mitigating future rancidity
September 9, 2018 7:38 AM Subscribe
I just soaked a pile of cedar in canola oil. I was oiling it! And then realized that it's going to go rancid. How do I fix this?!
Clearly I don't have piles of woodworking experience. But we're building out kitchen shelving! It's going well other than this.
Clearly I don't have piles of woodworking experience. But we're building out kitchen shelving! It's going well other than this.
Response by poster: We oiled everything, including the end grain. And it's all cut to size.
posted by aniola at 8:18 AM on September 9, 2018
posted by aniola at 8:18 AM on September 9, 2018
More details would be good.
In general, wipe off as much oil as you can. Keep using fresh rags until they come away mostly dry. Some canola oil will have soaked in and gradually polymerize. That's what an oil finish is.
Canola oil is not the oil you'd typically use, though.
But on the other hand, as long as you remove as much oil from the surface as possible, then in a couple days you can come back with a real oil finish, ideally with a drying additive (which makes the oil polymerize much faster than naturally), and this will seal in any possible canola rancid odour issues.
posted by seanmpuckett at 8:20 AM on September 9, 2018 [7 favorites]
In general, wipe off as much oil as you can. Keep using fresh rags until they come away mostly dry. Some canola oil will have soaked in and gradually polymerize. That's what an oil finish is.
Canola oil is not the oil you'd typically use, though.
But on the other hand, as long as you remove as much oil from the surface as possible, then in a couple days you can come back with a real oil finish, ideally with a drying additive (which makes the oil polymerize much faster than naturally), and this will seal in any possible canola rancid odour issues.
posted by seanmpuckett at 8:20 AM on September 9, 2018 [7 favorites]
I personally like Minwax's Tung Oil finish. A nice golden tone, goes on and dries to the touch in minutes, buff it, recoat after a day, sets up very firmly in a few days. Good stuff.
posted by seanmpuckett at 8:23 AM on September 9, 2018 [1 favorite]
posted by seanmpuckett at 8:23 AM on September 9, 2018 [1 favorite]
Response by poster: More details would be good.
Not sure what to add. It's low quality cedar with big pores and soaked in canola oil, but it's what we have.
posted by aniola at 8:24 AM on September 9, 2018
Not sure what to add. It's low quality cedar with big pores and soaked in canola oil, but it's what we have.
posted by aniola at 8:24 AM on September 9, 2018
OK, yeah, I vote just sop up what you can, use as much paper towel as you need until it comes away dry (and dispose of it sealed in several air-tight bags), hand-sand down the whiskers the oil raised, then come back after a day with the Tung Oil. That's what I'd do if I essentially spilled a bunch of cooking oil on a furniture project.
posted by seanmpuckett at 8:27 AM on September 9, 2018 [1 favorite]
posted by seanmpuckett at 8:27 AM on September 9, 2018 [1 favorite]
Rancidity is what happens when a vegetable oil partially oxidises. It makes the oil unfit to eat, but it doesn't mess up its ability to preserve timber. The problem with canola oil for timber preservation is not rancidity per se, but the fact that rancid canola oil is kind of sticky rather than kind of hard.
So I'd spend the next few days wiping canola off the cedar with old rags, until the surface didn't feel slick any more. A good deal of it will have soaked in, and that's OK. Next, I'd rub it over once a day for the next few days with a rag soaked in a drying oil like linseed or tung. This will mix with the residual canola oil to some extent, but what's nearest the surface will still polymerize and form a harder and more durable coating than you'd ever get from a non-drying oil like canola.
Linseed oil is the ingredient that makes oil paints set to a tough, durable finish. If you use raw linseed on your shelving, it will take maybe a couple of weeks to harden properly. "Boiled" linseed oil contains additives that make it harden in a matter of days; the same kind of additives are also in oil paints and commercial oil-based furniture finishes based on tung oil as well. They're poisonous if you eat them but no problem on the surface of furniture.
If you're using an oil-soaked rag to apply a drying oil, keep it well wrapped in clingfilm while you're not using it, then use it to fire up your barbecue charcoal after you're done or hang it up somewhere outdoors, spread right out flat, until it's dried stiff. The oxidation reaction that hardens those oils is exothermic, and bunched unattended linseed-oiled rags with access to air do sometimes build up enough internal heat to burst spontaneously into flame.
posted by flabdablet at 8:27 AM on September 9, 2018 [14 favorites]
So I'd spend the next few days wiping canola off the cedar with old rags, until the surface didn't feel slick any more. A good deal of it will have soaked in, and that's OK. Next, I'd rub it over once a day for the next few days with a rag soaked in a drying oil like linseed or tung. This will mix with the residual canola oil to some extent, but what's nearest the surface will still polymerize and form a harder and more durable coating than you'd ever get from a non-drying oil like canola.
Linseed oil is the ingredient that makes oil paints set to a tough, durable finish. If you use raw linseed on your shelving, it will take maybe a couple of weeks to harden properly. "Boiled" linseed oil contains additives that make it harden in a matter of days; the same kind of additives are also in oil paints and commercial oil-based furniture finishes based on tung oil as well. They're poisonous if you eat them but no problem on the surface of furniture.
If you're using an oil-soaked rag to apply a drying oil, keep it well wrapped in clingfilm while you're not using it, then use it to fire up your barbecue charcoal after you're done or hang it up somewhere outdoors, spread right out flat, until it's dried stiff. The oxidation reaction that hardens those oils is exothermic, and bunched unattended linseed-oiled rags with access to air do sometimes build up enough internal heat to burst spontaneously into flame.
posted by flabdablet at 8:27 AM on September 9, 2018 [14 favorites]
Tung oil, by the way, is the main component in the Danish oil Leon recommends. Both linseed and tung oils make lovely finishes on wood. Linseed will darken the surface much more than tung will. It's also astonishingly cheap compared to every other oil-based alternative.
posted by flabdablet at 8:35 AM on September 9, 2018 [1 favorite]
posted by flabdablet at 8:35 AM on September 9, 2018 [1 favorite]
Cedar is also quite an oily wood even without adding your own. I've seen some lovely, durable, lustrous cedar furniture made with no surface treatment at all beyond fine sanding. But now that you've added a non-drying oil to yours, I think you'll find that a drying oil to finish it will work out best.
posted by flabdablet at 8:38 AM on September 9, 2018 [1 favorite]
posted by flabdablet at 8:38 AM on September 9, 2018 [1 favorite]
You might be able to break up the oil with some diluted ammonia but you HAVE to test it on a piece of scrap first and keep the windows all open. Try a 1 to 4 ammonia to water mix. Make sure you give the wood a week at least to dry out afterwards before applying anything else.
...but I would only really worry about it going rancid if you were using it inside a cabinet.
posted by bonobothegreat at 8:40 AM on September 9, 2018
...but I would only really worry about it going rancid if you were using it inside a cabinet.
posted by bonobothegreat at 8:40 AM on September 9, 2018
Another consideration: ultraviolet light will accelerate all the rancidification reactions. So if these shelves are going into an enclosed space where the buildup of rancid smells might be a concern, you might want to leave your cedar outside in the sun for a few days after blotting up as much oil as you can, to encourage the remaining oil go as rancid as it's going to get as quickly as possible and vent all its stinky reaction products outdoors. Bring it back inside once it starts to smell more like cedar than old Parmesan.
posted by flabdablet at 8:49 AM on September 9, 2018 [4 favorites]
posted by flabdablet at 8:49 AM on September 9, 2018 [4 favorites]
Oils meant for use as a wood finish are formulated to dry in a reasonable time. For example, linseed oil is boiled. Canola oil might take quite a while to dry properly. I would clean it several times with turpentine, any turpentine remaining in the oil will help in dry and harden.
posted by theora55 at 9:24 AM on September 9, 2018 [4 favorites]
posted by theora55 at 9:24 AM on September 9, 2018 [4 favorites]
There could be a danger of warping from this, but I would be tempted to haul the boards to a self-service car wash to take advantage of the high pressure wands to clean off the oil. I'd use one soap cycle and two rinse cycles.
And I would not use tung oil to finish the boards, though I might try to seal the ends of the boards by rubbing them with unscented candle wax and melting it in with a hair dryer.
posted by jamjam at 9:55 AM on September 9, 2018
And I would not use tung oil to finish the boards, though I might try to seal the ends of the boards by rubbing them with unscented candle wax and melting it in with a hair dryer.
posted by jamjam at 9:55 AM on September 9, 2018
No no please, don't take them to a carwash, they will warp like crazy. Same with any form of dryer or other heat treatment.
I have solid oak table-tops and I treat them with cooking oil all the time. I mean, now and again (read: less than once a year, so rarely it might as well be never) I sand them down to remove damages and then I treat them with what we call teak oil, which I suspect is the same as Danish Oil. Linseed is better, but teak oil is easier to work with.
However, every now and then, when I'm standing with a bottle of vegetable oil of any sort, I pour a couple of spoonfuls over the table and rub it in with paper towel. It's good for my table-top, and it keeps off damages from water spills around the sink and stuff like a leaking container entirely. I don't think it can harm your boards. Since I wipe the top several times a day, the effect wears off rather rapidly. I think like most people above that you can just wipe the boards as dry as possible, and then treat them with a more appropriate and longer lasting oil.
posted by mumimor at 10:39 AM on September 9, 2018 [3 favorites]
I have solid oak table-tops and I treat them with cooking oil all the time. I mean, now and again (read: less than once a year, so rarely it might as well be never) I sand them down to remove damages and then I treat them with what we call teak oil, which I suspect is the same as Danish Oil. Linseed is better, but teak oil is easier to work with.
However, every now and then, when I'm standing with a bottle of vegetable oil of any sort, I pour a couple of spoonfuls over the table and rub it in with paper towel. It's good for my table-top, and it keeps off damages from water spills around the sink and stuff like a leaking container entirely. I don't think it can harm your boards. Since I wipe the top several times a day, the effect wears off rather rapidly. I think like most people above that you can just wipe the boards as dry as possible, and then treat them with a more appropriate and longer lasting oil.
posted by mumimor at 10:39 AM on September 9, 2018 [3 favorites]
Yeah good grief do not wash them with water, at a car wash or otherwise. Wipe the boards dry, then use an oil that contains drying agents (like BLO) to help the remaining canola set. Try it on just one board first to make sure it doesn't e.g. completely discolor everything.
As long as you use proper ventilation and handling techniques (gloves! don't get it all over you! don't eat off it!) tung oil is as safe as linseed oil, and pure tung oil is generally considered food safe once it sets. Although FYI most of the "tung oil" on the market, including both the Danish Oil and Minwax tung oil finish mentioned above, is actually a blend of tung and other oils. Real tung oil doesn't contain drying agents, takes quite a long while to set properly, and is much more expensive.
posted by aspersioncast at 12:49 PM on September 9, 2018 [2 favorites]
As long as you use proper ventilation and handling techniques (gloves! don't get it all over you! don't eat off it!) tung oil is as safe as linseed oil, and pure tung oil is generally considered food safe once it sets. Although FYI most of the "tung oil" on the market, including both the Danish Oil and Minwax tung oil finish mentioned above, is actually a blend of tung and other oils. Real tung oil doesn't contain drying agents, takes quite a long while to set properly, and is much more expensive.
posted by aspersioncast at 12:49 PM on September 9, 2018 [2 favorites]
I would be tempted to bury the pieces in kitty litter for a day or two. When I’ve spilled oil on concrete, putting kitty litter on it works a charm. I Haven’t tried it with wood, though.
posted by shalom at 1:15 PM on September 9, 2018
posted by shalom at 1:15 PM on September 9, 2018
I don't think it will be a problem. Long ago, I oiled a chair with olive oil. No rancidity ensued.
posted by pinochiette at 4:48 PM on September 9, 2018 [1 favorite]
posted by pinochiette at 4:48 PM on September 9, 2018 [1 favorite]
My pine chopping board has been treated with linseed, olive, canola, sunflower or whatever else has wanted using up when it started looking a little in need of love, and it doesn't smell bad either. Your shelves are probably not going to get hot water run over them on a daily basis, and you will probably care more about their ongoing flatness than I do about that of my chopping board, but even so I agree with pinochiette that the rancidity issue is probably not serious enough to worry about.
posted by flabdablet at 2:54 AM on September 10, 2018 [2 favorites]
posted by flabdablet at 2:54 AM on September 10, 2018 [2 favorites]
What about mineral oil?
posted by wenestvedt at 3:09 AM on September 10, 2018
posted by wenestvedt at 3:09 AM on September 10, 2018
Mineral oil doesn't contain the unsaturated bonds responsible for both rancidity and spontaneous polymerization. When it's applied to wood it just soaks in and then stays there pretty much as-is until it slowly, slowly evaporates; any preservation effect it has on the wood is limited to purely displacing and/or repelling water. It also makes it harder for other finishes to adhere well, and will soften polishing waxes.
I don't like applying it to chopping boards or other wooden utensils because even food-grade mineral oil is not in any way a food.
posted by flabdablet at 5:30 AM on September 10, 2018
I don't like applying it to chopping boards or other wooden utensils because even food-grade mineral oil is not in any way a food.
posted by flabdablet at 5:30 AM on September 10, 2018
This thread is closed to new comments.
You could try sealing it but I doubt that's going to work (because you're putting sealant over a non-drying oil).
Which leaves you taking the surface off mechanically (plane, sander, etc). Hopefully you didn't oil the end-grain, because that will soak up the oil like blotting paper and you could easily lose the best part of an inch there.
In future, Danish oil is nice....
posted by Leon at 8:16 AM on September 9, 2018