Tung-Oil Based Finishes for Walnut Trim

Questions and answers about using Tung oil to finish trimwork on site. June 30, 2009

Question
I have a 5000 square foot house all done in walnut. The customer wants it finished natural with tung oil or something similar. I’ve worked with tung oil some, but only on small pieces. I’m trying to figure out a good way to finish this amount of wood without taking too long. Is spraying and wiping an option? Any ideas or articles you could point me to would be great.

Forum Responses
(Finishing Forum)
From Paul Snyder, forum technical advisor:
I'd use a product like Waterlox original. It's a tung oil based varnish that dries overnight and can be lightly sanded smooth and recoated the next day. Looks great and offers better protection than pure tung oil. You can spray and wipe if you want. I have done it many times, but only in a spray booth. The overspray with any oil-base finish product will take longer to dry than any of the regular spray finishes. As a result, the overspray will stick to stuff however far it travels before it settles. You could end up with overspray on the other side of the room (all over the big screen TV for example).


From the original questioner:
Thanks for your response Paul. I’m glad you mention the waterlox. The homeowner asked about that product. This is a new build, so overspray won’t be a problem. I’m wondering if painting the new drywall will be a problem with tung oil overspray on it, or will it dry enough to keep from bleeding thru the latex? How many coats of the waterlox would you suggest to look best? I did a couple samples on some walnut and it didn’t look that great after just two coats. I’m giving them another day to dry before putting a third coat on them.

Also, would the waterlox be a good product for the exterior of the walnut door? The paint store suggested Watco teak oil. Sorry for all the questions, I’ve done all my wood packages with precat lacquer, so this is all new to me. Thanks for your help.


From contributor T:
Waterlox is a minimum three coat finish, two original sealer and then a final of original sealer (gloss), or high gloss, or satin finish. It will look like crap until the third coat. You can do more coats for a thicker build but on tighter grained species like Walnut it’s not needed.


From contributor R:
I don't know if it can be used on trim, but I just used this product "Synteko Natural' for my walnut floors. I was contemplating using Waterlox tung oil, but liked the way Synteko formed a finish. It would be a challenge to apply by hand if you have a full library or a floor to ceiling wall system to do. My next suggestion would be a finish by ICA called 'Cerawood'. It looks and feels like a wax on finish, almost as if there is no coating on the wood.

From Paul Snyder, forum technical advisor:
Walnut is a dense hardwood and the finish doesn't soak into the wood the way it would with woods like pine, alder, cherry, etc. Depending on your application technique and the look the customer wants, you may need to apply as little as two coats or as many as four to five. After sanding the first coat smooth, you won't need to sand subsequent coats except to remove any further roughness or dust nibs.

Waterlox original isn't a good choice for an exterior door. You want a finish with UV inhibitors to reduce the sun's damage to the wood and the finish itself (UVAs and HALs). Exterior rated finishes are also more flexible so they don't crack as the wood expands and contracts with the changes in temperature and humidity.

No matter which exterior clear finish you choose, it will need to be sanded back and recoated on a scheduled basis to avoid failure. If the door is in direct sunlight, the time frame will be shorter than if the door is shielded by an overhanging roof. The amount of time can vary depending on the exposure and the product.

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