How to apply tung oil to your wood projects
If you’re looking for a natural, food-safe finish that brings out wood grain and gives a warm, satin sheen, tung oil is a top choice. In this post, we’ll dive into the process of applying a tung oil finish, covering the standard and wet sanding application methods, how to thin tung oil, and how to maintain that warm, glowing finish.
What is Tung Oil?
Tung oil is an oil extracted from the seeds of the tung tree, which is native to China and parts of Asia.
Unlike other wood finishes, tung oil is a natural drying oil penetrating deep into the wood fibres rather than just coating the wood surface. This penetrating quality allows tung oil to enhance the grain patterns and texture of the wood, resulting in a beautiful, warm finish.
Benefits of Using Tung Oil
One of the key benefits of tung oil is its durability and water resistance. As it cures, tung oil forms a flexible, moisture-resistant film that protects the wood from wear and tear (but scratches on top can still occur; it’s not a bulletproof finish).
This makes it an ideal finish for wood furniture requiring a warm satin glow. Additionally, tung oil is food-safe, non-toxic, and free from harsh chemicals, making it an excellent choice for environmentally-conscious woodworkers or those needing a safe product for cutting boards and counter tops.
If you want to know more about the pros and cons of tung oil, take this deep dive.
Differences Between Pure Tung Oil and Tung Oil Finish
In my recent experiments in the workshop, I looked at the application process and final look of 6 different oil-based wood finishes. This included a Pure Tung oil and a Tung oil finish.
Pure tung oil is, of course, 100% tung oil with no additives. A tung oil finish is a blend of different oils and solvents to assist in drying time. Due to the additives, a tung oil finish is often no longer food-safe.
The choice to use pure tung oil or a tung oil finish will depend on the goal of your DIY project. Require additional information? Check it out! The rest of this post will look specifically at the application process of pure tung oil.
Preparing for Tung Oil Application
Wood oil finishes have a standard application process. This involves applying the oil, waiting the required time, wiping the remaining oil off, and allowing the necessary drying time before subsequent coats. It’s relatively straightforward. Let’s look into the process and tools needed with tung oil for this standard application process.
Choosing the Right Tools and Materials
Before starting your tung oil project, gather the necessary supplies. You’ll need:
100% pure tung oil – which provides a durable and water-resistant finish.
Lint-free rags – These will apply the tung oil and remove excess. I always recommend having clean cotton rags available in the workshop.
Foam or bristle brush – An alternative to rags for applying the tung oil, especially on larger surfaces.
Sandpaper—If you plan to use the wet sanding method, you’ll need 320-400 grit sandpaper for a smoother finish.
Tack Cloth – remove any dust and dirt before applying your tung oil.
Gloves – protect your skin!
Wood Surface Preparation Before Applying Tung Oil
Before you even think about applying tung oil, it’s crucial to properly prepare the bare wood surface. This involves sanding the piece of furniture with progressively finer grits of sandpaper, starting with 80-grit and working up to 220-grit or higher. This step ensures a smooth surface for the tung oil to adhere correctly, and it’s a key part of achieving that beautiful, warm finish.
Once sanding is complete, thoroughly wipe away dust or debris with a tack cloth. This step ensures a smooth surface for the tung oil to adhere correctly. You want your furniture surface to be clean, bare wood that is sanded smoothly. The satin gloss finish of the tung oil will highlight any sanding swirls and colour differentiations.
Need sanding help? Read these handy tips!
Let’s examine the two most common techniques for applying tung oil: the standard application method and the wet sanding method.
Standard Application Method
The standard application method is the process used for nearly all wood oil finishes. It is the process which is advised by the manufacturing companies.
Applying the First Coat
Apply a thin coat of tung oil using a lint-free rag, foam brush, or bristled bush, working in the direction of the wood grain. Allow the oil to soak into the wood for 15-30 minutes, penetrating the wood fibres.
After the required time, remove excess oil from the surface using a clean, dry rag. This is oil that has not penetrated into the wood fibres. If not removed, it will dry sticky on the surface of the wood, ruining the finish of the piece of furniture.
Thinning Tung Oil
A common practice among woodworkers is to thin the first coat of tung oil. This is done by taking your tung oil (place a small amount required for the first coat into a separate jar) and mixing it with 1 to 1 solution of the tung oil and white spirits. The opinion is that the tung oil and white spirits (mineral spirits) will help the first coat penetrate the wood fibres more quickly and then dry off.
However, if you opt to try this method of thinning the first coat of tung oil, be aware that adding the solvent white spirits makes your finish no longer food-safe.
Drying Time Between Coats
After applying the first coat of tung oil, it’s crucial to let it dry properly before adding additional coats. The general rule is to allow 24 hours of drying time between coats. The oil penetrates deep into the wood fibres during this period, creating a long-lasting and durable finish.
Drying vs Curing Time
Drying is the time required for the tung oil finish to feel dry to the touch, after which another coat can be added. Hardening or curing is when the tung oil has gone through the process of polymerization, resulting in a durable and solid finish.
Additional Coat Application
After allowing the first coat of tung oil to fully cure for at least 24 hours, you’ll want to apply 2-4 coats using the same process.
Sand the surface lightly with 320-400 grit sandpaper and wipe away dust with a tack cloth before applying each new coat. Apply the tung oil in a thin, even layer. Allow it to soak in for 15-30 minutes, then wipe off excess oil. Allow 24 hours for the drying time before the next coat.
By adding multiple coats, you can achieve a durable finish, but many woodworkers swear by a minimum of 4 coats to achieve that tung oil satin glow.
Wet Sanding Method
The standard application method is listed as the manufacturer’s recommended application method. However, there is another process, the wet sanding method, which is also commonly used with tung oil. It’s used to achieve a smoother surface and to fill any wood grain.
What is Wet Sanding?
Wet sanding is the process of sanding a surface with ultra-fine sandpaper and water or, in this case, oil. The oil will mix with the saw dust developed by sanding and create a paste which will fill any wood grain that is not already sanded sealed.
Wet Sanding Tung Oil Application Process
When the wood is prepared and cleaned, apply your tung oil with a bristle brush, rag, or foam brush. Rather than allowing the oil to sit for 15 to 30 minutes, take a piece of 320 or 400 grit ultra-fine sandpaper and lightly sand with the wood grain.
The sanding process will create a slurry with the sawdust and the tung oil. This slurry will fill the remaining wood pores as you continue to sand. I’m not going to lie. You need to sand for awhile, probably the 15 minutes to get the full effect. Afterwards, you can clean your surface of any remaining oil and slurry and allow the wood surface to dry.
Several coats of the wet sanding method will fill in any remaining wood pores and create an incredibly even and smooth surface.
Visual Learner?
Full Cure Time of a Pure Tung Oil Finish
While tung oil dries in about 24 hours between coats, it takes much longer to fully harden or cure. It will depend on how many coats of pure tung oil you have added to reach fully cured, which will take 30 days on average. Once fully cured, the oil polymerizes and hardens into a durable, water-resistant finish.
It’s essential to allow the full 30-day cure time before using the tung oil-finished piece or subjecting it to moisture, heat, or heavy wear. Using the object too soon can lead to a sticky surface or other finish defects. Patience is crucial in allowing tung oil to reach its full potential as a long-lasting, beautiful wood finish. This extended curing time is considered the con of a pure tung oil finish.
Tung Oil Rag Disposal and cleaning your tools
As you admire the satin finish on your furniture, remember that the tung oil application has one final, essential step: properly disposing of your oily rags and cleaning your tools.
Safety is key for your rags. As oil dries, it heats up and can spontaneously combust (catch on fire!) if not cared for correctly. Therefore, I take all my rags and immediately soak them in water before storing them in a sealed metal container (think old paint container that has been cleaned) with water until you can dispose of them responsibly at your local hazardous waste facility.
Now, for your brushes, treat them to a cleansing white spirit bath to dissolve the tung oil. Swirl the bristles gently until all traces of oil are removed. Follow with a warm, soapy water rinse until the water runs clear and there is no oily feeling. Then, lay them flat to dry.
Maintaining A Tung Oil Finish
Regular maintenance is vital to keeping your finished piece of tung oil looking its best. First and foremost, dust frequently with a clean, dry cloth to remove any surface debris. Every 12 months, it’s recommended to reapply a fresh coat of tung oil. This will help rejuvenate the finish and keep the wood properly nourished.
How to Care for Tung Oil Finished Surfaces
For deeper cleaning, use mild soap diluted in warm water. Never use commercial solvent-based cleaning products, as these can also degrade the finish over time. Dip a cloth in the warm water and mild soap solution. Squeeze out excess water and lightly wipe the wood surface with a damp cloth.
If the finish looks dull or worn, refresh it by wet sanding with 400-grit sandpaper and a tung oil/mineral spirits mixture. This will remove any built-up grime and prepare the surface for a new coat of pure tung oil.
Reapplying A Tung Oil Finish
Reapplying a tung oil finish is as simple as applying it previously. Apply the 100% tung oil to the surface and allow it to dry for 15 to 30 minutes before wiping off the remaining oil. Provide a full 24 hours of drying time and determine if you require any additional coats of tung oil.
Final Thoughts
Applying a tung oil finish to your woodworking or furniture refinishing projects is a rewarding process that results in a beautiful, natural look. Tung oil penetrates deep into the wood grain, enhancing its natural character while providing a durable, water-resistant coating. By following the steps outlined – properly preparing the surface, applying thin coats, allowing sufficient curing time, and maintaining the finish – you can achieve a rich, warm patina that will last for years.
