# Raw/Pure Tung Oil finish - seeping issues



## LukeSommer (Jul 15, 2017)

Sorry if my first post offended anyone - EDIT:

I've used Raw/Pure Tung Oil (100% Pure Raw Tung Oil from Real Milk Paint company) many times with great results, but I'm finishing a table with Acacia/Rubberwood butcher-block type top and it seems that the large pores of the Acacia are giving me trouble. Would be interested in replies from anyone with experience finishing with Raw Tung Oil.

I followed the usual steps I always do: flooding with 50/50 Tung/Citrus Solvent for the first application, 75/25 for the 2nd, and about 85/15 or 90/10 for the third.

The second and third coats I also wet-sanded the oil in using 0000 Steel Wool and then wiped the sludge away thoroughly.

Between each coat, I wiped all excess oil off and waited for at least 4 days in between each. It took much longer to dry than I've ever experienced. But I know each coat was DRY (not of course CURED)-because between each, I sanded lightly with either 220 sandpaper or the Steel Wool, and the dust was a fine white powder - no gummy residue, indicating it was dry enough to add another coat.

(I live in FL, but I have the table inside where it is normally air-conditioned to 76 degrees, so the humidity is NOT high. To aid in the drying I turned the AC down to 72 so the air would be even drier.)

After each coat, I noticed that the oil was continually seeping out of the pores, so I was wiping it off about every 15-20 minutes for the first 8-12 hours, and then several times a day for the next 2-3 days. Again, I've never experienced this before, and I'm sure it has to do with the large pores of the Acacia.

Still, the first 2 coats went on fine and were completely dry before applying the next coat.

On the third application, I kept wiping and buffing as usual, and all was fine until the third morning when I checked it, oil had seeped out overnight and DRIED, so now there are dozens of tiny spots that are glossier than the rest of the table. They're not white-just glossier than the rest of the table-and you can only see them if you look at the table close to eye level in certain light, but the table is not as smooth where the dried oil is.

In an attempt to fix, I tried sanding with 0000 Steel Wool and then wiping down with pure Citrus Solvent - and then it was like a dam broke, and oil was seeping out of the pores all over! I was able to wipe that away, but the previously dried spots are still there - the steel wool and Citrus Solvent didn't touch them. Also, the Citrus Solvent seemed to dry out the rest of the table and make it duller.

On a small section of the table, I tried using a 3M white Final Finishing Pad and a bit of Tung to see if that would break up the dried spots, but that did nothing.

My plan was to do 1-2 more final coats, this time of 100% pure Tung - no Citrus Solvent. However, I don't want to do that until I know the best way to proceed.

Should I wait for several weeks to make sure the oil IN the pores is fully cured, and then sand and do a coat of pure Tung Oil, wet-sanding in various steps from medium to fine, to try to get rid of the spots?

Or, if I wait for it to thoroughly dry, and sand, and then just apply the pure Tung, will the Tung eventually build up so the rest of the table is as glossy as the spots, so it won't be noticed?

Or, if I wait for several weeks and apply Polymerized Tung-which has a glossier finish - will that bring the rest of the table to the level of gloss of the pores, making it uniform? I've never used Polymerized Tung before.

Any advice appreciated!


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## RichT (Oct 14, 2016)

> PLEASE: IF responding to this post, do NOT reply unless you know the difference between Raw/Pure/Unadulterated Tung Oil, Polymerized Tung Oil, and what is marketed as "Tung Oil Finish"-or tell me why Raw/Pure Tung Oil is bad, and other finished are better, or to sand everything off and use Poly or Varnish instead. I have used Raw/Pure Tung Oil (100% Pure Raw Tung Oil from Real Milk Paint company) MANY times with great success, and this is my first problem. I am mid-way through this project, and am only interested in replies from those with EXPERIENCE with Raw Tung Oil that address what I should do NOW to fix it.


That's not a great intro, telling people not to reply unless they know what they are talking about. You'd be amazed what you can learn from the occasional random reply.

I have extensive experience with The Real Milk Paint brand tung oil and citrus solvent, but since it sounds like you're the expert, I'm hesitant to reply. Best of luck figuring it out.



> Any advice would be appreciated!
> 
> - LukeSommer


LOL. Any advice? Didn't sound that way in your intro.


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## CharlesNeil (Oct 21, 2007)

Interesting ..

In the military I learned a valuable lesson…..........You have to know when to rise up and when to lie down.

It's nap time


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## RichT (Oct 14, 2016)

Well said, Charles. Hey, on a side note, I was re-reading some finishing articles in Woodworking Wisdom and Know-How from the Taunton Press, and realized you authored one of them. So, I was learning from you long before I discovered Lumberjocks. Who knew?


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## LukeSommer (Jul 15, 2017)

> I have extensive experience with The Real Milk Paint brand tung oil and citrus solvent, but since it sounds like you re the expert, I m hesitant to reply. Best of luck figuring it out.
> 
> - RichTaylor


-RichTaylor-YOU are someone whose advice I'd really appreciate hearing. It's just that I've read through so many forums where people ask questions like mine and get a hundred responses from people with no experience with Tung Oil saying "Raw Tung Oil sucks - sand it all off" or discuss how to use polymerized Tung Oils or "Tung Oil finishes" not understanding that those are completely different.

Thanks


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## crmitchell (Jan 13, 2013)

I'm going to take a stab at this from the logic perspective; I could be wrong. I haven't used tung in 30 years and I suspect the stuff back then was really tung.

I suspect the issue is the large pores of the acacia since you have not experienced this before and the rubberwood does not show the problem.. The larger the pores, the more oil is deposited in those pores, and the deeper the oil penetrates. My memory is that tung is one of the oils that cures by reactng with oxygen. More oil and deeper penetration would require far longer time to cure as the stuff below the surface is oxygen starved.

I had an antique mahogany bed that required forever for the tung to cure, and it oozed for days like yours.


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## LukeSommer (Jul 15, 2017)

> I m going to take a stab at this from the logic perspective; I could be wrong. I haven t used tung in 30 years and I suspect the stuff back then was really tung.
> 
> I suspect the issue is the large pores of the acacia since you have not experienced this before and the rubberwood does not show the problem.. The larger the pores, the more oil is deposited in those pores, and the deeper the oil penetrates. My memory is that tung is one of the oils that cures by reactng with oxygen. More oil and deeper penetration would require far longer time to cure as the stuff below the surface is oxygen starved.
> 
> ...


Thanks, Carey. Sorry for the confusion - "Rubberwood" is another name for Acacia.
I suspect the same. Any thoughts on whether continuing at this point would build up the sheen to the point where the spots would blend in, or should I give it a few weeks for the pores to be fully cured and then wet-sand the oil in on the next coats?


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## TungOil (Jan 16, 2017)

You could try calling the Real Milk Paint company for advice. I'm sure they have a customer service department that might be able to help you.


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## crmitchell (Jan 13, 2013)

Thanks, Carey. Sorry for the confusion - "Rubberwood" is another name for Acacia.
I suspect the same. Any thoughts on whether continuing at this point would build up the sheen to the point where the spots would blend in, or should I give it a few weeks for the pores to be fully cured and then wet-sand the oil in on the next coats?

I would give it a few weeks. Raising the temperature would help, but don't be surprised if the rate of weeping increases a bit.


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## kelvancra (May 4, 2010)

Good thread. I used to buy my pure, polymerized tung oil for around thirty-four a gallon out of Winthrop, Washington. I loved the stuff. Though not an idea finish for things requiring durability, I test drove it on a 10-22 stock and, a few coats down the road, it was beautiful.

I've long been aware tung oil and BLO reacted with oxygen to cure (a few people used it to remove oxygen from stored items), rather than merely gas off the solvent. Never thought about the matter of deep penetration, by way of pours, being a problem, but I will consider this potential problem using it when that could be a problem.

I presume the problem would be merely reduced using polymerized and treated (metals) oil, but would still be a problem.

I have to wonder what would happen if you could place the item in a vacuum bag and pressurize it, like they do with hyperbaric chambers, rather than applying a vacuum. If the top layer of oil hasn't fully cured, it seems the pressure might push the air, thus oxygen, into the wood.

If I went that route, I test on a sample, since air in wood is a pain, as you likely know, when trying to get a top coat on something.



Curious and confused - my brother gave me a dead tree from his back yard. He said it was acacia. When I cut, planed and sanded it, it reminded me of [beautiful] walnut, but more golden brown. When I run rubberwood and acacia, I get two completely different results. The acacia looks like what I got and described, but not so the rubberwood.

To make matters worse, a guy at our turning club brought an olive wood bowl, which looked like it could have passed for acacia. Running the two terms together produced results indicating there is acacia olive wood.

Any insight?



> Thanks, Carey. Sorry for the confusion - "Rubberwood" is another name for Acacia.
> 
> - LukeSommer


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## LukeSommer (Jul 15, 2017)

> Good thread. I used to buy my pure, polymerized tung oil for around thirty-four a gallon out of Winthrop, Washington. I loved the stuff. Though not an idea finish for things requiring durability, I test drove it on a 10-22 stock and, a few coats down the road, it was beautiful.
> 
> I ve long been aware tung oil and BLO reacted with oxygen to cure (a few people used it to remove oxygen from stored items), rather than merely gas off the solvent. Never thought about the matter of deep penetration, by way of pours, being a problem, but I will consider this potential problem using it when that could be a problem.
> 
> ...


Thanks, Kelly, if I had a vacuum bag I'd try it! And you're right - Rubberwood (which is what I have) is different from Acacia. I think the furniture maker used the terms interchangeably, which is where I got the false info. Rubberwood is also known as is also known as "Parawood" and it's used today in a lot of imported furniture. I've bought several pieces because it's an affordable way to get unfinished solid wood that you can then finish yourself. I finished a dresser made from Rubberwood with stain and varnish, and it turned out great. The pores didn't seem to be an issuee with that one…


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## LukeSommer (Jul 15, 2017)

> Thanks, Carey. Sorry for the confusion - "Rubberwood" is another name for Acacia.
> I suspect the same. Any thoughts on whether continuing at this point would build up the sheen to the point where the spots would blend in, or should I give it a few weeks for the pores to be fully cured and then wet-sand the oil in on the next coats?
> 
> I would give it a few weeks. Raising the temperature would help, but don t be surprised if the rate of weeping increases a bit.
> ...


Sorry Carey - Rubberwood and Acacia are not the same after all. See Kelly's comment below and my reply. The table I have is Rubberwood.


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## LukeSommer (Jul 15, 2017)

UPDATE: I sanded everything completely off. The spots disappear when I sand them off, but reappear within about 20 minutes. I then sand again, and each time there are fewer oil spots rising up. Now, they are almost entirely gone. Should I wait until they completely stop appearing after I sand? Would this mean they are finally dry?
Also: since the pores are obviously really deep, I'm wondering if I should perhaps just apply a very thin coat of 50/50 Tung Oil/Solvent (wipe on with a rag) instead of flooding the surface until it stops absorbing and then wiping, like I've always done in the past? 
I'm concerned that if I use the usual method, the same thing will happen again (I don't really understand why the oil keeps coming back up but it must have something to do with the extreme depth of the pores in the Rubberwood/Parawood)...


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## ArtMann (Mar 1, 2016)

Your experience with 100% Tung oil is the same as the experience I had. I gave up.


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## kelvancra (May 4, 2010)

Just curious, why raw tung oil rather than polymerized?


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## LukeSommer (Jul 15, 2017)

> Just curious, why raw tung oil rather than polymerized?
> 
> - Kelly


That's what I first started using and have had good results in the past. Do you think polymerized would be better for deep-pored wood? Is it similar to Raw in ease of refreshing (no stripping necessary - just sand lightly and re-apply?)


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## jdh122 (Sep 8, 2010)

Polymerized is exactly the same as raw tung oil in terms of ease of refreshing. You can just re-apply another coat whenever you want. I use it all the time as my go-to finish. I especially like the Lee Valley polymerized tung oil, as it is high-luster (you can mix it with their no-luster tung oil to get more or less shine). I have used raw tung a few times (Circa 1850 Tung Oil) and did not have the type of problems you mention (on birch, maple, oak) but I do find the wait to be very long and the finish a little bit dull (like BLO, seems to need a coat of wax to look right).


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## dbray45 (Oct 19, 2010)

When I use Tung oil, I plan it so I can set it in the sun out doors for 4-6 hours. I actually do that for oil based poly if I can.

For my kitchen counter tops, 4 coats of tung oil and 4 coats of poly, each rubbed down, the application was inside and the drying was outside. It is amazing what the sun does to dry and cure finishes.


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## LukeSommer (Jul 15, 2017)

> Polymerized is exactly the same as raw tung oil in terms of ease of refreshing. You can just re-apply another coat whenever you want. I use it all the time as my go-to finish. I especially like the Lee Valley polymerized tung oil, as it is high-luster (you can mix it with their no-luster tung oil to get more or less shine). I have used raw tung a few times (Circa 1850 Tung Oil) and did not have the type of problems you mention (on birch, maple, oak) but I do find the wait to be very long and the finish a little bit dull (like BLO, seems to need a coat of wax to look right).
> 
> - jdh122


That sounds good. Problem is I can't wait for a mail order. I'll be leaving for for 3 months in a week and wanted to get at least a coat on the table before I go to protect it, as some friends will be staying here while we're gone. Do you have any opinions on Waterlox and whether that might work here?


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## LukeSommer (Jul 15, 2017)

Any opinions on whether something like Waterlox would have the same problems? I've always used Tung because I wanted something easy to maintain (so stripping or sanding to refresh) in the event of water rings, etc… from what I read about Waterlox it's easy to refresh the finish when needed… any thoughts on whether I'd have the same issues with bleed-back due to the large pores of the wood with that?


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## LukeSommer (Jul 15, 2017)

> When I use Tung oil, I plan it so I can set it in the sun out doors for 4-6 hours. I actually do that for oil based poly if I can.
> 
> For my kitchen counter tops, 4 coats of tung oil and 4 coats of poly, each rubbed down, the application was inside and the drying was outside. It is amazing what the sun does to dry and cure finishes.
> 
> - dbray45


Thanks. I don't want to use poly because it was on some butcher block countertops in a house we bought and it was awful - plastic-looking and sticky. Apparently people used harsh cleaners on it and that degraded the poly into a sticky mess. While WE wouldn't do that, the house is a vacation rental, and although we have signs saying not to use harsh cleaners, people will. We finished it in Raw Tung and it worked out beautifully (it's Maple so no issues with large pores). If someone does use something harsh on it, it will be easy to refresh the finish - just sand lightly and reapply. For the table, I want something similarly easy to maintain. Do you have any opinions on Waterlox and whether it would work for the Rubberwood table? From what I've read it's easy refresh, although you do have to wash it with TSP (tai-sodium phosphate) first.


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## TungOil (Jan 16, 2017)

> Any opinions on whether something like Waterlox would have the same problems? ..... any thoughts on whether I d have the same issues with bleed-back due to the large pores of the wood with that?
> 
> - LukeSommer


I used Waterlox Original Sealer/Finish on a set of oak cabinets last year, I had no issues with bleed back. It is a tung oil based product, so you probably would not have any compatibility issues, but if I were you I'd contact Waterlox customer service to get their opinion. They have been helpful in the past.


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## kelvancra (May 4, 2010)

As the resident Not Expert, I'd offer, a tung oil based poly is far removed from raw tung oil. Products like Waterlox have resins, solvents and hardeners added to polymerized tung oil, similar to how Varithane polyurethane is made, but with linseed oil for the base.

Looks like the question about the difference between polymerized tung oil and raw tung oil may have been answered. It remains both raw and polymerized tung oil hardens by way of reaction with oxygen. Since polymerized tung oil is already off and running, problems with it being slow to harden in areas where it has deeply penetrated should be less, but could still happen.

As to applying future coats, I would see no reason to strip an existing layer, but I would scuff. That could be done with a Scotchbright pad or whatever is easiest.

When I applied three or four coats to a gun stock (hey, I was playing with it anyway), it turned out beautifully just adding coats a day apart.



> Any opinions on whether something like Waterlox would have the same problems? ..... any thoughts on whether I d have the same issues with bleed-back due to the large pores of the wood with that?
> 
> - LukeSommer
> 
> ...


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## RichT (Oct 14, 2016)

Great post, Kelly. I'm struggling to understand polymerization of oils. For example, The Real Milk Paint brand of pure tung oil refers to their product as "naturally polymerizing," whatever that means. I know some oils are treated with hardeners, and others with heat.

Anyway, I was reading a great book titled The Furniture Bible where the author writes: "*LINSEED OIL*: Often called boiled linseed oil (raw linseed oil is seldom found in stores other than art-supply resources), this self-polymerizing product is made of heated and treated flaxseed oil. It has been used for millennia as a finish and as a medium for paint and varnish." (Excerpt From: Christophe Pourny. "The Furniture Bible: Everything You Need to Know to Identify, Restore & Care for Furniture.").

There's your "self-polymerizing" term again.

So, can pure tung oil that has been heat-polymerized still be called "pure?" We all know that the "Tung Oil Finishes" aren't real tung oil, but where is the line drawn?


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## kelvancra (May 4, 2010)

Polymerization is how tung oil and linseed oil harden. The metals and things just speed it up.

If you just run the term polymerization, you'll find all sorts of ramblings about cross linking and so forth. In the end, it is what makes -hardening oils- hard. To my knowledge, it all occurs by way of reaction with oxygen, which is why some have even used it to remove oxygen from storage containers.

I believe polymerized tung oil is still pure, as long as no additives have been dumped into the product. All it does is put it in the category of boiled linseed oil (which is not boiled, but has oxygen pushed through it, causing it to "boil"). Of course, in addition to thickening the product by way of running oxygen through it, it can have the hardening metals added, or not.

To twist things a bit more, look into long and short oil finishes, which is a way of describing finishes with more or less hardening oil added. With more oil, the finish is more flexible, so will tolerate shifts of the wood it's applied to (think marine finishes). The high end finishes use tung oil, rather than linseed oil.

Varithane could be called a short oil finish.

As you said, most so called tung oil finishes are not. Including Fromby's, which, at last check, used boiled linseed oil.

_
Did I just muddy the water, or did my ramblings help?


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## wapakfred (Jul 29, 2011)

Luke, "poly" is a resin, not a finish…we have just convoluted our language to use it that way. In common usage, "poly" is an oil based varnish and I agree with you about the appearance. It's one of a few reasons why I don't use it. But other varnishes (Waterlox Original is one) are made with different resins that don't have that plastic look. Waterlox Original is a tung oil/phenolic resin formula and is very good…quite durable although the darkest of varnishes. there are also some alkyd resin varnishes that are very good. P&L 38 is a soya oil/alkyd resin, and SW Fast Dry Oil is a linseed oil/alkyd resin finish. Both are excellent, the SW has a little more amber than the P&L (my favorite). My suggestion would be to consider any of these as alternatives.


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## RichT (Oct 14, 2016)

> Did I just muddy the water, or did my ramblings help?
> 
> - Kelly


Nope, your ramblings are very clear. I hadn't heard of long and short oils. I'll have to dig deeper into that. It wasn't so much the concept of polymerization that was confusing (even though my opening sentence made it sound that way), but the descriptions.

One was whether polymerized tung oil is pure, and I agree with you about that. The one that seems odd to me is the Real Milk Paint oil that their web site refers to as "naturally polymerizing." That seems to me to be the same as referring to ice cubes in your tea as "naturally melting." In other words, they are making it sound special that it does something it would do anyway.

As usual, I'm overthinking it.


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## kelvancra (May 4, 2010)

I went to the Real Milk Paint web sight to try to find info that would help you and I left that site web page with a solid impression it was more about pushing product than fact. In fact, it seemed some of the info pushed the contradiction line pretty hard.

The stuff I used to buy was pure (no solvents or metals) and many of the other marketers sold similar products. You had to buy the metal additive separately and the little bottle came with directions.

In the end, remember I'm just parroting things I picked up over the years and my scientist background is limited to experience [temporarily] ruining projects.


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## kelvancra (May 4, 2010)

Fred, I don't know if I'm interpreting your statement wrong, but it's my understanding finishes like Varithane polyurethane is not just resin. Rather, it is polymerized (thus the poly name) linseed oil with resin added, along with solvents and UV protectors like titanium or other materials. Hey, it's on the Net, sooo

One of the pine tress my wife planted three or four decades ago came down in a big wind. I saved about two gallons of the pitch and I'm going to take time to clean it and play with it just to see what happens when I add a bit to BLO. Should be a fun experiment.

Currently, I've been playing with an equal mix of pine tar, BLO and turpentine for exterior surfaces, because surface coat finishes are both so undependable and must be stripped.

I was thinking of adding a little resin to that mix too, just to see what I get. Without the resin, I get a lot of penetration in dry wood. As long as the stuff keeps disappearing into the wood, I keep adding. At the end of the day, that leaves the potential for the kind of problem this post was started for, but it hasn't reared its head, yet. That may be because the surface layers are hardening, so the problem isn't apparent.

My big concern is whether the pine tar would stain, for example, white pants, when someone sits on a picnic table bench. That hasn't proven to be a concern, if the mix is given a few days to harden.

If the hardening oil under the outer lay is slow to polymerize, that could have a positive effect on old wood - it would swell the wood, reducing cracks and splits.

I slathered mineral oil on a end grain butcher block with a lot of separation and cracks or splits. I kept flooding it, then left the last puddle coat alone. When I came back, in a few weeks, I was, pleasantly, surprised to see the oil had swollen the wood and all the cracks, splits and separations were no longer visible.

[end of rabbit trail]



> Luke, "poly" is a resin, not a finish…
> 
> - Fred Hargis


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## wapakfred (Jul 29, 2011)

Kelly, varnish is a compound made by cooking resins and a drying oil (linseed, tung, soya, and less often some others) together to form the new compound varnish. So varnish is neither "poly" (or whatever resin) or oil…..it's varnish. Somewhere (I blame Norm) the name "polyurethane varnish" got shortened to "poly", and while oil finishes were the most commonly used, that wasn't too bad. But now we have some other finishes that are sometimes included in that ill-defined naming convention. There are questions posted that start with "I used poly, and this happened", only later you might learn that it was a waterborne finish used (typically primarily an acrylic with a small dollop of urethane added for marketing reasons) and any answer that had assumed it was an oil based varnish could really be a problem if the OP tried whatever was suggested. BTW, you were correct about long and short oil finishes, it's the amount of oil in the mixture they cook that determines it, and long oil formulas are labeled "spar" varnish. So, your conclusion that Varathane (or any other varnish) isn't just resin is correct, my point being that "poly" is just one of the 2 main ingredients used to make some of the varnishes. But calling any finish "poly" at this point isn't really very specific. Kinda like the description "tung oil" when it can mean so many things that it takes a sentence or 2 to explain you mean the real thing (as Luke did in the beginning). I think maybe i should have said: "Poly is a resin, not a finish…you probably mean varnish"


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## RichT (Oct 14, 2016)

> I went to the Real Milk Paint web sight to try to find info that would help you and I left that site web page with a solid impression it was more about pushing product than fact. In fact, it seemed some of the info pushed the contradiction line pretty hard.
> 
> - Kelly


I appreciate all of your input. I like to experiment with different finishing products and techniques. Most of them will never wind up on a project, but I enjoy the learning process.

Regarding the Milk Paint brand of tung oil, it's a fine quality product, and the one I use exclusively. I've used it on cherry, bocote, chechen and other hardwoods with excellent results. At the end of the day though, it's just tung oil, so I guess they have to come up with ways to embellish its description on the web site so it stands out from the other quality tung oils that are available.

I plan to order cans of a couple of different oils from Sutherland Welles to see how they perform. Maybe I'll prefer polymerized. Always fun to try new stuff out.


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