EXTERIOR POLYMERIZED TUNG OIL

There are probably no greater challenges in formulating a wood finish than those posed by an exterior application. Many variables work in concert to destroy an exterior finish; heat, water and especially light.

The degree of protection for an exterior wood surface is a function of the type and amount of coating applied to the surface initially, a regular maintenance schedule, as well as the wood species itself. Some wood species weather better than others, but in time all wood suffers degradation due to outdoor weathering as do the coatings applied to protect them.

Ultraviolet radiation sets into motion a process known as photo degradation. Photo degradation begins when ultraviolet (UV) light causes damage to the polymers in either the coating or the wood fibers. The initial insult is fairly minimal, but with continued UV exposure and compounded by the second contributor to coating failure, moisture, the process soon escalates with rapid and extensive damage occurring to the coating and then to the wood substrate itself.

Formulating the best exterior wood finish begins with the essence of the coating. Sutherland Welles Ltd. ® Pure Polymerized Tung Oil is the perfect wood preservative. It has been used for centuries to waterproof all types of exterior woods. The ancient Chinese recognized the amazing qualities of Tung Oil. Throughout history, the Chinese have used Tung Oil to waterproof the masts and sails of junks and according to legend, to seal the Great Wall! During World War II, Tung Oil was used by the military in the Pacific to coat engine parts to prevent rusting. Tung Oil is resistant to many alkalis and acids as well. After its resistance to water, Tung Oil’s ability to remain flexible yet durable makes it perfect for exterior applications where the continual expansion and contraction of wood surfaces as they are exposed to moisture and drying heat stress the integrity of the coating. Moreover, unlike linseed oil, which darkens with age and exposure to UV light, Tung Oil’s light amber color is consistent throughout the life of the coating

POLYMERIZATION AND FORMULATION

As Tung Oil dries and cures, the molecules join together in a tight complex formation. This process is the secret to Tung Oil’s effectiveness as a finish. The cross linking of the oil’s molecules makes the surface waterproof and impervious to many chemicals. The bonding also gives flexibility to the surface, making it capable of withstanding wear and tear.

Sutherland Welles Ltd. ® uses a process called polymerization to intensify Tung Oil’s natural cross-bonding tendency. Polymerization is a cooking process that changes the molecular structure of the oil and further improves the natural cross-bonding reaction of raw Tung Oil.

Many other manufacturers of Polymerized Tung Oil will claim they polymerize their oil, but their "cook" is not as extensive as ours and requires formulation which includes additives such as varnishes and urethanes to improve the hardness, durability, and lustre of the finish. This adds to the toxicity of the finish and inhibits the penetration of the oil into the wood fibers.

The polymerization process used by Sutherland Welles Ltd. ® is very sophisticated and "cooks" the pure, raw Tung Oil to its "maximum thermal threshold". Controlling the "cooking" and the "cooling" is an expensive process that at its perfect point produces an oil that has maximum durability and a gorgeous sheen. If the process isn’t well controlled the oil solidifies to the consistency of an eraser and the entire batch is lost.
The intricacy and therefore expense of the process is what leads most companies to formulate with modifiers. They believe they can achieve the same results with a cheaper process and formulation. In time, the varnishes and urethanes discolor and deteriorate and with it the wood.

Sutherland Welles Ltd. ® has researched and implemented driers with the lowest toxicity available. We are now using solvents that are "cleaner" reducing the environmental impact and minimizing a finisher’s exposure to toxic chemicals.

FORMULATING FOR THE EXTERIOR APPLICATION

The next step in producing a superior exterior finish is adding the best UV guards and mildewcides available that help preserve the finish. Sutherland Welles works closely with our chemical supplier to keep abreast of the latest research developments in coating additives to maintain the highest coating performance possible. At this point in time, we combine two UV additives. The first absorbs UV radiation converting the absorbed UV radiation into harmless heat energy that is then released across the coating. The second is a light stabilizer, which neutralizes the effects of the by products of photo degradation known as "free radicals" from continuing the chemical process of coating breakdown. The third additive, a mildewcide or algaecide, prevents the colonization of fungal growth on and into the coating surface. Fungal growth produces discoloration, marring and eventually failure of the coating.

FINISHING CONDITIONS

Ideal conditions are a temperature range of 55-75° F with humidity less than 65%. Whenever you finish in conditions out of these recommended ranges you may experience difficulty in applying the finish and you will need to allow for longer curing times. Reapplying finish before the previous coat is adequately cured causes STREAKING and FLASHING of the finish. This is evidenced by dull areas in the finish where moisture is trapped. Avoiding streaking and flashing in the finish is a function of adequate curing time. Curing time is a function of finishing conditions, thickness of coat applied, lustre being used, and number of coats previously applied.

INITIAL FINISHING SCHEDULE

The initial finishing schedule is what optimizes coating performance and longevity. Simply said; the more coats you apply, as deep as possible, to new wood provides the best protection. We recommend multiple, thinly applied coats for best adhesion and maximum performance.

The new wood surfaces should be sanded with no higher than 200 grit sandpaper to allow for maximum penetration of the finish into the wood pores. We recommend two coats of the Exterior Polymerized Tung Oil Sealer be applied according to the directions on the label. The topcoat is formulated in a Medium Lustre consistency for two reasons. First, the higher oil content is needed to protect the surface. Secondly, the sheen produced by the Medium Lustre helps to "bounce" UV light off the wood surface which offers some degree of UV protection. This is how the term "bright work" on sailing vessels came to be – the bright sheen of the wood finish has a function. Our Polymerized Tung Oil offers a lower sheen than our Marine Spar Varnish making it more suitable in applications where a hand-rubbed sheen is desired. We recommend four-six coats of Exterior Medium Lustre Polymerized Tung Oil if the Tung Oil will be applied using a wiping technique, that is applied, allowed to penetrate and then wiped off. This lowers the sheen as well as the amount of oil that resides on the surface; therefore more applications are required to maximize longevity. If the Tung Oil is applied using a surface or film technique; that is applied with a brush in thin coats and allowed to cure between coats without being removed or wiped, then three coats offer adequate protection. Please be sure to verify cure of the previously applied coat prior to re-coat. Surface applied oil can take longer to cure due to the minimal amount of drier we add, number of coats already on the surface and the finishing conditions such as temperature and humidity.

MAINTENANCE

After the initial finishing schedule, the most important component to coating longevity is a regular maintenance schedule. No coating lasts forever. The maintenance schedule will be dictated by the degree of exposure the coating is subjected to. Consistent exposure to bright sunshine, high moisture, or high temperatures will require more frequent (annual maintenance). For other more moderate exposures, the average coating life is about three years. The flexibility of our Polymerized Tung Oil serves to reduce surface failure by allowing the finish to move with the wood. The fractures in the finish tend to be fine, microscopic lines, which minimize moisture invasion and are easily filled when another coat of Exterior Polymerized Tung Oil is applied. Coat after coat can be applied because of our Loc-Lamin® Finishing System that insures adhesion from coat to coat all firmly bonded into the wood pores, regardless of when it has been applied.

MAINTENANCE APPLICATION

Clean the wood surface with 1 cup of ammonia and to a gallon of water. Let the surface dry completely. Lightly sand with 400 grit sandpaper, remove the dust and re-coat the wood with the Exterior Polymerized Tung Oil.
If the surface has developed green mildew, treat with 100% chlorine bleach until all visual mildew is gone. Wash the surface with clean water without adding ammonia. Let dry completely and proceed to re-coat with Exterior Polymerized Tung Oil.

SPECIFICATION FOR EXTERIOR DECKS, PORCHS, AND OUTDOOR FURNITURE USING
EXTERIOR POLYMERIZED TUNG OIL

Please be advised that for finishing exterior decks, porches and outdoor furniture with our Exterior Polymerized Tung Oil the following guidelines are in addition to information provided on the label and are more project specific.

Exterior Decks and Porches
Exterior decks present a different process that departs from what we typically recommend for an exterior finishing schedule per our product label. The concept here is to use a lower solid and fewer coats in an attempt to keep the finish more in the wood than on the wood, which facilitates an easier maintenance program and a better aesthetic.

Decks typically have distinct traffic patterns due to furniture configuration, entrances, etc. that set up specific wear patterns. In an effort to be able to re-oil the entire deck easily, and/or to treat wear areas, a lower solid will be easier to maintain. The other reason to use only the Exterior Sealer is to avoid creating a surface that becomes too slippery and therefore dangerous when wet which occurs with multiple coats of a higher solid.

Outdoor Furniture
The concept of finishing outdoor furniture also departs from what we typically recommend for an exterior finishing schedule per our product label. The concept is similar for furniture as it is for decks but for slightly different reasons. The first reason is the aesthetic. Most people prefer a lower sheen than is achieved with using both Sealer and a Medium Lustre topcoat. Maintenance is again a concern. Typical wear on furniture is extreme on horizontal surfaces and not on vertical and underneath areas therefore you want to use a product that gives protection for a period of time but more importantly gives you a process to refurbish the surface without endless surface preparation. The goal is to keep the maintenance process simple; clean the surface and re-oil. The majority of the time we will recommend using just the Exterior Sealer just as we do on decks. Occasionally, we will use Exterior Medium Lustre if the surface has an open grain such as mahogany. You still get a low sheen, but the protection is improved with a higher solid.

The maximum amount of protection comes from using our Exterior Polymerized Tung Oil as a surface or film finish, which means an application that is brushed on and left to cure on the surface – essentially a Varnish. The key to coating longevity and ease of maintenance lies in the application of thin, multiple coats that are cured properly which gives the film superior flexibility and adhesion. Our formulation includes two ultraviolet guards and a fungicide which work to maintain coating integrity.

All that said; the longevity of a clear, non-pigmented coating is a function of the amount of ultraviolet exposure. In coastal areas, and South/West facing exposures, maintenance coatings can be as frequent as quarterly! In North facing exposures, we’ve seen coatings last 14 years! Timely maintenance minimizes your labor dollar to maintain the surface because the surface prep is minimal- clean the surface and re-oil with one coat to keep the surface looking as good as the original finish.

Environmental Specifications:
Ideal conditions are a temperature range of 55-75° F with humidity less than 65%. Whenever you finish in conditions out of these recommended ranges you may experience difficulty in applying the finish and you will need to allow for longer curing times. When working outside, do not apply the product in direct sunlight. Avoid finishing late in the day when dew may form and the coating cannot properly cure.

Please note: The process described below is intended for working outdoors with air moving across the surface. When you are using the Exterior Polymerized Tung Oil, in an indoor facility where climate control is difficult to maintain, curing times can be longer. Make sure the previously applied coat is properly cured prior to re-application to avoid streaking and flashing of the coating.

Cure Test: To avoid STREAKING AND FLASHING in the finish perform the cure test prior to applying a coat of finish. Streaking and flashing are the appearance of dull spots in the finish. This occurs when moisture is trapped in the layers of finish due to insufficient curing time. Push your finger tips against the grain of the wood over various parts of the surface to be re-coated. If they glide easily over the surface – you are ready to apply your next coat. If there is any “grab” or friction felt, you will need to wait longer for this coat to cure. Repeat the cure test every two-four hours until your fingers slip easily across the surface.

Using our products in conjunction with other exterior coatings:
Our Exterior Polymerized Tung can be used as a topcoat over another manufacture’s exterior stain if desired. It can be applied over water, alcohol or oil- based stains. If you are using other oil-based pigmented stains, you must make sure the surface is well cured prior to using our products and you will probably find some protracted curing times over another oil-based exterior product. You will need only 2 topcoats of Exterior Sealer over the stain.

Application Process:
All coats are applied with a good quality natural white china bristle brush or a synthetic water-based type applicator for decks. For maximum protection, do not wipe the surface until the last coat.
Note well: If you are using exotic hardwoods it is best to wipe all coats per #6 below rather than brush them on and leave them.

Wood Prep – final sanding to 120-150 grit. No higher to maximize saturation of Exterior Sealer. Vacuum the surface.

Brush out a thin, even, coat of Exterior Polymerized Tung Oil Sealer. Allow the surface to cure 24 hours.
Sand with 220 grit paper. Vacuum.
Brush out another thin coat of Exterior Polymerized Tung Oil Sealer. Use less Sealer with this coat. Cover the surface well with an even film. Allow the surface to cure 24 hours.
Sand with 320-400 grit paper. Vacuum
Working in sections that are approx. 3 ft wide by the length of the deck board areas – Brush out a thin, even coat of Exterior Polymerized Tung Oil Sealer. Wait 5 minutes and wipe off what is not absorbed. Move to the next section and repeat until the entire deck has been finished. Allow 24 hours for the surface to cure.
Maintenance

Wash the surface with detergent and water, rinse thoroughly and let thoroughly dry. If you have any mold on the surface, add 1 cup of Clorox per gallon of water.
Lightly sand with 400 grit paper.
Reapply a 1-2 coats of Exterior Sealer. If the surface needs two coats follow steps 4 -6. If you are applying a timely maintenance coat, 1 coat per #6 should be sufficient.

COVERAGE: Exterior Polymerized Tung Oil Sealer- 150-200 sq.ft /quart or 600-800 sq. ft/gallon Exterior Medium Lustre – 250 sq.ft /quart or 1000 sq. ft. /gallon after two coats of Exterior Sealer or stain.
EXPIRATION: Our Exterior products are most effective if used within a year of the manufacturing date. The manufacture date can be found on the bottom of every can.

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