Tung oil over Urethane?

[SteveKoz]

Looking at a fireplace mantle. 4" thick slice of a tree.  The lady that made the mantle said she urethanes them first and then applies 2 coats of Tung's oil.  She said it gives it a smoother finish.  Didn't want to get into it with her so thought to come here.  My understanding, once you urethane a piece of wood that wood is sealed.  Tung's oil will just sit on top of the urethane until you wipe it off.  If you don't wipe it off it will become sticky.  Is my thinking correct?   Is there ANY benefit putting Tung's over Urethane? 

[gee-dub]

I would not do that.  I wonder if she reversed the description when she was talking to you(?).

[SteveKoz]

Would there be any benefit of putting Tung's oil on IF the plan was to Urethane over it?

[Tom King]

Makes no sense at all.

[wtnhighlander]

A lot of folks feel that oil brings out the color and grain, then they follow with urathane for durability. Personally, I think a simple wipe-on urathane has exactly the same appearance.

I certainly can't see any advantage of putting oil on top of poly.

[Coop]

On 4/5/2023 at 7:56 PM, wtnhighlander said:

A lot of folks feel that oil brings out the color and grain, then they follow with urathane for durability. Personally, I think a simple wipe-on urathane has exactly the same appearance.

I have an uncle that does the same to his rifle stocks and like you, not sure why. 

[Chestnut]

Be aware that Tung oil finish can be a various number of different things. It's a marketing term and means next to nothing. If it's not labeled 100% tung oil it's likely a blend of oils and varnishes (urethane). Depending on the mixed used it may not be a problem.

With out knowing the exact brand and products used it's hard to say if it's a bad idea.

Reference: (https://www.thisoldhouse.com/woodworking/21015659/how-to-pick-tung-oil-finishes) I have way more references if your interested.

That said tung oil is a curing oil and even though it may not penetrate significantly into the surface it will cure on the surface. I've been using 100% pure rung oil a bit lately and it's a good curing oil. Applied with a good technique over urethane it may result in an exceptional surface. I'd let the results speak for them selves over the description of the products used. If the finish is not sticky and feels smooth what does it matter?

[SteveKoz]

Not sure why it really matters to me.  Guess I like knowing what I'm buying also I like the learning aspect of it.  Like I said, if there is ANY benefit doing so I'd like to know so might apply to a different project. 

 

 

[Chestnut]

The benefit I see is that urethane can be difficult to apply if it's a thick brushing formulation. Using a tung oil finish aka wiping varnish you can add some extra coats after sanding to achieve a very smooth uniform surface finish. These finishes are sold under multiple marketing names like Tung oil finish, Danish Oil, Teak oil finish, Wiping Poly, Wipe on Poly etc.

This isn't much different from applying 5-6 coats of wiping polyurethane. You are just substituting a few coats of wiping with a thicker brushing poly.

That is if it's tung oil finish. If it's 100% pure tung oil I'm not as sure but would be similar to comments above just a bit more confusing.