Hi. I am a TOTAL newbie! I’ve never stained or finished anything or, for that matter, even sanded wood. But I’ve taken on the task of finishing some unfinished walnut butcher blocks with tung oil.
Two days ago I applied one (the first) coat of 70% citrus solvent with 30% pure tung oil.
Last night it was still tacky. Today it is smooth but a *little* sticky. When I rub my hand across it, it comes away with an oily sheen.
Is this normal and I just need to wait longer?
Does this mean I applied it too thick?
Or do you think I rubbed too hard with the tack cloth and that it’s beeswax?
Any help would be appreciated!
Monica
Replies
Also, on one of the pieces of wood that is still unfinished, I tried to fill in some cracks and holes with wood filler and a putty knife. I think this was a mistake as I wasn't able to get the filler off of the area around the holes. I scraped hard with putty knife, wiped with both wet and dry rags, and sanded and it's still obvious that a hole was filled. (See pics)
Fortunately, this was on the bottom side of the countertop, but if there are holes on the top side, should I even try to fill them?
Again, thanks so much!
Ok....putting on my chef's hat where I got training from the Culinary Innstitute of America in Hyde Park NY....I use ONLY medicinal mineral oil on my boards....it is food safe....have concerns over the use of tung oil on a butcher block.
Thank you for replying!
From what I've read, pure tung oil is food safe. Some of the cans that say they are tung oil are mixed with turpentine and other solvents that aren't safe though.
That's why I chose to mix the tung oil with citrus solvent. That is also food grade safe as far as I know.
You are correct, 100% tung oil is food safe. It's actually better than mineral oil in that it penetrates the wood and adds a degree of water resistance. Mineral oil largely remains on the surface and doesn't dry, that's why you have to keep reapplying it. Tung oil does take a while to dry and you need to wipe off the excess, which I'm guessing is your problem (along with the solvent). That said, I use it straight without any solvent. Wipe on a heavy coat, there's no need to flood the surface and wait half an hour, you'll just wipe it all off. If there are any areas that soak up the oil quickly, wipe on some more. After a few minutes, wipe off whatever is left on the surface. As it initially sits, there's a good chance you'll see oil reappear on the surface. Wipe it off. After about a few days at room temperature it should be dry enough that you won't get greasy hands touching it. I keep wiping regardless. I'd give it another week before adding a topcoat if that's your intention.
I wouldn't strip what you've got. Keep wiping it down with clean cotton rags and wait for it to dry. The warmer the space and less humidity the better. I put small stuff in an old upright freezer that I converted into a heat box to dry faster.
As for the wood filler, glad you only used it on the bottom. Use that stuff for patching small holes when you intend to paint, at best. You should be able to sand it smooth. Are you using a block or pad to back your sandpaper? For filling visible holes it depends on their size and if you want to accentuate the patch or hide it. Easiest is sanding dust mixed with regular wood glue, e.g., Titebond. Mix lots of dust with the glue and fill the hole. You can also fill the hole with sanding dust and drip in CA glue (crazy glue). Both will need to be sanded and you'll definitely need to do the latter in layers. You can also get thick, black CA glue, if you want a black crack. It can look nice depending on the wood you're fixing. Both methods are better for small defects. Big cracks or knot holes can be features, i.e., left alone, or you can stabilize them using epoxy mixed with either sanding dust (isn't the best for hiding stuff) or a powder made for tinting epoxy (I personally like a green-blue). You can use just about anything to tint epoxy. There are tints specifically made for it, or you can go to the dollar store and get the powders used for eye makeup, literally. Just do a trial before committing to wood. You can also use wood patches, aka Dutchmen, to either accentuate or hide a defect. Google that one as I've already gone on too long. Hope this helps and welcome to the club. Not only is woodworking one of greatest rabbit holes to go down, you'll meet a lot of really great people.
Gosh, this is all so helpful History Dude! I didn't realize that I could keep wiping it this late in the game. I thought it might gum it up even more.
And thank you *so* much for all the information about the holes. That gives me lots of options.
I have made many cutting boards and here's what I've done - my favorite finish is a 4 to 1 mix of mineral oil and beeswax. Straight mineral oil is fine too, just doesn't totally dry. You could go with a 3 to 1 ratio. Some have used cold pressed flaxseed oil. Pure tung oil is said to be food safe(I don't use it), however it seems to be giving you trouble. As for the filling of the holes, looks like it's a color match issue. When filling you want to use material that will not come loose at some point - I use Mohawks epoxy putting fill sticks, they come in many colors. You cut off a piece and mix with your fingers and then fill. They are not cheap, but the fill is essentially permanent. The filler that you have used I would guess is something from the home center and they will not hold up to repeated washing and use.
I'm committed to tung oil, so am interested in what to do at this point.
Thank you very much for the info on the Mohawks epoxy. That seems like it might be easier to fit *only* in the hole without getting on to the rest of the wood.
Getting to pick the color would be very helpful too!
No expert, but have made a lot of cutting boards. So you put on a thick coat, but how soon did you wipe it off? It's best done sparingly. Tung oil can take up to 30 days to cure (not dry). But if thick, I've only seen it gum up. I don't see how the solvent will change that. But for cutting boards, they are going to get a lot of wear from knives, etc., which oil doesnt really protect much. So to me the goal of a finish is to be regularly re-coatable. I use a mix of beeswax and mineral oil as well,
I think I may have put it on too thick.I didn't realize how aggressive you need to be about wiping it all off the surface between applications.
You said you've only seen it stay gummy (forever?) if too thick. How long did you wait when it was too gummy? If it can take up to 30 days to fully cure, I hope I don't have to wait that long only to find that it's still gummy!
So far it's been 3 days.
Scrape it off agressively. Assuming you are in the USA, it's heating season, so put it in the boileroom for a week. Sticker it or hang it on a string. What you have in a week will dictate next steps. Your goal is a full cure of what you've already applied. Overall, I am in the mineral oil & wax camp for cutting boards.
@_mj_ I am doing large butcher block countertops, not a cutting board, so I can't hang it, but I'll crank up the heat in the house.
I did another one today and was more sparing with the tung oil and it is already starting to dry after just 8 hours.
I think the first might be too, just muuuuuch more slowly. (Maybe)
@StanTheMan - Do you think the gummyness of the first one would go away by or before 30 days?
Newbie - I dont know but I would think once you have a gummy "film" it won't "harden" because it's just oil. That is, it hasn't adsorbed to the wood, so its just a thick layer of oil that not become a hard layer of film finish like varnish or shellac.
Pure tung oil has been my go-to finish for 30 years. Primarily because it leaves the most beautiful rich finish. However, depending on temperature and humidity it can take several days to dry and up to 30 days to fully 'cure'.
From my research pure tung oil is 100% food safe. Avoid any oil with 'driers' including mineral oils which can include mercury. My nephew is extremely allergic to tree nuts (not peanuts) and if fine with tung oil boards.
Note a very few oils, like tung, cure through pure oxidation (combining with atmospheric oxygen to the end of their molecule) to permanently harden. Some vegetable oils, like sunflower oil, go rancid over time and should be definitely avoided. Some very good articles online.
Thank you very much, Cayman. Your extensive experience with tung oil is very helpful!
It has been very rainy and humid here, so I guess I will need to be patient for this first coat to dry.
Someone suggested that I use Sutherland Wells polymerized tung oil for the subsequent coats in order to move things along.
What are your thoughts on that?
They said it may not look as rich as pure tung oil. Is the difference very big?
Thank you SO much.
For non-food contact projects (ie. boxes) I thin the first coat of tung oil with mineral spirits 50-50. It dries much faster and penetrates better. Coats 2 and 3 at full strength. You have to be patient with tung oil as it can take two or three days to dry between coats.
I typically wipe on then wipe off any excess after 30 minutes. There was a recycled plastic ‘wool’ product I liked for the application because it slightly abraded the wood and didn’t leave metal fibres like steel wool on the surface but I can’t find it anywhere now.
The only tung oil I’ve used for years is Lee Valley branded. I’m not familiar with other brands. It’s readily available in Canada, not sure elsewhere.
I recently used Walrus Oil brand cutting board oil and wax for a bread board I made. I really like that. No smell and penetrated well. I got it at Lee Valley as well.
Thank you, Cayman. I appreciate all the details and product info.