tung oil advice

[Colin Dingler]

I'm using tung oil for the first time and could use some advice. My project is to finish some walnut countertops. I have read a number of discussions online about methods for finishing with tung oil, and my sense of the general process is:

• sand to around 150 grit
• start with oil that has been thinned with an organic solvent (I just applied my first coat with a 2:1 ration of MS)
• apply liberally and wait for it to soak in, then reapply over dry spots
• after an hour wipe off any extra oil
• wait 1-2 days and then sand with 0000 SW or 400 grit sandpaper
• repeat for 3+ coats, decreasing the ration of solvent to oil in each application

I know that the details for this process vary. I'm a little unclear about the sanding part. Is there an advantage to sanding with with steel wool or 400 grit? Do I wet sand with the next coat of oil, or should I clean the surface after sanding?

My other questions are about wood filler. I used an oil-based filler to fill many imperfections before I started. When I sanded the surface with 150 grit before applying the first coat, I thought that I had sanded off the filler. However, once I applied the oil I could see a residue of the filler around the holes--it looks like some of the filler was left in the grain of the wood in the splotch where I had left the filler to dry. Now that I have put a coat of oil onto the surface, what should I do? Can I sand the surface again with 150 to get out more of the filler residue and then continue with another coat of the oil?

Also, there are some imperfections that popped out after I applied the oil. These are little cavities at the pieces where the joints of walnut are joined together. Honestly, the counter (from Lumber Liquidators) has quite a few rough spots. Can I apply more filler to the surface after I've already put on a coat of oil?

thanks for any advice you have to offer.

[Jim Becker]

Fillers are not really a great thing when you are using a penetrating oil finish...they are going to stick out because the oil goes around them.

If you are using "real" tung oil, there's no harm in additional sanding to smooth your surface. Sometimes sanding is used to "naturally" fill small pores when a drying oil is employed which results in a smoother surface for obvious reasons. It's also quite normal to sand to finer levels when using an oil finish.

'Just as an aside, do not expect that your oil finish is going to protect those counters long term from water issues. It will not. Even with a dozen coats...

[Colin Dingler]

Thanks for the reply. The point about protection from water is interesting--I have heard both sides on this. I spoke to a woodworker who runs a local business and he told me that he has wooden counters finished in tung oil that he's used for years without any water damage around the sink. I've heard the opposite, too. It's curious that there are such divergent opinions on something that seems like it should have an objective answer.