How to Apply Tung Oil Properly -Tips & Techniques

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Pure Tung Oil enhances wood by accentuating its grain and adding depth to its patterns. Here is a step by step guide to applying Tung Oil the right way. 

Wooden Kitchen Counter Top

Tung oil protects, nurtures and beautifies wood like no other finishing product available. It is my all-time favorite choice for finishes that don’t require rock-hard protection offered by clear surface coatings such as polyurethane, lacquer and shellac.

Pure Tung oil is the perfect choice for food preparation areas because it is a eco-friendly, green, natural product without additives. It is known for its longevity, durability, and easy reparability. It is impervious to water and most other liquids. Unlike a lot of natural oils it is impervious to mold, it won’t darken with age and it won’t become rancid. Plus, it enhances the wood’s natural grain patterns. By comparison, no other finishing product can come close.

Like all oils, Tung oil is flexible so it moves easily with woods natural seasonal expansion and contraction. Like all other oils it can be easily repaired when damaged. Unlike most other oils and top coats in its pure form it contains no harmful VOC’s or other chemicals.

NOTE: Tung oil is sold as PURE TUNG OIL, POLYMERIZED TUNG OIL and a variety of TUNG OIL FINISHES. The “FINISH” variety or any Tung oil product not labeled as “PURE” has been hydrolyzed or contain additives many of which are petroleum based. All are done to enhance speed of application, drying times and in many cases manufacturer profits.  Many of the additives emit VOC’s (Volatile Organic Chemicals) so they are no longer an eco-friendly, green product nor are they “food safe”. Some are blended with polyurethane for added durability. I’ve heard that some purveyors of Tung oil don’t have any actual Tung oil in it.

I’m not saying that these products are bad but if staying green and you want the beauty and benefit that a “pure” Tung oil product delivers then use care in your selection process and know what you’re actually buying. While I do recommend thinning the oil it can be done with citrus-based solvents rather than paint thinner or mineral spirits keeping the finish VOC free and green.

Tung oil comes from the seeds of the nuts from the Chinese Tung tree, so if you have a nut or seed allergy proceed with caution, it may not be the best choice for surfaces or utensils that will be in direct contact with food. While there is a lot of debate concerning the possibility of nut/seed allergy there are other oil finish choices where food safety is an issue. For this reason, I don’t recommend it for cutting boards, wooden utensils and wooden serving dishes and bowls.

The other popular wood finishing oil is Boiled Linseed Oil and it has a ton of woodworker and finishing fans. The biggest advantage is speed of application and cost. I will cover that in my next article.

Tung Oil Advantages

That said here’s the advantages of Pure Tung Oil. There are no chemicals added, it hasn’t been polymerized or hydrolyzed, it won’t yellow with age, it doesn’t turn rancid, it is mildew resistant, it’s one of the few oils that hardens completely and stays flexible after hardening and it is waterproof. Tung oil has been used on boat decks for years, and is now becoming a popular wood floor finish. Lastly, while all finishes can be damaged with Tung oil any damage is easily repaired.

Tung Oil Disadvantages

There are a few downsides to Tung oil. It costs more than many other oils, it dries slower so takes additional time between coats. This can be a few days with proper temperature and humidity to weeks in cold, humid conditions. Polymerized Tung Oil has been super heated changing it’s chemistry slightly. Polymerization allows for drying overnight. I recommend thinning both and 5 coats. That said, if beauty combined with function and durability is what you are after Tung oil should be at the top of your list.

Tung Oil Coverage

A gallon of Tung oil will cover 400-500 square feet but since we will be thinning it and applying multiple coats 2.5-3 gallons is recommended for that area dimension.

What you should have on hand before starting:

New Wood – 2 Grades of Sand Paper (120 – 180 – 220 – 320 – 400)
Old Wood or Damaged Wood Surfaces – 3 Grades (80-120-180 – 220 – 320 – 400) and a mechanical sander
Tack Cloth
Latex Gloves
Applicator (choose one)– (Cotton Rag – Natural Bristle Brush – Foam Brush)
Pure Tung Oil
Thinner: Either mineral spirits or an eco-friendly citrus based thinner
Suitable mixing container
Clean rag for wiping excess
Mineral spirits (Oil stains only)

Proper Tung Oil Application and Surface Preparation

Oils, unlike clear surface coatings polyurethane, lacquer and shellac (from here in I will refer to them as surface coatings), should be finish sanded anywhere from 320 to 400 grit sandpaper. Surface coatings will hide 180 grit sandpaper scratches whereas oil will accentuate them. So when oiling wood a finer finish sanding is highly recommended.

Raising Woods Grain – A necessary Step for a Fine Finish

Think of prepping wood for finishing like getting a haircut. The first wash after your barber visit results in a whole bunch of split ends that suddenly pop. Well wood fibers are a lot like hair strands. After all the sawing, gluing, planning and sanding many of the wood fibers are damaged and torn. Adding moisture (like shampooing your hair) pops those broken strands and they need to be removed for a really nice finish.

For that better finish the grain should be intentionally raised before staining or finishing. I always wet my woods after my 180 grit sanding (for a complete sanding explanation see my YouTube videos Sanding Efficiently <for beginners>, and Choosing the Right Grade Sandpaper for Your Woodworking Project <for all levels>). Wetting the wood raises its grain (kinda like split-ends in hair) which can be sanded down with the last or next sanding of 180 or 220 grit papers.

Raising the Grain entails wetting the wood’s surface, letting it dry and then re-sanding to knock down raised wood fibers. You can use a spray bottle or a wet rag to moisten (not soak) the surface. Let it dry and then come back and sand or re-sand with a 220 grit sandpaper (if you are staining or applying a surface coating use 180 grit to level the grain).

Thinning “PURE” Tung Oil – The Proper Way

Surface Coatings (polyurethane, lacquer and shellac) lay on the surface of the wood. Oils penetrate into the wood surrounding and lubricating layers of the woods structural fibers and filling its pores. Tung oil will require a minimum of 5-8 coats with many woodworkers moving well into the teens. Future coats will gravitate close to the depth of the last coat, building on its depth, durability and appearance.

The less viscid (thinner) the oil the easier and consequently deeper the wood absorbs that liquid. Based on that we are going to shoot to get the oil as deep as possible into the woods underlying fibrous layers. Since most oils in nature are thick and viscid we will thin our first coat by 70%  (7 parts thinners to 3 parts Tung oil).

Future coats will be thinned as follows:

  1. First Coat – 70% (7 Parts Solvent to 3 Parts Tung Oil)
  2. Second Coat – 55% (51/2 Parts Solvent to 41/2 Parts Tung Oil)
  3. Third Coat – 40%  (4 Parts Solvent to 6 Parts Tung Oil)
  4. Fourth Coat – 25% (1 Part Solvent to 3 Part Tung Oil)
  5. Remaining Coats – 0%  (No Solvent)

As I mentioned, future coats will gravitate close to the depth of the last coat, building on its depth, durability and appearance. Thinning can be accomplished by adding paint thinner, mineral spirits or naphtha. All are petroleum-based products that emit volatile organic chemicals (VOC’s) during the application process and for a period of time afterward.

Eco-friendly Tung Oil Thinners

If additives and VOC’s are a concern for you and your family then citrus based thinner solvents are readily available and can be used with the same ratios listed above.

Mix the oil and solvent in a jar, bowl or clean squeeze bottle type container.

Applying Pure Tung Oil – Properly

TIP: It’s always best to get the feel of any procedure by practicing in an unnoticeable area like the bottom of a table, the back of a dresser, the inside of a cabinet, etc. I’ve done thousands of projects over the last 30 plus years and “ALWAYS” follow this rule on every one of them.

Tung Oil can be applied with a natural bristle brush, a foam sponge type brush or a clean cotton rag. If using a cotton cloth swatch (old T-shirt material is perfect), fold it into a pad so there are no cut edges with hanging threads touching your surface to be finished (to avoid thread tear).

Start with the hardest to reach spots first to avoid contact later in the application. Apply following the grain of the wood. The object of the first coat is to saturate the wood as deeply as possible.

Apply a generous but controllable amount of Tung oil to your applicator especially for the initial few coats. The surface should look very, very wet but not puddled. The thinned oil should soak in rather quickly to kiln dried wood. Older and reclaimed woods will suck it up like a camel in the dessert. All areas should look wet but if any areas have standing puddles spread them out or wipe them off.

On the flip side if your wood sucks in your application, reapply again and again keeping the surface wet (but not puddled) with oil for the next 30 minutes. After 30 minutes your wood should be saturated with oil and any excess wiped off.

Watch for the next couple hours and if any excess oil has bubbled to the surface wipe it off. At this point allow to dry before applying the next coat.

Re-application Timing – The Pitfall of Tung Oil

As I mentioned earlier there is no more beautiful finish to a wood surface than Tung oil provides. That said, there is a trade-off and that trade-off is drying time and layering of coats. Lacquer can be reapplied within minutes and the complete project with multiple coats completed in less than a day (the reason most mass produced furniture is lacquered). But the appearance of a lacquer finish doesn’t come close to a properly done Tung oil finish. After the initial and subsequent applications you should wait 2-7 days before sanding and reapplying.

Wait time is based on how quickly the surface dries. This is a factor based on temperature, humidity and thickness of the coat. Since early coats have been thinned they tend to dry much quicker (see sanding between coats for timing). If taking a 10-45 days to complete your project is unreasonable and you still want close to the appearance of a pure Tung oil finish, you could switch to a polymerized Tung oil finish product (not pure Tung oil) or to boiled linseed oil (BLO), both cut finish time substantially.

Polymerized Tung oil has been heat treated and additives that speed drying times added. The downside to speed is appearance. Pure Tung oil gives off a deep, rich, matte-like finish. It really accentuates the grain patterns and adds depth to your wood’s surface. Polymerized produces a more shiny, reflective surface.

Tung Oil Re-coating – Sanding Between Coats

Typical dry times are between 2 and 7 days before re-coating. You can test to see if the surface is ready to be re-coated by doing a light sanding in a small area with a 400-600 grit sandpaper. If the sanding produces a fine white dust you are good to go. If on the other hand it turns gummy and clogs your paper the surface is not dry enough for re-coating.

Between coats just before apply your next coat do a very lite sanding following the direction of the grain (operative word is lite as we don’t want to cut through the very thin layer we just put down previously). Use either a 400-600 grit sandpaper, a #0000 grade steel wool, or a grey scotch brite pad (grey pads are rated 400-600 grit).

Applying Tung Oil – The Final Coat

Your final coat(s) of Tung oil should be applied full strength. Don’t sand the final coat. I allow it to cure and then depending on the look I am looking for I might apply a coat of paste wax. Paste wax on wood is just like paste wax on your car. It offers minimal protection but adds depth and smoothness to your wood project. Please avoid waxes with silicone additives. Silicone (like WD-40) adds a slippery texture that feels nice to the touch but fouls refinishing coatings and becomes an absolute bear to remove should you ever decide to touch-up or refinish your project.

Tung Oil Repair

You won’t believe how easy this is. Clean the damaged area, apply pure Tung oil undiluted to a soft cotton cloth and wipe it on. If it soaks it up quickly apply a little more and repeat until the wetness lasts for 30 minutes. After 30 minutes, with a little elbow grease, rub the Tung oil into the damaged area for a few minutes. Wipe any excess and you’re done.

Tung Oil Rag Disposal

Oily rags are volatile and should be hung to air dry. Rags have been known to spontaneously combust when balled up in a refuge container.

Tung Oil – Dry vs Hardening

Tung oil dries in a few days and can be put in moderate service. Tung Oil does not fully cure or harden (dry all the way through) for 30-45 days. It’s okay to put your project in service once dry but you should refrain from heavy use until hardened.

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