# Tung Oil



## brad (Sep 17, 2007)

I was reading my buddy's blog (Sarge), and some of your comments, as a result Sarge and I started talking about his favorite finish "Tung Oil" which brought up the questions…what is tung oil,(all products called tung oil aren't really tung oil? That lead to how do you use it? when do you use it? why use it/why not? We thought this would ne a good place to see what everyones experience has been and comments about anything "tung oil " related


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## SPalm (Oct 9, 2007)

I love it, but it does need to be 'rubbed' in to really work.

It is from the nut of the Tung tree. The story I have heard is that the British were blow away by the Chinese Junks and their water tightness and beauty. At that time the Tung tree was only in China and the British used pine tar to waterproof their boats (yuck). Anyway, Tung oil is unique in that it is one of the few oils that polymerizes or actually hardens. It becomes water proof. The concept of Tung Oil Finishes (Watco, etc.) are blends of Tung and other oils to produce an easier to apply oil with less cost.

Then again, I could be wrong.
Steve


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## SteveRussell (Jul 23, 2007)

Hello Brad,

Here is a bit of detailed information to help you understand Tung Oil. Tung oil is obtained from the seed kernels of the Tung tree, Aleuritis fordii (Chinese tung oil) or Aleuritis cordata, syn. vernica and verrucosa (Japanese tung oil). The principal source of raw tung oil is China and South America. The nuts of Aleuritis montana, Aleuritis trisperma (kekunaoil) and A. moluccana or A. triloba (lumbang oil) also produce oils with properties that are similar to Chinese tung oil.

In 1298, Marco Polo reported that tung oil together with lime had been used for impregnating and sealing wooden ships. As early as 1894, tung oil was being imported into Europe and the United States as a substitute for linseed oil. Tung oil is produced by mechanical pressing, or by solvent extraction. The resulting oil is then filtered to remove any impurities.

Drying oils, including linseed and tung, can be defined as liquid vegetable oils that, when applied in thin layers to a non-absorbent substrate, will dry in the air to form a solid film. This drying is a result of polymerization by the action of atmospheric oxygen, i.e. autoxidation.

The resultant films are typically hard, non-melting and are usually insoluble in organic solvents. (This varies with the particular drying oil) Semi-drying oils, like soybean oil and some nut oils, form tacky, somewhat sticky films when dried. Non-drying oils like mineral oil undergo no marked increase in viscosity upon exposure to air.

Drying oils are typically subdivided into three main groups for classification purposes, non-conjugated, conjugated and other oils. Non-conjugated oils, such as linseed, soybean, sunflower and safflower oil, are fatty oils that contain polyunsaturated fatty acids, whose double bonds are separated by at least two single bonds (i.e. isolated double bonds make up the non-conjugated oils).

Conjugated oils on the other hand, such as tung, oiticica, dehydrated castor oil and isomerised non-conjugated oils are polyunsaturated fatty acids whose double bonds are partly or fully conjugated (i.e. alternate single and double bonds in the carbon chain are the fatty acids). Other oils include those with multifunctional fatty acids, which acquire their drying characteristics by chemical conversion, such as raw castor oil and tall oil. A simple way to classify fatty oils is by their iodine value. Drying oils have iodine values above 170, whereas semi-drying oils range between 110 and 170.

Conjugated oils like tung oil are considerably more reactive than non-conjugated oils. Conjugated double bonds favor polymerization and oxidation and dry more rapidly than non-conjugated oils, offering excellent surface-dry, through-dry and hardness. The resultant film offers a high resistance to yellowing and increased resistance to water and alkalis.

The principal drying component in tung oil is eleostearic acid, a conjugated octadecatrienoic acid. The oleic acid contained in the fatty oils and unsaturated fatty acids plays a small part in the drying process as well. The saturated fatty acids present, however, act only as plasticizers.

The drying of films typically progresses in three overlapping steps:

Induction - Through a process known as autocatalysis, the oxygen uptake, which is slow at first, steadily increases. Factors such as temperature, light and heavy metals/inhibitors in the oil affect the overall uptake rate.

Initiation - As the film continues to take up oxygen, its mass increases. The double bonds in the film begin to rearrange and polar groups such as hydroxyl and hydroperoxy develop in the film. This leads to the association of molecules, through forces such as hydrogen bonding.

Cross-Linking - As the number of double bonds in the film begins to diminish, larger molecules form, and volatile and non-volatile carbonyl compounds are generated. The exact chemical reactions, as well as the structure of the film-forming polymers, are not completely understood. The initial autoxidation step in non-conjugated oils is dehydrogenation of the unsaturated fatty acid by molecular oxygen, which forms a radical. This starts a catalytic radical chain reaction that increases incrementally with time, leading to the formation of a hydroperoxide.

At low levels, the hydroperoxides produced during autoxidation decompose to form free alkoxy and hydroxyl radicals. Higher levels of hydroperoxides form free radicals through biomolecular disproportionation. The resultant free radicals react in various ways to accelerate the autoxidation process.

The drying of tung oil varies considerably from linseed oil. Tung oil typically absorbs approximately 12% oxygen (linseed oil absorbs approx. 16%) and quickly forms a skin on the surface. Since less oxygen is absorbed, the viscosity of the oil increases at a faster rate. Unlike the hydroperoxide formation during autoxidation in linseed oil, tung oil forms cyclic peroxides. The methyl eleostearate that is formed has a higher molecular mass than linoleic acid esters.

The direct attack on the double bonds by oxygen forms cyclic peroxides. The resultant reaction of the peroxides with allylic methylene groups, leads to the formation of radicals. This creates a radical chain reaction that forms polymers. The molecular mass created during tung oil polymerization is less than that achieved through linseed oil polymerization. To speed up the film formation and curing process, manufacturers add "driers" to the oils.

Both non-conjugated and conjugated drying oils like linseed and tung can be polymerized by heating under an inert atmosphere. These polymerized oils are then referred to as "Bodied Oils." To achieve the higher viscosities of bodied oils, non-conjugated oils are heated up to 320° Centigrade and conjugated oils are heated up to 240° Centigrade.

This increase in viscosity, or "body," is caused from thermal decomposition of naturally occurring hydroperoxides. This decomposition yields free radicals that contribute to a limited amount of cross-linking.

The heating of tung oil must be carefully monitored, or the polymerization will lead to gelation of the oil. The viscosity can also be increased by passing air through the oil (known as Blown Oils) at high temperatures up to 150° Centigrade. Reactions similar to those observed in cross-linking cause oligomerization of the oil.

Polymerized tung and linseed oils dry faster, harder and are more durable than raw oils. In addition, polymerized oils produce a smooth glossy finish, whereas raw oils produce a matte sheen. This matte sheen is a result of the natural expansion that takes place during polymerization. This expansion creates a very finely textured surface that appears to the naked eye as a matte finish.

Some highly specialized polymerized tung oils are processed at extremely high pressures and temperatures. These are called Thermalized Tung oils and are used in the manufacture of nitro-cellulose lacquers. This process improves the drying, hardness and luster of the oil.

I hope this helps you to understand Tung oil a wee bit. Take care and all the best to you and yours!

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## Karson (May 9, 2006)

We just asked for the time, not how to build a watch. LOL

Thanks for the explanation.

Is this a cut and paste or did it all come from your flying fingers.


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## Dadoo (Jun 23, 2007)

Zzzzzzz-zzzzzzzz* Wha?

Just kiddin! LOL!


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## SPalm (Oct 9, 2007)

Cool, we got ourselves an expert.

Steve, do you have any recomendations for a cutting board finish?

Take care,
The other Steve


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## Hutch (Sep 24, 2007)

OK, but are some finishes that are labeled Tung Oil really an oil/varnish blend, not just a combo of different oils?


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## CharlesNeil (Oct 21, 2007)

cutting board finish,yep, the total concept of "food safe " is a hype pure and simple, in years past the metal driers in finishes contained lead, definately unsafe, today the driers do NOT contain lead, fact is there is no known clear finish that is harmful ,once it has cured and driers cure it,with exception to shellac ,none of them will ever return to a liquid state, thus not be a digestable concern, shellac is actually used for "time released medicine's", as it dissolves slowly and actually dissolves in the intestines thus the time release.General finish has a Salad bowl finish that actually works, it is actually blo with some good resins and driers to actually protect and seal wood,the typical "food safe " stuff is mineral oil, which does nothing to protect the wood ,but remains wet so it makes it look good, its just that it doesnt go rancid,so its safe ,it is sold at the drug store as a laxitive, in a class one time i took a big swig to demonstrate my point, wouldnt suggest that, it works for its intended purpose but for wood it isnt a good choice, i was absent from class numerous times for the balance of the day!


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## SteveRussell (Jul 23, 2007)

Hello Karson,

Please accept my apologies for the long post. Chemistry is a hobby of mine, so I tend to get excited about it, although it's a sure cure for insomnia for most folks. The post is excerpted from an article I wrote for the British "Woodturning" Magazine a few years ago. Since I'm a lousy typist (my wife says I type with my elbows… She types over 140 WPM :-o), I try not to reinvent the wheel if possible.

I wrote articles for Woodturning magazine for a few years. They were the ONLY magazine that would let me publish in-depth technical articles. Most magazines want you to write for an 8th grade education level, I think woodturners and woodworkers are smarter than that… So I rarely write articles for magazines anymore. Since I have a website now, I tend to publish my articles online now.

Dadoo… Apologies for putting you to sleep.

Steve - I like your name!  Usually, Mineral oil is recommended for cutting boards. MO will not cure as it is a non-drying oil and will continually leach out with every washing, requiring periodic reapplication. It will also leave a mess on your countertops if you apply too much… Ick! The problem with cutting boards is that you cut on them, so any type of film finish is pretty much out of the question.

If you cut raw meat on your cutting board, it's a good idea to perform a salt rub every so often to insure a sanitary surface. Wet the board slightly and pour salt all over it. Let it sit for an hour or so and wash it off. Many folks have switched to plastic boards for meat, but some purists prefer still prefer wood. I have Walnut oil on my cutting boards, which I reapply periodically. I just don't care for Mineral oil…

Hutch - It depends on the specific finish. Some finishes labeled as "Tung Oil Finish" do not contain a single drop of Tung oil. Some have a small amount of TO, blended with other oils. Some are "Pure" 100% Tung oil. You have to be careful though because manufacturers and re-labelers seem to be able to call their finish almost anything these days, without repercussion. It's false advertising, but unfortunately a common practice with some finishing companies.

You can request an MSDS sheet and see if Tung oil is in a particular finish, but even that is not a 100% guarantee it seems. If you've got a gawalop of cash, you can order a GCMS test, with supplemental flash point testing. This is pretty expensive though… You would know for sure though…  Take care and all the best to you and yours! I'll retreat to my laboratory now and refrain from posting long responses… 

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## SST (Nov 30, 2006)

Now if only I could find a Groove tree, extract some groove oil, and mix it with the aforementioned oil, I'd have the perfect finish for my floors…Tung & Groove oil.
Oow…I really hate it when I do that…but it was just a little slip of the tung or maybe…a tung-in-cheek remark… -SST
Wait, I've got another…it's…it's…nuts, it's right on the tip of my tung…
Ok, I'm really done, now…I'm all tung-tied.


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## SPalm (Oct 9, 2007)

TO sst, your humor is BLO me.

So good, I have been using walnut oil on my cutting board counter and it is OK. (you can buy it at the supermarket)

Charles, thanks for the visual. 
I will try out that Salad Bowl Finish.

Steve


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## SteveRussell (Jul 23, 2007)

Hello Charles,

I use General Salad Bowl Finish all the time… It contains the following:

C.A.S.#

8052-41-3 Mineral spirits 20-40% 
64742-47-8 Mineral spirits 10-20% 
64742-48-9 Mineral spirits 5-10% 
111-84-2 Nonane 5-10% 
Proprietary Oil modified urethane resin 10-35% 
Proprietary Resin 0-25% 
95-63-6 1,2,4-Trimethylbenzene 0-1%

You're right that modern driers do not contain lead anymore… (Driers are oil soluble metal salts of organic acids. When these driers are dissolved in aliphatic or aromatic hydrocarbons, they are known as siccatives. When driers are added to drying oils, they are known as Boiled Oils).

Traditionally, driers contained combinations of oil-soluble metal salts like Cobalt and/or Manganese with Zirconium, Lead or Calcium salts of 2-ethylhexanoic acid or naphtenic acids. Cobalt and Manganese salts act as surface driers and aid in the drying of the film on the surface, where oxygen concentrations are the highest.

Lead and Zirconium salts catalyze throughout the film and are known as through driers. To avoid the use of Lead, which is highly toxic, modern siccatives employ blends of Cobalt and Zirconium. This combination reduces surface drying speed, promoting even drying throughout the substrate. Calcium salts are sometimes used as well, mainly to reduce the amounts of other driers that may be needed. Various other compounds may also be present in some siccatives including Beryllium, Cadmium and Nickel. Take care and all the best to you and yours!

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## Betsy (Sep 25, 2007)

dag gum it, I've always thought that mineral oil was the end all on the topic of cutting boards. So now, let me recap.

Mineral oil = ok - but leeches and needs reapplied. Will go rancid and if swallowed in great gallops in class - makes you go and go and go and go.

Walnut oil = ok - tastes better than mineral oil. Probably not a good idea to drink straight from the bottle, but probably could.

Someone needs to rap SST on the knuckles (I digress).

Pretty much any finish is ok for a cutting board except shellac because it can be reliquified (is that a word?).

General Salad Bowl Finish is a favorite and probably a no brainer to put this baby to bed.

Steve - I've never understood chemistry. Buuuuuuuuuuuuuuuuuuutttttttttttt - oh geez sorry - I got a little sleepy there. Whew - ok. so back to chemistry. Really a good article. My brother is sicentist of the USDA and honestly, I can't get by the titles of his papers. He once used the words "potatos" and "bug" together. I felt like I finally understood him. First time in years.

Now back to this finish thing-- with the fact that all these finishes - dry - except that shellac-- does this also mean that walnut oil would *probably* not cause a problem with those who suffer nut allergies?

Ok - enough questions. Need some answers before SST comes up with anymore tung and cheeck groaners.


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## SST (Nov 30, 2006)

Sorry, Betsy…I'm oil finished. -SST


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## SteveRussell (Jul 23, 2007)

Hello Betsy,

Mineral oil will not go rancid over time… It will not dry (or cure) either. Mineral oil is a non-drying oil and as such, it will continue to leech out of the wood when it's washed. If you apply too much, it weeps it's way through the board/bowl etc, leaving a nice greasy ring on your counter, or on your Mums Irish lace tablecloth (don't ask). It is considered food safe and a version of it is sold in drug stores for intestinal disorders.

Walnut oil does indeed taste better than Mineral oil… I cook with Walnut oil (from the grocery store) all the time. In fact, it's about the only oil I use in baked goods anymore. I prefer Walnut oil for Treenware (utility wooden objects like bowls, platters, cutting boards etc) because it's made from edible nuts. Mineral oil is made from petroleum. If I have to eat one, I choose Walnut oil! ;-)

In my studio, I have numerous clients who are concerned about finishes that may have contained toxic ingredients (as they define them). Still more that have asthma and other respiratory ailments that make them sensitive to fumes, or are extra concerned about anything they have in their homes.

To address these concerns, I offer a line of what I call "sensitive" finishes, for those clients who prefer a more natural finish on their woodenware. These include pure Beeswax, Walnut oil and Shellac thinned with a drinkable (from the local liquor store) alcohol, along with a few other exotic food based oils.

Whenever this subject comes up in woodturning circles there are always responses like: "All finishes when cured are food safe"... and similar comments. While that may or may not be true, it is irrelevant in the grand scheme of things. Why, because the client's opinion is the ONLY one that matters… Period. It's their money and their life, so they get to make the decision. I can talk till I'm blue in the face about cured finishes and their safety, but that carries no more weight than a grain of sand on an endless beach. If I do not satisfy the clients needs/wants, they look elsewhere. It's just that simple.

Having said that, I use and believe in lots of petroleum based finishes, as well as others that are toxic until fully cured. For those who prefer something else, I offer those as well, so everybody's happy. 

You could in fact use Shellac on a cutting board if you wanted to, but I would not choose it personally. Cured shellac can be liquified with alcohol, so unless you're mixing drinks on your cutting board and you spill some of your drinks on the board, you're probably going to be ok. Shellac is more of a film finish and as such, would not be the best choice (IMHO) for something like a cutting board that you use a knife on. Shellac does in fact dry, it can however become liquid again if exposed to alcohol, whereas most cured finishes are resistant to liquefaction once fully cured, lacquer being an exception… Shellac was used on furniture for many years and is still the preferred finish on some high end pieces. I like General Salad bowl finish and use it on some of my production bowls. It has a nice luster, that's not too glossy and it's resistant to staining. Very nice indeed!

As for the safety of Walnut oil with those who suffer nut allergies… Good question, my answer: Maybe.

I always ask my clients up front what finish they prefer and let them choose. The problem with saying it's safe for those with nut allergies is that some of these folks have *very* severe allergic reactions when nuts are even in the same room with them… I saw a documentary on TV that showed a small boy who could not even smell a peanut without going into shock. His mother said they could not have a single peanut in the whole house and his friends could never eat peanuts before visiting. Just smelling them on their hands was enough to send him to the hospital.

So, who knows. I let the client decide and offer them the choice, or if I'm selling spec bowls, I tell them what finish was used. If I had a client with a nut allergy, I would *not* advise them to use a nut based finish. Why take the risk (no matter how small) that some small child somewhere might be sensitive to any trace amounts of compounds in the oil? Better safe than sorry. They could always use beeswax, mineral oil, or nothing at all. Some of my clients want no finish whatsoever on their Treenware. Many years ago, this was standard practice, so that's another option for the nut allergy folks as well. YMMV. Take care and all the best to you and yours!

Steve Russell
EWW, WVP, EWWFS
THE Woodlands, Texas


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## MsDebbieP (Jan 4, 2007)

more great info. Thanks Steve! 
I've never noticed "walnut oil" in the grocery store. I guess I'll have to drive to "the big city" to see what I can find.

(re: peanut allergy .. just another story. In a day care in our area a grandfather, who had eaten peanut butter for breakfast) kissed his granddaughter goodbye in the morning. Somehow the kiss residue got transferred to another child in the daycare who was allergic to peanut butter and he ended up in the hospital that morning.)


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## DanLyke (Feb 8, 2007)

Steve, great info. Gonna have to go back and re-read the chemistry heavy post a few more times!

I too use walnut oil for my food safe finishes. I can get it at my grocery store (Ms Debbie, you might want to check your local health food store, I live in an area where the lines between grocery store and health food store are pretty blurred and I'd imagine that more rural areas don't have the amazing stock I'm blessed with), it doesn't bother my sweety who gets mouth sores from eating walnuts (not a true allergy, but a susceptibility), and it dries hard and is easily replenishable.


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## SPalm (Oct 9, 2007)

For what it is worth, I just bopped over to John Boos Cutting Boards for a look (www.johnboos.com). These are probably the most famous Yuppie boards around for use in the kitchen for actual cutting and chopping. So… this brings us full circle back to Tung oil mixtures.

Boos Mystery Oil

John Boos Mystery Oil Is Recommended For Care Of Tops And Blocks That Are Used As A Working, Cutting Surface. This Fine Oil Is A Mixture Of Mineral Oil, Linseed Oil And Tung Oil And Will Give Your John Boos Product The Same Quality Finish As The Factory.

We Recommend Oiling Your Tops Or Blocks Every 4-6 Weeks. This Food-Safe Oil Finish Keeps Your Blocks Looking New.

Steve


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## Russel (Aug 13, 2007)

Now that I've read all this, where do I go to apply for my chemistry degree?


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## Karson (May 9, 2006)

When I made my butcher block. Notice I said butcher block, not cutting board. The top was 6" thick and the apron around was 12" thick..

I used paraffin on the surface. I melted it with my wife's iron and ironed it into the wood. It went deep, but it did require replenishing, but it kept the meat juices from soaking into the wood.


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## TonyWard (Jul 20, 2006)

Steve Russell

An excellent post, thank you.

I've used raw Tung Oil for several years with excellent results. Having read your explanation I now understand the process, thank you.


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## sarge (Oct 23, 2007)

THANK YOU STEVE. I LOVE TO READ FROM PEOPLE THAT KNOW A FEW FACTS ABOUT A SUBJECT. MY QUESTION TO YOU,
MINWAX AND WATCO TUNG OIL, DO THEY CONTAIN TUNG OIL OR JUST A BUNCH OF OTHER FUN THINGS? 
THE MSDS FROM MINWAX ON THEIR TUNG SAID IT HAD 65% MINERAL SPRITS AND 0.2% COBALT 2-ETHYLHEXANOATE. (not a clue) BY WT.


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## brad (Sep 17, 2007)

Thanks for all the comments and information it has been enlightening, now can anyone speak to the application tricks you've learned using tung oil, as well as the products sarge mentioned in an earlier post.


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## SteveRussell (Jul 23, 2007)

Hello to the group,

MsDebbieP: Stories like that really serve to let you know how sensitive some folks are to certain nuts. In the same documentary I saw on the boy with the peanut allergy, they showed some flight attendants searching a plane for any peanuts. This same boy was taking an airline trip and they were afraid (mom and the airline) that if even one single peanut was on board the aircraft that he would go into shock during the flight. They practically tore the plane apart looking for peanuts in the back seat pockets and the floor cracks… Kinda scary. :-o They did say he made the trip without incident.

Dan: Walnut oil is one of my favorites for Treenware. I also like the fact that I can eat it right out of the bottle… 

Steve: I've seen some Boos cutting boards before… The finish is quite nice, but I personally like Walnut oil much better. I rarely use linseed oil for any finishing these days as it darkens considerably with age and is prone to yellowing. The yellowing of linseed oil is thought to be caused when conjugated unsaturated hydroperoxides are converted into conjugated unsaturated ketones.

These unsaturated ketones can produce long-chain colored polyenes. Additionally, if 1,4-diketones are formed during the drying, enol tautomers can react with trace amounts of atmospheric ammonia. This produces a substituted pyrrole, which can be converted into a colored product by oxidation, or by condensation in the presence of formic acid. Colored metal siccatives can also contribute to the discoloration and/or yellowing of linseed oil. To alleviate the yellowing, saturated aliphatic aldehydes are sometimes added to the oil.

Russel: Hehehe… 

Karson: Macrocrystalline Wax (Paraffin Wax) is a petroleum wax made from deoiled slack wax, which is derived by dewaxing base distillate lube oil streams of predominantly straight chain alkanes. Paraffin wax is brittle and has a low melting point between 46 and 71 degrees Centigrade. Paraffin waxes impart high resistance to moisture, so it should do well for you on your cutting block to prevent juices from soaking in to the wood. If you cut meat on this block, I would opt for an occasional salt rub…

Tony: No problemo, glad to help and that you did not fall asleep reading through my posts… 

Sarge: Most companies consider their finish formulations proprietary and thus reveal as little as possible about what's in them to consumers. Unfortunately, this makes it hard to make an informed buying decision…

MTO Finish is not a pure 100% tung oil as you have already found out. MTO is a blend of tung oil (actual % unknown, but I suspect it's very small) and an alkyd varnish resin, with a large amount (65%) of mineral spirits. The specific formula is proprietary and can not be disclosed, but it can be found out with GCMS and flash point testing. COBALT 2-ETHYLHEXANOATE is a drier and as such it helps to speed the curing of the finish. Do you mean Watco Butcher Block Finish???

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## cajunpen (Apr 9, 2007)

Wow - so do we use Tung Oil or not? I thing I am going to give it a go on my next project. Back to Brad and his original question - how do we apply TO? I have only used it one time and that was on a clock that I built almost 30 years ago. The finish still looks like the day I put it on. Cannot understand why I have not used it since, but I will be using it on my next project - if I can find the real Tung Oil )


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## SteveRussell (Jul 23, 2007)

Hello Bill,

Whether to use Tung Oil or not (for me) depends on the project… I use "pure" Tung oils and blended TO's all the time. Some of the blends are commercial blends, most are my own recipe. If you can give me an idea of what your next project might be (furniture, decorative item, turning etc), I'll be happy to help you if I can with application information. 100% pure Tung oil is easily obtained from suppliers like Lee Valley, or Liberon to name a few.

*Note:* "Pure" Tung oils will never produce a glossy finish, no matter how many coats you put on, or how long you wait. Pure oils will only produce a matte, or low sheen lustre. This matte sheen is a result of the natural expansion that takes place during polymerization. This expansion creates a very finely textured surface that appears to the naked eye as a matte finish. Pure Tung oils take a looooooooong time to cure, so if you really want anything more than a matte lustre, you should consider another product.

Unblended or pure oils typically include oils extracted from plants, nuts or petroleum. Examples of pure or unblended oils include; raw linseed oil, tung oil, kukui nut oil, macadamia nut oil and walnut oil. The labeling on the oil finish should include the words "pure" or "100 percent," or the oil may be blended with other ingredients. Tung oil is sometimes referred to as "China Wood Oil" by some suppliers.

If you want a glossy finish and you prefer Tung oil, you need to be using one of the polymerised Tung oil variants. Polymerized oils have been heated in an inert (oxygen-free) atmosphere enough to cause thermal polymerization to occur, but not enough to cause gelation. The resultant oil can be very viscous and is best applied in very thin layers. Two types of commonly available polymerized oil finishes are Linseed and Tung.

These specially processed oils provide faster drying and harder cured films with a more durable glossy luster. One challenge with using a Polymerized Tung oil is the colour of the product. It's a dark amber colour and this may be unacceptable to you if you are working with a light coloured timber. However, any timber that is of medium colour and darker should be a good candidate, as the colour of the finish will not significantly darken the preexisting colour of your timber.

So to better answer your question, it would help to know what your project will be, what lustre level you desire (glossy, satin/matte etc) and how durable the finish needs to be… i.e. Will it be handled regularly, frequently, infrequently etc. If you can provide a wee bit more information, I will be happy to help you. Take care and all the best to you and yours!

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## CharlesNeil (Oct 21, 2007)

Steve, A job well done my friend, its really good to see this much knowledge and expertise shared on a forum!
My personal thanks,I for one throughly enjoy


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## SteveRussell (Jul 23, 2007)

Hello Charles,

Thanks for your kind words…  Hopefully, it did not put too many LJ's to sleep. :-o I've always found that if you first understand the "why" (for example, why finishes cure the way they do), its much easier to understand the "how" (how to apply and perfect a finish). This philosophy has served me well through the years and it's allowed me to perfect and hone my finishing protocols to achieve consistently superior results.

I must admit however, that most folks probably don't want/need to know the why, they just want to skip to the how… That can work if you remain within tight application protocols, but when you encounter any variables outside of the "norms", you're in a sticky wicket as you try to figure out what went wrong (why the finish is still sticky after a week, why it's cloudy, or why it yellowed, etc). For me, delving into the "why," illuminates the "how"... Take care and all the best to you and yours!

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## brad (Sep 17, 2007)

OK, I'M GETTING READY TO MAKE A SLIDING STEP STOOL FOR LuLu (red oak is the material). I'm wondering if tung oil would be an acceptable choice of finish? Any opinions? If the answer is yes then what would be the finishing procedure?


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## Karson (May 9, 2006)

SteveRussell: I've used Penofin as an oil product because it has a version that has a UV block. They state that it is made with Rosewood Oil. I also notice that the company has been sold to a new buyer. What do you know about their UV finishes.


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## SteveRussell (Jul 23, 2007)

Hello Karson,

UV degradation and protection is a *very* complex subject that eliminates insomnia for most folks. A few of us, myself included, find the topic interesting, but then I love reading chemistry textbooks in the middle of the night and learning about various fungi and their effect on wood, so go figure…

I've used Penofin products in the past and they performed well. I'm not sure which version you are referring to (Blue label?) I've only used the Ultra Premium Red label, but the two are similar. Penofin in the blue label uses Transoxide pigments for its UV protection. I've been experimenting with manufactured UV resistant finishes, as well as making my own UV resistant finishes for about 10 years, so I know a wee bit about the subject. There are two schools of thought about how to reduce UV degradation… This is somewhat "deep", so please bear with me…

The use of UV stabilizers in manufactured finishing products works well, to a point. There is a ton of chemistry involved in determining the right type and amount of UV inhibitor to use. To complicate matters further, various types of UV inhibitors are available, each with their own particular drawbacks.

Two primary methods have been adopted to stabilize light/UV light: 1.) Competitive UV absorption by UV absorbers in the 290-350nm wavelength range and 2.) Trapping of the radicals formed during polymer degradation by radical scavengers using Hindered Amine Light Stabilizers (HALS). The two primary systems employed to reduce UV degradation are chemical and pigmented.

*Chemical:* Ciba Speciality Chemicals has a HALS stabilizer, which is a liquid amine stabilizer. It consists of an almost pure mixture of Bis (1,2,2,6,6-penatamethyl-4 -piperidinyl) sebacate and Methyl (1,2,2,6,6-penatamethyl-4 -piperidinyl) sebacate. It is used in automotive coatings, wood stains and industrial coatings and is a clear chemical liquid. It is VERY expensive. My research and testing indicates that these types of chemical stabilizers have great resistance to UV degradation initially, but tend to loose some of their effectiveness over long periods of time.

*Pigmented:* Pigments will prevent the UV from attacking both the coating system and the substrate. The best type is the old Zinc Oxide and the newer Titanium Oxide, which forms a complete block out. Other pigments of course will provide similar protection, but will obscure the grain. The Transparent Iron Oxides and Titanium Oxides have a very fine particle size and are therefore, transparent. The Titanium Oxides are also used in pharmaceutical formulations and are very expensive.

Transparent Iron Oxides are cheaper, but they are colored. However, the color can be used to enhance the surface of the timber. Since they are nearly clear, they do not obscure the grain. All UV systems protect both the coating and the surface that the coating is applied to, the substrate. However, in deciding which system to employ, one must consider the properties of the coating itself. Is it a varnish film on the surface, or a penetrating finish?

Thick finishes with UV protection (like marine varnish), do not really penetrate the wood surface deeply. Therefore, a breakdown of the coating allows deterioration of the wood surface, by allowing moisture to get under the coating. This delaminates the remainder of the finish. The penetrating oil type of finish (like Penofin) has the advantage of soaking into the wood and does not form a skin to lift. The varnish finish has certain advantages however, because the film thickness that penetrating oil finishes provide is substantially less than multiple coats of varnish.

The Oxides being inert, do not lose their effectiveness over time (vs. the chemicals), but if the surface coating deteriorates, the UV factor is decreased. So, it is a bit of a trade off, if the coating breaks down, the UV light will get through. Penetrating type coatings offer less breakdown of the surface coating, but do not provide as thick a surface film layer. So you can see that it is a long road to hoe, no matter which system you choose.

I have experimented quite a bit with blended finishes, in an attempt to strike a balance between the better overall coverage of the chemical systems and the superior long term performance of the pigmented systems. I have achieved excellent results with several protocols, but I think I could spend the rest of my life looking for the perfect UV resistant finish and probably only come close to that goal.

Since I fund experiments like these out of my back pocket, it can be a challenge to continue experimenting when the cost is so high for the stabilizers. However, it's in my nature to explore the "why" and "how" of things… It's as natural as breathing to me, so I continue experimenting… The results of my experiments over the last twelve years have allowed me to substantially improve my overall finishing protocols. My thin film polymerization testing was a real eye opener several years ago and the results of that testing have helped me for many years to produce better and longer lasting finishes on my turnings.

I try (as best as possible and within reason) to apply established scientific testing protocols when testing finishes in my studio. It has become a large part of my non-turning related testing and research and working under privacy agreements, has grown into me assisting some finish manufacturers with improving their existing products, as well as being in on the development and testing of other finishes before they are sold.

Looking back, I would have never guessed that this would be a part of my studio's work, but it's stimulating for me, as this is an area that I enjoy and have a strong passion about. If can help you again, please do not hesitate to contact me. Take care and all the best to you and yours!

P.S. It looks like I've given another $5.00 answer, when you probably only wanted the 5-cent one… Please accept my apologies in advance!

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## timber (Nov 12, 2007)

Hello SteveRussell,

After searching with google on Tung Oil I came across this topic and your postings. I was so impressed with your knowledge that I joined this site just to get your help with a wood project. It's not furniture but a gunstock and I hope this is not an inapproiate use of this forum.

About six months ago I purchased a new Sako 85 Hunter that is purported to have an oil finished walnut stock. It's rather dark with some contrasting long darker streaks and has a matte finish, pretty nice for a production rifle. After a recent hunt I noticed that I had slightly damaged (nicked) the stock is several places, revealing considerably lighter wood. I called Sako customer service and was told to just use 100% Tung Oil on the stock. They suggested that perhaps once a year I apply a light coat of the tung oil over the entire stock.

I've visited Lowes and Home Depot but their offerings (MinWax, Forby's, etc.) were not 100% pure Tung Oil. My questions are where can I purchase a small amount? Because of the darkness of the finished stock and the lightness of the nicks do you think the stock was stained or finished with a Tung Oil that had a stain mixed with it? I don't want to completely refinish the stock, just protect the damaged exposed wood. It doesn't matter if the 'scars' remain visible (just adds character) but I'd prefer to not have very light, contrasting 'scars'.

Thanks in advance,
Timber


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## SteveRussell (Jul 23, 2007)

Hello Timber,

Thanks for your kind words. You're one of the few that I did not put to sleep with this thread…  I'm familiar with the Sako 85 Hunter (sweet rifle), you have a fine rifle. Finding "100% Pure Tung Oil" can be difficult, but here is a source that has some in a 250ml/8oz can for $8.95 USD.

Lee Valley Tung Oil

At first glance, I would think the stock was not stained prior to being oiled, especially since Sako advertises the use of "premium" Walnut Stocks. One would think that a rifle costing £1,250 would use a stock with good colour. However, I've seen this happen before with some companies.

If the Walnut came in with a lighter colour, there may have been a base stain applied to "warm" it up prior to oiling. Best bet would be to call Sako and ask them if they ever use a stain on their Walnut stocks prior to oiling. If so, find out what they used and get some of it. You can apply it with a Q-tip to the nicked areas and then after it has dried, apply your Tung oil.

If they indicate they never use a stain on their stocks, the colour difference may be from the dark oil that penetrated the surface of the wood, which darkens it visually. If this is the case, a simple reapplication of the oil may sufficiently darken the timber so the colour matches. Either way, let me know how you get on. There are numerous tricks I can give you to make those nicks nearly disappear. Take care and all the best to you and yours!

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## timber (Nov 12, 2007)

Thanks SteveRussell. I'll give Sako a call. Hopefully they can tell me if they did use stain. The Q-tip suggestion is a good one. And thanks for the source.

From your answer it seems Tung Oil itself will impart 'color' to wood. Unless Tung Oil is quite dark Sako probably stained the Walnut first because there is considerable contrast between the stock and the knicks.

I've read that 100% Tung Oil takes time to dry. After I do a complete wipe down of the stock (once a year) how long will it be before the piece can be handled? My rifles are kept in an air conditioned space. How much do I put on?

I'll keep you posted on the process/progress.

Timber


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## gene (Oct 8, 2007)

I read, I laughed, I read, I laughed, And then I realised, Steve, just how knowledgeable and versed you are on this subject. My hat comes off to you on this subject. You really made my day with your replies on this post and made it interesting for me at the same time. I feel, I have learned something with this posting. Thank You!
God bless


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## Karson (May 9, 2006)

Steve. I'm still awake. But if I'm awake at 3 o'clock some morning I might go back and review this post. LOL.

I appreciate your response to my question on UV.


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## SteveRussell (Jul 23, 2007)

Hello again Timber,

Raw Tung oils take a loooooog time to dry. :-o Tack free can take 3-4 weeks in some cases, with full curing taking up to three month's to cure. Of course, when it's applied on a tiny nick, the long drying time may be a moot point.

You got me to thinking… It's been quite a while since I've had a Sako in my hands. :-( Many years ago when I was a wee lad, my next door neighbor was a custom gunsmith and I used to "hang out" at his workshop because I was interested in the shooting sports. He belonged to a private shooting range and we would go almost every day to test loads and guns he had worked on… He taught me how to shoot and how to reload over 35 different calibers, as well as how to work on rifles, pistols and shotguns.

I used to shoot a Sako when I was 11 or 12 and as I dust off the cobwebs for those sweet memories, I recall that my Sako had a very nice finish. Not too flat, not too glossy. Since you indicated that there is a marked difference in the colour of the Walnut in the nicked areas, I'm wondering if Sako used a Polymerised Tung oil (PTO), in lieu of a raw Tung oil? This might make sense as Polymerised Tung oils are very dark amber in colour, whereas raw Tung oil is quite a bit lighter in colour.

Polymerized oils are specially formulated by heating in an inert (oxygen-free) atmosphere enough to cause thermal polymerization to occur, but not enough to cause gelation. Another reason that PTO's might have been used is that they dry much faster than a raw Tung oil. Sitting around waiting for Tung oil to dry is about as fun as watching the paint dry on the wall. :-o Also, PTO's offer superior water resistance and will develop a medium to high gloss when buffed. Raw Tung oils will never develop more than a satin lustre.

My Sako had a medium gloss as I recall… So keep this in mind. You can still apply a Polymerised Tung oil with a Q-tip and it will dry much faster than a raw Tung oil. Thanks for the trip down memory lane…

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## SteveRussell (Jul 23, 2007)

Hello Gene,

Thanks for your comments… I'm full of all kinds of worthless information. I'm one of those rare people that sleep very little (usually 2 hours per night or less), so I've got a lot of time to work and research the topics I'm interested in…

I'm glad my posts gave you a chuckle! That's much better than putting you to sleep I guess.  Take care and if I can ever help you, please do not hesitate to contact me. Best wishes to you and yours for a safe, happy and healthy holiday season.

Steve Russell
EWW, WVP, EWWFS


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## SteveRussell (Jul 23, 2007)

Hello Karson,

Nah… You don't want to read these posts when you can't sleep mate. It might take 2-3 minutes to put you into dreamland. Zzzzzz, Zzzzzzz, Zzzzzz You want to read some of my material on fungi and its effect on cellulose fibers… Now that will put you into dreamland in a nanosecond or less, guaranteed!  Take care and have a safe and happy holiday!

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## timber (Nov 12, 2007)

Hi SteveRussel. My Sako 85 Hunter has a matte finish. When I first opened the box I could smell oil and it wasn't gun oil. I smelled the stock and it had this oily wood odor. It had a slightly oily/velvetly feel to it. My dealer and I concluded it had a traditional oil finsh, not the typical polyurethane. It was a pleasant surprise. The only other production gun I can think of that has a similar oil finsh is a Kimber 84 and 8400.

I can see where a minor touch-up on the knicks with 100% tung oil should not be a problem. But the recomendation is to wipe the entire stock down once a year. If I use it sparingly with a cloth will it still take months too dry? Again it will be stored in an air conditioned environment.

I'm hesitant to use polymerized tung oil because I'd prefer the stock to not take on a glossy look. But for practical maintenance to speed drying a slightly glossly look would be okay. Say something in the range of an 'eggshell' sheen would be fine. What do you think?

Timber


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## SteveRussell (Jul 23, 2007)

Hello Timber,

Apologies for the late reply… I had thought this thread had ended. Pure Tung oil applied in thin layers will dry much faster than if it were applied thickly, but it will still take a wee bit of time to dry. One trick you can use is to slightly warm the oil before application. This will make the application easier and it will also help it to dry faster. Use a Q-tip and do not apply too much. A few light coats are much better than one heavy application. Happy holidays!

Steve Russell
EWW, WVP, EWWFS
The Woodlands, Texas


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## jcash3 (Dec 15, 2007)

I'll keep this going. I use tung oil all the time, and it does take forever to dry IF you use just tung oil. A professional furniture maker who learned under Sam Maloof told me to do it this way. Mix equal parts 100% pure raw tung oil/ boiled linseed oil/ and Gloss Polyuerathan. Both the Poly and boiled linseed oil have dryers in them and will help the tung oil to plasticize. But it takes several usually 5 but as many as 7 or 8 coats to build enough for what i call the wow factor. After the last coat dries, I usually will put on a coat of wax to give a little luster. Check out my walnut and quilted maple tray for a view of it, also the mahogany jewelry box. The Gloss poly will not make the finish glossy, I assume because both oils dry as a satin or matte sheen. 
this is my favorite finish and on most projects that i make for just us i use it.


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## ErsatzTom (Dec 25, 2007)

How long do you let each coat dry?


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## jcash3 (Dec 15, 2007)

depends on the weather. right now it's in the 50's here so it may take up to 48 hours, that is bring it inside my house too. In warmer weather, spring and summer. It can take as little as 12 hours but usually 24 is a good time to wait. Also i've noticed that after you build several coats that the subsequent coats that you put on dry alot faster. not sure why. also i usually sand the wood to at least 320, but most of the time 400. then i rub the surface with 0000 steel wool, just to burnish and push the fibers back down and smooth everthing out. and then rub with steel wool between coats.


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## ErsatzTom (Dec 25, 2007)

Thanks for the info!


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## Jim Jakosh (Nov 24, 2009)

Steve, it is great to have you on board her on Lumberjocks. I got a real education this morning. I was a Physics major and did not do well in Chemistry but I love to learn the chemical make up of products. it helps a lot in decision making for finishes.
I was disappointed when I Googled Tung Oil and got this entry on Sawmill Creek which said that the Formby's Tung oil that I just used last night has NO tun oil n it!! Also it says it is an interior finish and Tung Oil used on ships to waterproof has to be an exterior finish. right. So should I get Pure Tung Oil and then use Poly over it for durability?

Also, for cutting boards, have you ever heard of Behandla salad bowl finish made in Slovenia? If so, what do you think of it?

Thanks, Jim


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## AlizaRGE (Jun 25, 2014)

I would love some advice for finishing an old kitchen hutch we have had for many years. It had some clumpy black wax on that we've been taking off with mineral spirits, but we've decided to go back to the actual wood and refinish. My question is what will give the wood a satin (less shiny) and clean finish that I can wipe down easily? I don't like polyurethane, and the countertop of the piece will come in contact with food from time to time, so I want it to be safe and wipeable with a sponge. I would like a finish I don't have to re-apply periodically.

Thanks for any advice and help.

Cheers!


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