Replies

1. 
   Gretchen | Jun 20, 2009 02:40pm | #1

   Probably need to really wipe it down well, and when "dry" top coat with a better finish coat like wipe on varnish.

   Gretchen
2. 
   JohnWW | Jun 20, 2009 04:58pm | #2

   Pure oil is a penetrating finish, it will never, no matter how many coats are applied, build up to create a film over the wood that will be shiny. If you want a shiny finish you need to be using shellac, varnish, lacquer, or an oil and varnish mix.

   Because of all the coats you have applied, there is a lot of oil in the wood and it may take a long time for the oil deep in the wood to react with oxygen to harden. Damp weather does seem to slow down the process. If the tung oil is truly pure, meaning that it has no driers added it may be very slow to polymerize.

   At this point you are stuck, you either have to be patient and wait for the oil to polymerize, which could take weeks or months depending on the oil's drying properties, or you could plane down the tops to remove some of the oil to speed up the process.

   Using a solvent to try to remove the excess oil may not improve things since the solvent will carry some of the oil even deeper into the wood.

   When the oil finally dries you will be able to apply a finish to get the look you want. You can take a chance and try to apply a film building finish before the oil fully hardens but there is risk that it won't adhere properly.

   John White
   Shop Manager for FWW Magazine, 1998-2007

3. 
   HowardAcheson | Jun 20, 2009 05:58pm | #3

   Pure tung oil is a very slow curing drying oil. We're talking a few weeks. It also will not produce more than a matte finish unless many coats are built up over time. Even then, it does not produce a surface that will stand up to the type of activity that the typical table top gets.

   You don't say how many coats of tung oil you have applied or how. If you have only a coat or two, I would recommend that you rub the surface with mineral spirits and a 4/0 steel wool. Rub in the direction of the grain and then use lots of paper towels to clean up the gunk. Let everything dry for a week or so.

   Now, consider what performance factors you want from a finish. If you want a "close to the wood" penetrating finish, I would recommend an oil/varnish mixture. Mix pure tung oil or boiled linseed oil, your favorite varnish or poly varnish and mineral spirits in equal amounts. Wipe this on, let it set for 15-30 minutes and wipe it dry. Let it dry overnight and then the next day do it again except use 4/0 steel wool to apply the mixture. Then wipe dry and let it all dry for couple of days. This should give you a warm, satin glow finish. Because of the varnish component, it will also provide some water and water vapor protection and some abrasion resistance.

   Another choice that will be more durable is to use a wipe-on, thinned varnish. Thin the varnish or poly varnish 50/50 with mineral spirits. Wipe it on using a lint free cloth or non-embossed paper shop towels. Wipe in circles like the kid at Denny's wipes your table. Do not soak the rag, it should be just damp. Let it dry until it is tack free and then apply another coat. Let this fully dry 24 hours and then flat sand with 320 paper on a sanding pad. Now apply two more coats just as you did before. You will now have a gloss or satin finish depending on the sheen of the varnish you used. This is a quite durable finish as you are actually applying a pure varnish finish.

   Howie.........
4. 
   gb93433 | Jun 20, 2009 06:41pm | #4

   Pure tung oil is basically like vegetable oil. When mixed with varnish it is much different. When it is mixed with varnish there must be enough drier in it for it to completely dry.

   http://en.wikipedia.org/wiki/Tung_oil

   
   

   ---

   Edited 6/20/2009 11:42 am by gb93433

5. 
   SteveSchoene | Jun 20, 2009 11:07pm | #5

   You didn't mention the time you allowed between coats.  It should be several days between each coat--at least--overnight is never enough unless your finishing space is really really warm.   

   In the end, it will never get more than really dull satin, even with 5-6 coats with sanding between each coat.  And, what do you get with 5 coats of pure tung oil.  Not much.  More resistant to water spotting than BLO, but more than nothing is still almost no protection.  So soft that you need to be dilligent in wiping off all excess of each coat.   

   At this point, you should wipe down with mineral spirits to remove any uncured oil on the surface, then, as Howard says, you should give it several weeks in a warm place to continue to cure.  After that, you can top coat with shellac, or oil based varnish--non-poly varnish would be my choice. 

   By the way, the Wikipedia article is all wet in a number of statements it makes.  Calling it a tough, highly water repellant, finish is really stretching the point. 

   The whole discussion how to apply it is wrong.  Wikipedia says:  The traditional technique is to apply the diluted oil as a succession of very thin films with soft non-fuzzy cloth like tee-shirt cotton.  This is how you apply a wiping varnish not how you apply an oil.  Oils you apply liberally to the surface, let penetratefor a short time, and then, before it starts to get tacky, thoroughly wipe off all excess material, leaving no apparent film on the surface.  Thinning the oil doesn't do anything to help this penetration process since thinner evaporates so quickly relative to the working of the capillary acton by which the oil penetrates. 

    

1. 
   HowardAcheson | Jun 21, 2009 06:52am | #6

   >> By the way, the Wikipedia article is all wet in a number of statements it makes. Calling it a tough, highly water repellant, finish is really stretching the point. Sounds like it was written by a packager of tung oil.Howie.........

1. 
   Gretchen | Jun 21, 2009 04:10pm | #7

   Which can be added to any Wiki article by anyone!! Grains of salt are often required when reading.  ;o)Gretchen

1. 
   forestgirl | Jun 22, 2009 12:22am | #14

   I tried to submit editing of a Wikipedia riving knife entry, but it was such a cumbersome process, I gave up.  Perhaps it was just a low-patience day. forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

6. 
   Rich14 | Jun 21, 2009 05:29pm | #8

   drsess,

   You say that you used "pure tung oil." Unfortunately, the confusion that swrirls around products that call themselves tung oil is huge and verges on fraudulent by manufacturers. There are many products which call themselves tung oil which have no tung oil at all!

   Knowledgeable furniture makers who want to use "real" tung oil have always stayed with manufacturers they knew to supply the "real" stuff. Real tung oil meant for furniture finishing has always been available as "partially polymerized." Tung oil is polymerized by heating. It reacts very little, if at all, to "metallic driers" and other catalysts commonly added to other finishing oils. Tung oil is often a component of oil mixtures and varnishes that contain metal catalysts that affect the other components in the mixture. Those driers don't accelerate the tung component, but because people have seen them listed together in MSDSs the idea has gotten around that tung can be catalyzed by drying agents.

   Tung oil that has not been partially polymerized (to one of several available "partial" conditions) is fairly useless for wood finishing. Non-heat-treated stuff hardens (not dries) so slowly, you'll grow old before the piece can be used. Pure, untreated tung might get firm enough after a year so that it doesn't actually feel sticky, but it will never achieve the hardness of a partially-polymerized, furniture-finishing-grade product.

   Against the fraudulent practice of calling any vegetable oil product, "tung" when there is actually no tung in it, manufacturers have gone about labeling real tung oli as "pure." Unfortunately, they have created further confusion doing this as some of them mean pure in the sense that there is nothing but tung oil in their product and others mean there is no solvent or catalytic additives. But they do not say whether their tung has been partially polymerized.

   "Pure" tung oil is still pure if it has been heat polymerized and even if it has solvents in it. As a matter of fact, all "pure" tung oil products recommend thinning with turpentine, mineral spirits or naphtha for applying to the wood.

   Get some partially polymerized tung oil and you will achieve the result you're seeking. Just do a Google search for "polymerized tung." I have no association with any suppliers, but here's an example of the kind of oil to use:

   http://www.leevalley.com/wood/page.aspx?c=2&cat=1,190,42942&p=20050

   Wipe down your table with with solvent (I prefer low odor mineral spirits or naphtha). Don't worry that you will drive the existing tung oil further into the wood. And don't use steel wool to do the wiping. The wood is not yet protected by any kind of film and steel particles will be driven into the wood fibers and they WILL rust later. Only use steel wool on film finishes that have hardened.

   Then apply diluted, pure, partially polymerized tung oil. It will penetrate somewhat over any residual oil and will set up in a reasonable time for a finishing schedule of about a coat every 2-3 days. Apply the first 2 coats with a rag, wiping the surface fairly dry each time. 3 days after the second coat, the surface should be hard. Subsequent coats can be applied gently with 4-0 steel wool which will burnish the somewhat-hard, but still-delicate underlying film as you apply. 4-6 coats will give a nice, medium luster finish. Give it a month to harden before real use.

   All that said, Tung is nowhere near as tough a table top finish as shellac, lacquer or varnish. It will degrade, if the table gets any kind of use. Of course, it's an extremely easy finish to "repair" months or years from now. Just get out your 4-0 steel wool, a fresh can of partially-polymerized tung and give it a coat or two. Good as new.

   Good luck,

   Rich

1. 
   Jimma | Jun 21, 2009 06:21pm | #9

   Rich -- you're right on with that advice. I learned about it the hard way after applying coats of pure tung oil (un-polymerized) to a cherry table. Fortunately, a neighbor's father who was retired from the cabinet business noticed my predicament when it wouldn't dry and came to the rescue with advice very similar to yours. Now, ten or twelve years later it's as great a finish as I could want and admired by many. Thanks for your thoughtful post. I hope it's broadly read.Jim MacMahon/Orlando

1. 
   Rich14 | Jun 21, 2009 07:21pm | #10

   Thanks Jim,(From one Floridian to another, withering in an unbelievable heat wave.)Rich

1. 
   Jimma | Jun 21, 2009 09:40pm | #11

   Yup, it's over 90 on my porch right now. Whew! Where 'bouts are you?

1. 
   Shoemaker1 | Jun 21, 2009 09:49pm | #12

   Thanks for that info. makes more sense to me.

2. 
   Rich14 | Jun 21, 2009 10:47pm | #13

   Crystal River. On the gulf coast, 80 miles north of Tampa.

3. 
   Jimma | Jun 22, 2009 01:20am | #15

   Know right where it is. Can't be hot there, it's on the coast.

4. 
   Rich14 | Jun 22, 2009 01:25am | #16

   98 today, still 93 at 6:25.