Using used vegetable oils for preserving wood structures in the garden or farm

  Recently on letgo software a neighbor had 16 gallons of used rancid peanut oil to give away. She advertised it for a while and i collected it. Having already used corn oil successfully for wood preservation of a pine structured cage i built over the raised veggie bed. I thought the peanut oil would work well to help restore a variety of wooden structures around the  large garden. Its a thick oil and when applied, gets sucked right into the several year old wooden objects that have been bleached grey in the Californian sunshine. After a couple of days all the greasiness disappears and the wood goes darker and looks much younger. I am sure that this oil will make the wooden railings benches and raised veggie beds look and live for many years longer before cracking up into disuse. As an ex professional painter i realized that many wood preservers at Home Depot though effective are wildly over priced for basic yard based objects.And i urge others to explore used vegetable oils for  wooden garden items. I used it on bare wood fences, old benches, posts and wooden veggie beds as well as small wooden bridge over a stream. The color of the wood is also a nice rich dark brown instead of the old grey.

That's great! We use old rancid/oxidized vegetable oil as part of the process of burnishing unglazed pottery made from our native clay, and it works well for that, too. The oil burns off in the firing.

Good tips. I will give it a try. Thanks.
I used to send used and filtered cooking oil to a local shop. They burned all kinds of oil for heating in winter.

Where does one acquire used vegetable oil? Why would someone have a bunch of it sitting around?

Those who use deep fryers, including turkey fryers, at home inevitably have used vegetable oil. Restaurants produce lots of it. I used to collect it for the biodiesel co-op in Portland, Oregon from small restaurants and bars who were willing to put their used oil in empty five gallon totes-- the ones the fresh oil arrived in.

Thanks folks for the use suggestions! We still use a deep fryer.

We use old vegetable oil on all our outdoor wood.  It works better than paint or varnish.  The sun here dries  everything thing out in no time.  

Thank you for suggesting the use of vegetable oil.  Seems like a great nontoxic, or less toxic, substance to use on wood.  Are there any downsides?  Does the rancid smell dissipate eventually?

I know that rancid oil is bad for humans. Its probably the rancid compounds that is deterring/killing the decomposers.    

We use old oil on wood garden tool handles and on the steel as well. The oil we get is from the bulk dispensers at our food co-op - the dredges that they don't get drained from the containers. Free and not rancid at first, but we keep a gallon in the shed and just add to it so it's several years worth of accumulation. Much better than the old "recommendation" to dip tools in a bucket of sand wet down with used motor oil (with all of its toxic contaminants).

It will work great for coating various wood items around the yard, I used olive oil to coat the inside of my planter box when I built it but I could have used any waste vegetable type oil.  
I use it for a fire starter.   I think this winter will finish it but I am using my old peanut oil from the turkey fryer to soak small pieces of dry firewood (think 2/4 scrap) before using it to start a fire in my wood stove.  Using a small propane torch I can quickly heat a corner of the wood and get the oil burning, or using some paper or wax coated pine cones with the oil soaked wood the fire starts real quick and stays lit.  The oil is about 6" deep so I use 12" sticks so I have a dry end to grab.  It may drip a little, I just use another piece of wood to catch the drippings and then toss them both in the stove.
And no, it doesn't stink and it isn't yucky.

Great idea! Do critters ever end up chewing on the wood trying to get the oil? I'd imagine they'd avoid something rancid, but some of them don't seem too picky.

Crazy question -- the oil in fryers probably contains a lot of salt. Does this affect its usability for protecting wood?

Edit: Also, would it turn my fence into french fries for deer and porcupines?

I have access to a whole lot of used rapeseed deepfryer oil from my workplace. I also have many plans on my 1.5 ha land, including many uses for pallets and natural wood from home gardens / forestry waste.

Do you guys use such oil straight on the wood? Filter first? Cut with vinegar or lemon oil?

Heather Sharpe wrote:Great idea! Do critters ever end up chewing on the wood trying to get the oil? I'd imagine they'd avoid something rancid, but some of them don't seem too picky.

I don't rub/paint used vegetable/cooking on wood/handles because we have this small red ant that comes and covers such a treated object{fried chicken bones} with soil. They then encamp there. This is why my bucket of oil soaked tissue/rage/newspaper{all set aside for starting fires} is suspended out of their reach. I would hate to burn any ants still lingering. I don't know which oils are safe but palm oil cooking oil{plentiful here} does not seem to WARNING spontaneously combust as Linseed oil WILL. I read that coconut oil will also spontaneously combust. So I rub my wooden handles with used engine oil. I was neglecting all the engine oil soaked newspaper until I came across the Linseed oil danger. I think that is safe to leave about as I see a lot of greasy rags at the car workshops.

In my amateur woodworking adventures I've mostly been steered towards using drying oils for wood finishes. The advice has always been to avoid oils that go rancid and don't polymerize. I guess if you're using them outdoors and not for skin contact or food contact it doesn't really matter though does it?

My plan for otherwise useless vegetable oils was to one day use as a lamp oil. I've heard most will burn fine, even very old rancid ones.

Just had to look this up used vegetable oil on part of my chicken cage.. Thanks for you help 🙂

Decades in to wood working, and hundreds of gallons of everything from tung oil and tung oil finishes (e.g., boiled linseed oil by another advertising name) to polyurethane or resin behind me, I, too avoid any oil that can go rancid. This includes untreated flax seed (linseed) oil, olive oil and so on.

I've had to walk away from stupid customers who thought themselves experts and insisted I treat wood with olive oil. You could smell their cutting boards and knew they were soaked with rancid oil.

Though boiled linseed oil is treated (air is ran through it, to partially polymerize it, making the process look like the oil is being boiled, before agents are added to speed hardening), it, still, is not a good choice for exterior wood protection. In fact, certain fungus and bacterial love it.

Tung oil, the real stuff and not the bogus "tung oil finish" sold downtown does not fare much better than linseed oil, until it has resins and such added, at which time is becomes a common, polymer finish.

I've treated a lot of fences and things with non-hardening oils, including scary used motor oil. The oil, when thinned, penetrates wood and replaces lost moisture, reducing or stopping cracking and splitting, depending on how aggressive one is in applying the penetrating oil finish.

If cedar shingles were treated with non-hardening oils, rather than left to shrink, crack and split, their life span would be far greater than untreated shingles and shakes.  In fact, if they were treated to a point of near saturation, they could be walked on in the dead of a hot summer without breaking, because they remained flexible.

Once a fence or other exterior surface had reached a point it seemed the oil applications tended to more rest on the surface than soak in, then seal coating could be added, to seal the oil in.  This is not an overnight process though. It is the result of several applications over the course of a few years.

The pay off of the non-hardening oils is, when wood is full of oil, it will not take on water, which can freeze and add to damage of the wood.  Too, the oil does not evaporate (thought the thinner will), so the wood does not shrink, crack and split.

L. Johnson wrote:In my amateur woodworking adventures I've mostly been steered towards using drying oils for wood finishes. The advice has always been to avoid oils that go rancid and don't polymerize. I guess if you're using them outdoors and not for skin contact or food contact it doesn't really matter though does it?

My plan for otherwise useless vegetable oils was to one day use as a lamp oil. I've heard most will burn fine, even very old rancid ones.

The primary danger of oil soaked rags is with hardening oils, like tung oil and linseed and other such oils.  The reason they are a problem is, they react with oxygen in the course of hardening. The reaction generates heat.

For that reason, I spread my rags out so they get a lot of air during the hardening process. It's kind of cool. Take an old diaper, for example, saturate it with boiled linseed oil, shape it and let it harden (again, with lots of air around it). You end up with a pretty cool, hard rag you can paint (you, not me, because I have the talent of a kindergartner).

L. Johnson wrote:In my amateur woodworking adventures I've mostly been steered towards using drying oils for wood finishes. The advice has always been to avoid oils that go rancid and don't polymerize. I guess if you're using them outdoors and not for skin contact or food contact it doesn't really matter though does it?

My plan for otherwise useless vegetable oils was to one day use as a lamp oil. I've heard most will burn fine, even very old rancid ones.

Is there an increased fire risk for outdoor structures treated with used oil, whether vegetable or motor oil? Asking for those of us who live in areas of summer drought and wildfires.

When I tried to explain to my friend, the owner of five cedar mills (Pacific Northwet) he needed to treat the cedar shingles and shakes  on his house to protect them, the potential flammability of the oil was his first concern. I reminded him he doused the cedar in the burner for the mill waste with five gallons of kerosene, then spent the next ten or fifteen minutes trying to ignite it.  I also reminded him a single match to the thin end of a dry shingle would light it on fire.

Try a little experiment with some oil which has not been thinned, like mineral oil, then try some dry wood at a thin point and see what you think.  Toss into that mix a test of a oil soaked piece of cedar or other wood.  The point is not to see if it would burn, but to see how quickly it takes off.

Of course, once the oil soaked wood got going in a fire, you'd have a very genuine fire. However, I don't think a fire on a dry, cedar roof wood be a good thing either.

IF a person wanted to experiment, one could mix in borax at different ratios and try the above experiment.  Borax is used to knock down fires, and to deter rot and termites, but washes away in the rain. It might be the oil could be played with to hold the borax, if you wanted to retard the fire potential.  

I, definitely, would oil the dickens out of my cedar roof, aiming for saturation.  The cedar shakes would last a hundred years if they didn't rot, split and crack, which oil stops.  That said, I'd make sure my chimney and stove pipes had good fire screens.


As to the issue of wild fires, if I did have a cedar roof, embers landing on it would strike fear in me.  Certainly if the cedar was dry. I would be less concerned about the vertical walls.  As we know, the best way to avoid losing a house or outbuilding to a wildfire is:

-  no firewood stored near the house, unless it's shielded from flying, burning debris;
- no flammable bushes (especially avoid high turpine type shrubs and things, like arborvitaes);
- give yourself as much distance between flammables as possible, such as with gravel and green lawn (the more "hundreds of feet) you can get, the better;
- avoid wood and asphalt roofs and stay with tile and metal;
- . . . .

Andrea Locke wrote:Is there an increased fire risk for outdoor structures treated with used oil, whether vegetable or motor oil? Asking for those of us who live in areas of summer drought and wildfires.

Does the oil need to be used??  I gave a couple of bottles of oil that Im not using???

Awesome hv wondered about using on 100 year old fence posts
  r4bookoo@gmail.com
Thanks

When I was a chicken rancher there was a lice issue in one of the poultry houses. I finally coated the entire interior of the poultry house with rancid veggie oil. Seems the lice live in the cracks of the wood and that's why I couldn't get rid of the little suckers. After coating the walls, floors and roosts the lice issue abated. There are many uses for oil...rather than chemicals! I used a brush to apply the oil since I didn't think a pump-up sprayer would be good for flow.

Kelly Craig,

What type of non-hardening oils would you recommend for outdoor use? Peanut, Canola, ...?

Thank you!

~Michael

Kelly Craig wrote:
...
I've treated a lot of fences and things with non-hardening oils, including scary used motor oil. The oil, when thinned, penetrates wood and replaces lost moisture, reducing or stopping cracking and splitting, depending on how aggressive one is in applying the penetrating oil finish.
...

That makes sense. Orchardists use mineral oil treated so it'll stay in suspension in water. Sprayed on the trees, the oil suffocates coddling moth larva.

I've put a LOT of oil on wood with a pump up sprayer, but it had to be thinned or it was all over before it started.

cynda williams wrote:When I was a chicken rancher there was a lice issue in one of the poultry houses. I finally coated the entire interior of the poultry house with rancid veggie oil. Seems the lice live in the cracks of the wood and that's why I couldn't get rid of the little suckers. After coating the walls, floors and roosts the lice issue abated. There are many uses for oil...rather than chemicals! I used a brush to apply the oil since I didn't think a pump-up sprayer would be good for flow.

I've only used motor oil and mineral oil.  

As to the other oils, my buddy's tractor smells like a popcorn popper with a round of popcorn ready to go. He picks up all the garbage oils (horrible even before they go rancid) like Canola oil and all the vegetable oils, then processes them for his farm equipment.

The one big caution about olive, vegetable, Canola and linseed oil (even "boiled") is, in certain climates or conditions they invite growth of mildew. Some things think it's tasty. Hey, I guess even septic tank anaerobic critters have to eat.

Even olive oil gets tacky after going rancid. I've seen too many otherwise beautiful cutting boards in dire need of major cleaning because someone thought they were being more health conscious by using it instead of mineral oil.

Michael McCord wrote:Kelly Craig,

What type of non-hardening oils would you recommend for outdoor use? Peanut, Canola, ...?

Thank you!

~Michael

Kelly Craig wrote:
...
I've treated a lot of fences and things with non-hardening oils, including scary used motor oil. The oil, when thinned, penetrates wood and replaces lost moisture, reducing or stopping cracking and splitting, depending on how aggressive one is in applying the penetrating oil finish.
...

Good question - new or used doesn't matter. It'll do the same thing. Some might be worried about the metals contaminating the oil. That shouldn't be a big problem if you aren't licking the wood     and are using it on, for example, raw wood walls of a chicken house, or you're soaking the bottom of posts in it before burying them for a fence. . . .

Susan Kolstoe wrote:Does the oil need to be used??  I gave a couple of bottles of oil that Im not using???

Susan Kolstoe wrote:Does the oil need to be used??  I gave a couple of bottles of oil that Im not using???

I would also like an answer to this question? I could grab a couple of bottles right now that I'm about to throw away, not rancid, but I'm cleaning out a house for someone and it's going to be thrown out or I could use it for maybe getting rid of a lot of unwanted creatures???

I have two main issues at my place. May 15-July 15 is wood tick season, and they love my place. The first year I had to deal with them I spent a full hour one day killing them left and right on the front door, door casing, of my house. Would it work against ticks?

The other issue is with mice. Would it work against mice?

I have used it for chain saw bar oil.

I have a bit of beef fat that has turned. Has anyone used it on outdoor wood? I’m thinking about my chicken coups. And I’m wondering if using it would deter or attract animals such as raccoons? Just wondering if anyone has used fat on wood. Cheers