How to use Tung Oil

Here is a brief primer on how to use Tung Oil. These instructions also more or less apply to other drying oils such as linseed or hemp oil.

Firstly it should be said that natural drying oils have been used for centuries, possibly millennia, and there are few hard and fast rules for using them, unlike modern "plastic" coatings. Tung oil in particular has been used in Asia for eons. The process of applying Tung oil is kind of experimental. I will give some guidelines, but so much depends on the species of wood, previous coatings, level of sanding, temperature and humidity, etc, so take my recommendations and experiment with them!

Tung oil (and all drying oils) work by soaking deep into the grain of the wood and polymerizing, or hardening, in the wood. This is different than modern petroleum based finishes, which are primarily a "plastic" coating on the surface of the wood. This is why modern finishes eventually peel, blister, crack, and flake off, and have to be completely removed before reapplying when they fail! Tung oil on the other hand just fades a bit with age, and when it fades, you simply wipe a little more on with a cloth! It's that simple. The tradeoff is that drying oils produce a much more "dull" and rustic finish. If you like that (as I do) then you have a lifetime (or many lifetimes) of easy maintenance with your oiled wood.

Step 1:

- PREPARE the surface by removing previous coatings (other than drying oils), and sanding to the desired smoothness. (can also be applied on rough splintery wood, but will require more product). Make sure the wood is completely dry!

Step 2:

- APPLY tung oil with a lint-free cloth, paintbrush, standard paint roller, or varnish pad. It is best to flood the wood with lots of oil, as it will soak in!

Step 3:

- WAIT... let the oil soak into the grain of the wood. You could leave it an hour or two, or even overnight, but don't go too long, as it may start to polymerize! If you are applying in a dry warm environment the wait time is shorter than if you are in a cool humid environment. If you apply in direct sunlight, the tung oil may "FLASH POLYMERIZE" in as little as 10 minutes! This will cause all that residual oil to turn into a gummy mess on the surface... bad idea!

Step 4:

- APPLY MORE coats of tung oil until the wood stops soaking it up. ONLY DO THIS STEP IF THE WOOD IS SOAKING UP ALL THE OIL YOU FLOODED IT WITH.

Step 5:

- WIPE all residual tung oil off the surface of the wood. Any tung oil that is left will polymerize and become gummy = nasty.

Step 6:

- WAIT. Let the wood dry out a bit... a day or two?

Step 7:

- COAT AGAIN. Apply as many more coats as you want, making sure to give it time to soak in, wipe off all residual, and dry for a day or two in between coats. If you are applying to a very hard wood or wood with a very smooth finish, the first couple of coats can be cut 50/50 with a solvent such as citrus solvent, to allow better penetration into the wood.

I like to put 4-7 coats on hardwood floors, and most other wood items get 1-3 coats.

Other tips:

The final couple of coats can be buffed in between to improve luster.

For fine articles, quite a luster can be achieved by building up oil on the surface and buffing.

A very light sanding (400 grit? or extra fine steel wool) in between coats can improve the smoothness of the final product by removing fine hairs of wood that have raised.

Tung Oil fully cures/polymerizes in about 3 weeks at ideal conditions, however the surface is usually dry enough to use gently in a day or two.

VERY IMPORTANT NOTE:

Do not use a "tung oil" product made by CIRCA 1850, and expect it to perform as tung oil. It has a very small amount of tung oil, and the rest is petroleum based. Also, do not use linseed oils purchased from a general hardware store. They almost always are solvent extracted and have other chemicals and even heavy metals in them, plus too many proteins that will mildew in the final product. Always make sure your product is marketed as 100% pure tung oil, and for linseed oil, the company we recommend is Allback from Sweden.