First off, I am in no way an expert, this is what I have found about using tung oil as a protective finish for wood and how I applied tung oil to wood.
Tung Oil has been around for many many years. It was used to preserve wood ships for hundreds of years. The oil penetrates into the wood, providing a relatively hard surface that repels water, giving it a waterproof finish. Another bonus is that tung oil seeps into the grain of the wood making the grain pop. In other words, the color of the wood is slightly darkened, giving the wood a rich, warm color or beings out the natural color of the wood. When tung oil is not thinned, in other words its 100% tung oil, it’s a non-toxic finish. Meaning it’s an ideal wood surface that can come in contact with food.
When using tung oil make sure you are buying 100% tung oil, if it doesn’t say it’s 100% don’t buy it because it has already been thinned.
How to apply Tung Oil to Wood:
Like any project there is always the preparation step which should never be skipped. The wood should be free of oil, dirt, grease and any other contaminates. Tung Oil can not be applied over any other finish (vanish), it can only be applied to a previous coat of tung oil. To give you the best result of a previous finished surface, the surface should be stripped then cleaned with TSP (Trisodium Phosphate) and then sanded.
Since tung oil will highlight the wood grain, it will also highlight any blemishes and scratches that are on the wood. Therefore, take your time to prepare the wood by sanding before applying the oil.
Here is my project all ready for tung oil.
- Applying Tung Oil:
As with any traditional product that has been used for many years, there are many different opinions on how to apply tung oil, this is just how I did it.
Use a clean, lint-free rag to apply tung oil. Apply a small amount of oil to the cloth then apply by rubbing along the grain of the wood. Do not starve the wood, meaning you should not have to rub hard or often to get the wood wet. If you are, then re-oil your rag. But you don’t want over saturate the wood either, meaning the wood should be wet but not forming puddles. If there are puddles, remove them by wiping.
After letting the oil sit for 30 minutes to an 1 hour, rub the wood with a clean rag to remove any excess oil.
Let the wood sit for at least 24 hours, or until the oil has absorbed into the wood. Because guess what it may take weeks for the wood to fully dry.
My project after first coat of tung oil.
To obtain a super-smooth finished, rub the project surface with 0000 steel wool in-between coats or you can also use #600 grit waterproof sandpaper to apply the next coat, this is what I did.
Applying second coat, if you notice I poured the oil directly on the wood but it got into the cracks of the wood, making it take longer to dry in-between coats.
To get the maximum protection, apply 3 coats of full-strength tung oil but you can always apply more. I applied more coats until the oil was not penetrating into the wood after letting it sit.
As an optional step, you can thin the first coat of tung oil by 50% oil to 50% mineral spirits. This will greatly increase its penetration into the wood. But if the oil is thinned, the project will no longer be food-safe!
Repairs for projects finished with tung oil are pretty simple. Just follow the same steps as the original application. Rub the damaged area with the tung oil, let stand, then wipe off any excess. But again to get the maximum protection, apply 3 coats of full-strength tung oil to damaged area.
My finished project after applying 4 coats of oil and painting the sides. I just love how it being out the natural color of the wood.
I have heard of people using a stain and then applying tung oil but I have not tried this method. Hope this helps if you are looking at using tung oil to finish your wood project.