similar to shellac and lacquer. Varnish is usually wiped or sprayed on. More durable than shellac, varnish will stand up to moister. Spar varnish is used in wooden boat applications.
Unlike oils, lacquer dries by solvent evaporation to a hard and durable finish that does not need re-coating. Lacquer can also be polished, but is available in matt and satin finishes. Lacquer can be applied by brush or by spraying. A solvent is necessary to clean the brush or spray gun.
Lacquers dry much quicker than oils, so finishing can be done more rapidly. Since lacquers dry hard, they are prone to cracking and chipping with age.
Polyurethane is basically a liquid plastic that provides a durable finish when it cures. It’s available in gloss to matt finishes and is applied by wiping, brushing, or spraying. A solvent is necessary to clean the brush or spray gun. Polyurethane does not dry quickly, so it will take a bit of time to finish your project.
Due to it’s slow drying time, polyurethane is prone to collecting dust as it sets up. Keep this in mind when you choose where to finish your projects.
Polyacrylic is a water based polyurethane which dries quickly to a tough durable finish. It cleans up with soap and water and is usually applied by brushing or spraying. Polyacrylic is a very easy to use and clean up, so it’s gaining great favor with woodworkers.
Ways to Apply Finishes
There are several ways to apply finishes. Some are simple and others a bit more involved.
Many finishes can be wiped on with a rag, such as oils, varnish, and shellac. Excess is wiped off with a dry rag. This is a quick way to finish projects. When done, toss the rags away. Easy clean up, huh?
Brushing a finish is a bit more complex than wiping on a finish, as it requires a brush which requires cleaning. Brushing may also leave brush marks in the finish, so it’s important to purchase quality brushes. They are less prone to leaving brush strokes in the finish.
Spray on finishes are more complicated as they require a spray gun to apply. Spray guns can be costly or inexpensive, so one doesn’t have to spend a bunch to lay down a nice finish. Of course spray guns do require clean up when the task is complete.
Actually, a spray gun is not always needed to spray a finish. Paints and clear coats are available in spray cans, which make it easy to lay down a nice finish without much fuss and cost. Clean up is quick and easy. Simply turning the spray can upside down and spraying for about 20 seconds will clean out the spray nozzle.
So, now you have enough info to choose the appropriate finish for you woodworking treasures. Stain and clear coat will provide a warm finish to natural wood. Paint will do wonders for MDF and plywood. Any way about it, your project won’t be finished without a finish.
In closing, here’s a key point to remember. Finishes put off fumes and spray dust, so protect your lungs when you use them. A respirator will keep your lungs clear for years to come.