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Outdoor Finishes

Outdoor Finishes

Simple to Super Durable

by Brad Holden

Outdoor finishes have one thing in common; they all require maintenance. Of course, paint is unequaled at protecting the wood from its two biggest enemies: moisture and ultraviolet (UV) light. Moisture causes the wood to rot, and sunlight bleaches out its natural color. Still, who wants to cover-up beautiful wood with paint? If you want the wood to show through on your outdoor projects, you need a clear finish.

There are three basic clear finishes for outdoor furniture: exterior oil, exterior varnish, and an epoxy sealer with an exterior varnish topcoat. Application ease and service life are the two major differences between these finishes.

Of the three clear exterior finishes, exterior oil is by far the simplest finish to apply. Just flow it on, let it soak in and wipe off the excess. Unfortunately, oil offers the least amount of protection and it must be reapplied every season. Exterior varnish, on the other hand, is more difficult to apply: up to 8 coats have to be carefully brushed on. While exterior varnish offers excellent protection from moisture and UV light, it has to be recoated every few years to maintain that protection. An epoxy sealer with an exterior varnish topcoat is the most durable outdoor finish and can last for many, many years. However, the initial application does take longer then exterior varnish. 

 

Exterior Oil

An exterior oil finish is definitely the simplest, quickest way to treat an outdoor project. On the downside, it will only give you about a year of protection from the ravages of outdoor life. Oil finishes don’t provide a protective film  that sits on top of the wood like varnish does. Instead oil soaks into the wood fibers and dries. Exterior oils have added trans-oxide pigments for UV protection and mildewcides to protect against mold and mildew. You’ll find colors ranging from dark brown to light amber.

Application is simple: a garden sprayer and a rag are all you need. First, flood the surface of your project with oil. I use an inexpensive hand pump garden sprayer. Its fast, easy and only costs about $8.00.  Let the oil soak in according to the manufacturer’s directions, then wipe it off. That’s it. Done! Depending on local conditions, you’ll have to reapply about once per year. The built-in UV protection should keep your wood looking natural for many years (as long as you keep up with the applications).

Click on any image to see a larger version.




 

Exterior Varnish or Urethane

Exterior varnish or urethane (both finishes are technically “varnishes”) builds a protective layer over the wood. It offers superior protection and durability over an oil finish. Often, the term “Spar” is found in the name, but this does not indicate any additional or special ingredient. The term “Spar” originates with its use as a coating for the spars on sailing ships. All exterior varnishes are formulated to protect against moisture and UV radiation.

Exterior varnish is applied with a natural bristle brush in multiple coats. Manufacturers recommend eight thin coats for maximum protection and a deep lustrous finish. Sand the hardened varnish lightly between each coat.

Exterior varnishes cure to a more flexible film than ordinary varnish. The flexible coat is not as likely to crack from seasonal wood movement caused by humidity extremes in an outdoor environment.

Exterior varnish will usually last  2-3 years before it starts to look chalky. As soon as you see a chalky film start to develop, it’s time to freshen the finish. Simply sand the topcoat smooth, and apply a new coat of varnish. Don’t put this important maintenance step off too long or cracks will develop in the finish allowing moisture to penetrate and degrade the wood. That will necessitate a complete strip and refinish to restore the furniture. You don’t want to go there.




 

 

Epoxy with Exterior Varnish

An epoxy sealer with exterior varnish topcoats is the most durable, but also the most labor-intensive finish you can apply to outdoor furniture. This is the finish favored by boat builders so you know it's going to last a long time. Epoxy and exterior varnish enjoy a symbiotic relationship: The epoxy forms an impenetrable moisture barrier that prevents seasonal swelling and shrinking of the wood. This dimensional stability in turn gives longer life to the exterior varnish because it no longer has to stretch and shrink with the wood The exterior varnish returns the favor by providing UV protection, without which the epoxy would rapidly deteriorate.

Apply three thin coats of epoxy. The best way to get thin, even coats is to use a foam roller cut in half. It works kind of like a squeegee. Epoxy cure times vary depending on their formulation and the ambient temperature. Be sure to use an epoxy with a long enough open time (approximately 30 minutes), so it doesn’t set up before you’re done putting it on. For large projects, mix the epoxy in small batches so you can finish an area before the epoxy sets. Also, for optimal flow out and penetration into the wood fibers, make sure the epoxy you use doesn’t contain any thickeners. Always read and follow the instructions that come with your epoxy. If possible, apply the epoxy undercoat prior to assembling the parts. You can recoat without sanding while the previous coat is still soft but not sticky. If the epoxy seems uneven or bumpy, allow it to harden. Then, sand it smooth and apply the next coat.

Before applying the varnish topcoats, I use a card scraper or sanding block with100 - 120 grit sandpaper to level the cured epoxy (see photo below left). The sanded surface also provides some tooth for the spar varnish to adhere to.

Rinse the sanded epoxy with clean water and dry with paper towels. The rinse water should not bead on the surface. Beading indicates that contaminants from the epoxy curing process are still on the surface and could interfere with the varnish bond. To remove the contaminants, wipe down with mineral spirits and dry with paper towels or a rag. Follow this with eight coats of exterior varnish, sanding lightly between coats.

 

Sources

Source information may have changed since the original publication date.

Epoxyheads, epoxyheads.com, 866-376-9948, epoxy resin #7710 $33.00/qt; epoxy hardener #7720 $17/ 1/2 pt.; metered pump set #7801 $11.

Penofin, penofin.com, 800-penofin, Original Blue Label Oil Wood Finish, $15/qt.

Home Depot, homedepot.com, 48 oz. Chapin multi-purpose hand sprayer model 1002 $8.

Home center/hardware stores, exterior oil varnish or urethane.

 

This story originally appeared in American Woodworker April/May 2007, issue #128.

 

April/May 2007, issue #128

Purchase this back issue.




1. Sand out any unevenness and defects in the cured epoxy before applying the exterior varnish topcoats.




 

Make Poplar Look Pretty

Make Poplar Look Pretty

Give this useful but unattractive wood a makeover.

By Kevin Southwick


The wood we know as poplar has many common names, such as tulip poplar, yellow poplar, tulipwood, yellow tulipwood, tulip tree, whitewood and canoewood. The “tulip” part of these names comes from the tulip-like flower the tree produces in the spring. Where the “poplar” part of these names comes from is a mystery, because the tree is not even a true poplar—it’s a member of the magnolia family. In fact, poplar is known as the “king of the Magnolias.” It’s also the tallest hardwood tree in North America.

Regardless of what it’s called, Liriodendron tulipifera Magnoliaceae produces very useful and versatile lumber. The tree grows fast, with a straight trunk and no branches near the ground. That translates to knot-free boards that are available in expansive widths and thicknesses. Poplar is economical, costing considerably less than other hardwoods such as maple and oak, and its finely textured lumber works well with both hand and power tools. These qualities make poplar suitable for many furniture and construction applications.


An ugly duckling

So why isn’t poplar popular with furniture makers? The answer is simple: The wood is just plain homely. Its color ranges from pale yellowish white to an odd shade of green, and boards are often discolored by dark gray or purplish streaks. To top it off, poplar doesn’t stain well with traditional wood stains. In fact, it can get ugly really fast because it blotches so easily. About the only time furniture makers use poplar as a primary wood is when the piece is going to be painted.

 

Transformed

Poplar has too many desirable furniture-making qualities to be limited to “paint-grade” service. Fortunately, by using a special approach, it’s possible to make this ugly duckling glow beautifully. This process will transform poplar’s odd green color to any brown wood tone you like. However, dark streaks will still show—they’ll need to be avoided or placed strategically in the design and called “character.”

The key to giving poplar a rich, even stain color is to control its horrible blotching tendencies. This requires starting with a very effective stain controller (also called wood conditioner or pre-stain sealer). The commercial stain controllers I tested didn’t provide enough blotch resistance, so I developed a simple recipe to make a controller with the necessary strength. This recipe and the finishing steps that follow work well on any wood that’s prone to blotching.

After applying the stain controller, use a two-step coloring process for better control and color intensity. This coloring method combines the benefits of both dye and pigment stain. The dye provides a ground color as strong and rich as needed, and the pigment ensures that the color doesn’t fade and become dull over time. The dye and pigment colors shown here are both a medium-dark “warm” brown. They combine to create a rich chocolaty tone on both the green heartwood and pale sapwood. Your color choices may be different.

 

How-to

1. Prepare the surfaces by sanding to 180 grit. Be sure to sand by hand after you power sand, to eliminate swirl marks. Pay extra attention to the end grain.

2. To make the stain controller, mix one part General Finishes Clear Gel Varnish with three parts paint thinner. Apply the stain controller with a rag and allow it to soak in (Photo 1). Be sure to saturate the wood, especially the end grain. After a couple of minutes, but before the stain controller starts to set up (5-10 minutes), use clean, dry rags to remove any that has not soaked in. Be sure not to leave any wet spots or streaks—they’ll show up when you apply the stain. Let the wood dry overnight. This step is intended to seal the wood approximately 60%-75%, which is usually enough to control blotching and still allow the stain to penetrate.

3. Wash the partially sealed surface with a mixture of dish soap and water to “open” the top layer of wood cells so they’ll absorb the dye easily (Photo 2). This step won’t cause any significant grain-raising because the surface has been treated with the stain controller.

4. Hidden blotches will reveal themselves as the water dries (Photo 3). Areas that are extra-porous soak up more water. This means they’ll stay wet longer, so they’re easy to identify. The longer they stay wet, the worse the blotch will be. Fortunately, even super-absorbent areas can be tamed if they’re found and treated with extra stain controller before color is applied.

5. Mix TransFast Medium Brown Water Based Dye following the label instructions and apply it generously, using a rag (Photo 4). Allow the dye to saturate the wood, then remove the excess with clean rags. Allow the wood to dry until the water has completely evaporated (2 hours).

6. Check the workpiece and selectively apply clear gel to any blotches or end grain that are already dark enough from the dye step (Photo 5). This is your last chance for blotch reducing.

7. Apply a coat of General Finishes Medium Brown Gel Stain (Photo 6). Then let the piece dry overnight.

8. Apply two coats of 2 lb. cut amber shellac (Photo 7). Although shellac is a durable finish, I know that this table will often be used as a place to rest a coffee cup, so I’ll add a coat of oil-based satin polyurethane to prevent water rings.


This story originally appeared in American Woodworker October/November 2010, issue #150.

October/November 2010, issue #150

Purchase this back issue.

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1. Start by wiping on a strong stain controller to keep the poplar from blotching when you apply the dye and stain. Make a strong stain controller by thinning gel varnish with mineral spirits.


2. Wash the sealed surface with soap and water so the dye will soak in, rather than bead up on the surface.


3. Blotch-prone areas will stand out as the water dries, because they’re super-absorbent. After the wood has thoroughly dried, apply an additional coat of stain controller to these areas.


4. Apply a coat of medium-brown dye to create a uniform ground color.


5. Look again for blotching or dark end grain. Seal any areas that have gone extra-dark with a coat of gel varnish just before you apply the gel stain in the next step.


6. Apply a coat of medium-brown gel stain. Gel stain adds richness to the overall color and helps to keep the dye from fading.


7. Apply two coats of amber shellac to add depth and tone, followed by a more protective topcoat, if necessary.


Turn green to gold

Oxalic acid works miracles on poplar’s green heartwood. Simply mix a saturated solution of oxalic crystals in hot water and brush the solution on the wood. As the solution dries, the green heartwood will turn to a golden brown and the white sapwood will take on a warmer shade of pale. A second application of the solution after the first has thoroughly dried usually helps the results—and it can’t hurt. Oxalic acid is poisonous, so let the surface dry completely and then rinse it thoroughly with water to remove any acid that remains. Note that this treatment does nothing to reduce poplar’s tendency to blotch, so you’ll still need to follow the recipe to end up with a great-looking finish.

Oxalic acid is primarily used to restore the natural color of grayed, weathered, exterior wood—it’s the active ingredient in deck-renewing products. Restorers and woodworkers use oxalic acid to remove black water stains from wood. It’s available at most hardware stores.

 

Turning Wood: Socket Chisel Handles

Turning Wood: Socket Chisel Handles

Here’s a 1-2-3 system for getting a perfect fit.

By Tim Heil


High-quality socket chisels— such as the Stanley Sweathearts and Lie- Nielsens—are making a big comeback. Why would these companies choose the socket style? Well, it’s all about you, the user. If you’re not satisfi ed with a handle’s shape, you can change it. If you want a diff erent wood—no problem. Th e handle of a socket chisel isn’t glued or fastened to the tool, so you just remove it and make your own.

Truth is, woodworkers have been doing this for years. In the age before plastics, when a wood handle on a socket chisel split or mushroomed, replacing it was easy. But not all were fixed. Today, there are loads of wonderful old socket chisels going for a song, merely because they have busted or missing handles.

I’m a turner with a thing about handles— I just love making them. Screwdrivers, awls, ice cream scoops: If it’s got a handle, I’ve got to make my own.

When I first turned handles for socket chisels, I would make a few crude measurements of the socket and just go at it. If the taper on the handle’s shank wasn’t quite right, I guessed where it was off and tried again. While this method works OK, I’ve since found a measuring system that’s much more reliable. Following these steps, your shank should fit tight right away.

First, turn a cylinder that’s an inch or two longer than the length of the handle you’re going to make (of course, the full length includes the shank). Th e narrow end of the shank will most likely be a small diameter (anywhere from 1/4" to 3/8"), so I prefer using a cone-shaped revolving center in the lathe’s tailstock. Th is gives me more room to maneuver the parting tool when cutting the shank’s taper.

 

Measure the socket

Start by wrapping a small piece of notebook paper around a pencil, forming a cylinder (Photo 1). Push the cylinder all the way down into the chisel’s socket (Photo 2) and let the paper unroll into a cone. (You may have to help it a little bit.) Once the paper has fully conformed to the socket’s taper, put a couple of pieces of tape on the paper, to hold its shape. Th en draw a line on the cone, following the top of the chisel’s socket (Photo 3). Remove the cone—you’re all set to take three measurements.

First, set a divider to the distance between the pencil mark you made and the end of the cone (Photo 4). Transfer that distance to the handle blank (Photo 5). Second, set a caliper to the diameter of the cone at the pencil mark (Photo 6). Turn the blank to this diameter, immediately to the right of the mark indicating the shank’s length (Photo 7). (I fi nd it easier to do this if I start roughing out the shank at the same time.) Th ird, reset the caliper to the diameter of the cone’s end (Photo 8). Turn the end of the shank to this diameter (Photo 9), then form a straight taper up to the end of the shank.

 

Test the fit

If all has gone well, the shank should perfectly fi t the socket. Just to be sure, perform a simple test. Rub a piece of chalk on the inside of the socket (Photo 10). Turn off the lathe, pull away the headstock and push the socket onto the shank. Twist the chisel a few times and remove it (Photo 11). If the fi t is correct, most of the shank will be coated with chalk; if it’s not, the chalk will show you the high spots that need to be removed. If the fi t is too loose, your best bet is to cut off part of the shank and start over from the beginning. Don’t worry—the turning goes pretty quick.

Once the fi t is OK, lengthen the shank by about 1/8" (Photo 12). (Notice the small gap between the end of the socket and the end of the shank on the handles shown on page 30.) Th is gap allows you to drive the shank tight into the socket. Th e end of the handle shouldn’t butt up against the top of the socket. If it does, the handle could split when you strike the chisel.

Turn the handle to any shape you wish (Photo 13). Th ere’s really no right or wrong here; traditionally, chisel handles came in many diff erent shapes and sizes. If your work requires you to strike the chisel hard, you may want to put a ferrule on one or both ends of the handle to prevent it from splitting. Turn off the lathe from time to time and test how the handle feels. When you’re done, part off (Photo 14). To install your handle, just drive it into the socket with a mallet. With a tight fi t, there’s no need for glue. When you apply fi nish to the handle, don’t put any on the shank. If the shank is too slippery, it won’t stay seated in the socket.


This story originally appeared in American Woodworker February/March 2012, issue #158.

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1. Chisel sockets come in many different sizes, so you’ll need to take some measurements before turning the handle. Start by cutting a piece of notebook paper about 4” square. Roll it up around a pencil.


2. Push the paper cylinder all the way into the chisel’s socket. Let go of the paper—it will unroll to form a cone. The cone will be exactly the same shape as the socket.


3. Stick one or two pieces of tape on the cone to hold its shape. Mark the cone at the end of the socket. Remove the cone from the chisel.


4. Set a divider to the distance between the pencil mark and the end of the cone.


5. Mark this distance from the tailstock end of a blank you’ve roughed out.


6. Set a caliper to fit the cone at the mark you drew at the end of the chisel’s socket. This will be the major diameter of the handle’s shank (the part that fits into the socket).


7. Turn the blank to the major diameter, just to the right of the pencil line. Rough out the rest of the shank’s taper.


8. Reset the caliper to fit the end of the cone. This will be the shank’s minor diameter.


9. Turn the end of the shank to the minor diameter, leaning the parting tool at about the same angle as the rough taper. Cut a straight taper between the major and minor diameters.


10. Check the fit of the shank in the chisel’s socket. First, coat the inside of the socket with chalk dust. Then turn off the lathe and pull away the tailstock.


11. Push the socket onto the shank and twist it a few times. If its taper is correct, the full length of the shank will be coated with chalk. If it’s not correct, only the high spots will be coated.


12. Once the taper is correct, lengthen the shank about 1/8" to the left.


13. Shape the rest of the handle as you wish. Stop the lathe and remove the handle from time to time to test how it feels.


14. Part the handle from the blank using a spindle gouge. (My gouge is very short, from turning so many handles!)