Tacky tung oil

M

mjes92

New member
Refinished a pellet gun stock for practice. Used a leather dye to get the desired black color. Liebings brand as recommended in a older thread. Then applied 4 coats of Watco tung oil. The problem I'm having is the finish remains tacky after curing for 4 weeks. My first time working with Tung oil. Is this to be expected?

Getting errors trying to upload photos.
 
That's not my experience with tung oil. Perhaps you applies it too thick, perhaps not. It could be contaminated? It could bre about anything!
 
You may be assuming the wrong thing ! Though called "Tung oil" it may may be some tung oil and the rest linseed oil.Marketing , you know.
In any case linseed oil for sure has to be done layer by layer. In gunsmithing school we were taught to apply a good layer of linseed oil , wait an hour or two then then briskly rub off excess oil.Then wait 24 hours and repeat.Do this 4 or 5 days to get the number of layers .
Linseed oil gets harder and more water resistant as the oil oxydizes and polymerizes over time.
I would remove what you have and procede as I mentioned.
 
Wash off the Watco tung oil with mineral spirits, then apply Formbys tung oil
one coat at a time...using 0000 steel wool between each coat lightly.
 
I've tried Watco, and didn't like it at all. I actually gave away two pint cans, one full. I had similar problems, and after the fourth coat, it remained tacky.

I stick with Tru-Oil because it works every time. There is another brand, named Pro-Custom and Gun Sav'r spray, by Chem-Pak, that works well. If you don't like a shiny finish, you can use 0000 steel wool or rotten stone to dull it.
 
Birchwood-casey Tru-oil from walmart. Wonderful stuff, based on tung oil. Thin coats dry in hours (as long as your humidity is low).

No muss, no fuss. Stands up to bbl cleaners just fine.
 
I work wood, and oil finish is my favorite. For tung oil I only use the pure tung oil from Rockler. Most canned products that bear "tung oil" in their names have additives.

-TL
 
"...applied 4 coats of Watco tung oil..." If you did that all in one day that's why. Tung oil, (The brand doesn't matter, but Tru-oil is not pure tung oil. It's more like Minwax's Tung Oil Finish. Has other stuff in it.) needs to be rubbed in(not slathered on and left to dry like BLO.) thin coats over several days with 24 hours drying time between coats.
Like Smoke & Recoil says, mineral spirits is is your friend. Think clean, lint free, cloths to apply tung oil and wipe off the excess.
And go to your public library and get a book on finishing fine furniture. Same products and techniques for firearm stocks.
 
I would do one or both of the following:
1. Try some UV light. Take the stock(s) outside and see if sunlight will cure the finish. Many of the "Tung Oil" wiping varnishes have compounds in them that require, or at least cure better when exposed to UV light. Depending upon how tacky the finish is, you may want to consider some kind of dust control measure.

2. Dump the Watco, strip the finish, and start over. I haven't used any on a gun stock, but I have been thoroughly unimpressed with the Watco finishes that I have used on other projects. For alternatives, the above suggestions should all be good.


My own preference is for Pure Tung Oil diluted with mineral spirits (8-20 coats, depending on the wood), then sealed with a "Tung Oil" wiping varnish. I'm currently using Hope's Pure Tung Oil, but can't really recommend it. Cure time is ridiculous - up to several weeks per coat if applied undiluted. For the wiping varnish, I prefer Formby's Tung Oil Finish; but they no longer have many choices for sheen. If you don't like gloss or semi-gloss, the sheen would have to be knocked back after the final coat.



(I am not a gunsmith. I just work on my own.)
 
Oil finishes (including solvent-based varnishes) react with oxygen to cure as it makes them polymerize (free-radical cross linking).

Regardless of the type of oil or solvent-based oil / varnish blend, adding about 5-10% thinner helps because as the thinner evaporates out of the oil, it causes oxygen to mix into the finish. This speeds up the polymerization process, while ensuring the finish is applied in a thin coat.

If you want to speed up the drying process, you can use varnish makers and painters (VM&P) naptha as the solvent. It is a more volatile solvent than mineral spirits and evaporates faster.

You can also add a very small amount of Japan drier. Driers can be purchased at most specialty paint stores and I have even found them at stores like Home Depot.

Mix the drier into the solvent to be used to thin the oil or varnish, and then mix that into the oil or varnish. You need only about 1/10 ounce of drier to 8 ounces of finish. In 4 ounces of oil or varnish you would only need about two large drops of drier.

Only mix up the amount of finish + drier you are going to apply for that coat. Do not return the finish with drier back to the original container as it will cause the remainder of the container to harden

I have done a lot of wood finishing and refinishing and always keep a can of Epifanes "accelerator" specifically to add to both varnishes and oil finishes to speed up drying.

The driers and accelerators promote free-radical, autoxidation of the oils or varnish with air causing chemical cross-linking and drying. Either the drier or accelerator will cause a slightly harder finish as they ensure that 100% of the oil or varnish has polymerized.

If you would like to know more about wood finishes, I would suggest getting a copy of, "Understanding Wood Finishing," by Bob Flexner.
 
Except for the pure Tung Oil (which I buy at Woodcraft), most of the finishes mentioned are wiping varnishes. I've used Watco Danish Oil, which is slow to dry but does penetrate pretty well. I've used Minwax Antique Oil, which will dry on a one coat per day basis. It looks great and wears well, but is not truly waterproof. Most wiping varnishes, and Tung Oil, and Hand rubbed linseed oil finishes are not waterproof. The last and best gun stock finish I've used is Waterlox Original in satin. It fills wood pores, self levels very well, builds a finish layer, wears well, and is waterproof. But...slow to dry and takes a few weeks to finally cure.

If in a hurry, use the Minwax Antique Oil. If not, I'd use the Waterlox, which is not cheap.
 
Bob Lexnor's book, Understanding Wood Finishing (mainly furniture finishes; no gun stock finishes) is the one I use as my finish bible for reference. He rates both raw linseed oil and boiled linseed oil as "poor" for protection. They have poor water resistance, which is the reason they get water spots easily, and they aren't hard enough to resist abrasion well. This is why a lot of old timers wiped new linseed oil onto their gun stocks after an outing. It replenished them.

Flexnor says pure tung nut oil also has poor water resistance until you build up five or more coats. He says you must sand between each coat to achieve adequate adhesion between layers, and each application must have absolutely all excess carefully wiped off. Despite the resulting thinness of the layers, they still take at least several days to a week to dry. Due to this thinness and the sanding, the first three or so layers look flat and blotchy. At five layers it finally takes on a continuous sheen and begins to offer moisture protection. However, he says it remains a relatively soft finish that is scratched easily, so the mechanical protection is poor, even if the moisture protection is better than with linseed. Flexnor says pure, plain tung oil is rarely used as a finish by itself (in furniture making) for these reasons, but is a very successful supplemental component in other finishes.

Polymerized Oils: Either of the above oils and others can be "polymerized", after which they dry faster and provide excellent moisture resistance properties and mechanical strength. Polymerizing is cross-linking of molecular chains in the finish to form longer chains that interlock with one another until, as polymerizing completes, a hard plastic-like material is formed. Polymerized oils are actually only partially polymerized as sold. This makes them thick, so they are sold in a thinned form, and not pure. They are made by placing an oil in an oven without oxygen or with a controlled amount of oxygen, and heating it up to several hundred degrees for a period of time. This initiates the polymerizing process in a controlled fashion, leaving less polymerizing remaining to occur later for it to actually dry. It pre-lengthens the molecular chains to a controlled degree, so that when drying occurs there is a minimum molecular length throughout the oil and final polymerization commences with a big head start and with a lot fewer molecules to link than when a larger number of shorter species are in the mix.

Birchwood Casey Tru Oil is a polymerized oil, and Flexnor rates it "excellent' protection both for mechanical toughness and water resistance. Being partially polymerized, it cures (completes polymerization) faster than the raw or even boiled pure oils do. Flexnor's book is mainly about furniture finishing, but he recommends Tru Oil as a good finish for that purpose. There are other polymerized oil finishes available, too, of course, and you can get them either with gloss or satin or flat final finishes from Sutherland Wells and in other brands.

The Watco and Deft Danish Oils and other such finishes are actually blends of oils and varnishes and often have polyurethane components to improve mechanical strength. Because they contain some amount of raw oil, their protection rating is only medium in Flexnor's book.

The other finish he gives excellent protection ratings to are wiping varnishes. Many of these are polyurethane-only, though, and are not natural oil finishes. Watco Wipe-on Poly, for example, is a wiping varnish, where their Danish Oil is a oil/varnish blend and not a true wiping varnish.

Bottom line, if you like the appearance of natural oils, but want the best protection, get a natural oil that is sold as a "polymerized" oil.
 
I used the BC Tru Oil exclusively for prolly 40 years on a lot of firearms. Still like it a lot.

Here in the last 10 years or so, I started experimenting with Min Wax Spar Urethane in a semi gloss. It produces a hard and durable finish that is water proof and UV resistant.

I hand rub and usually end up with somewhere between 7-9 thinly applied coats when finished.

The last one that I did was a Rem 788. The owner picked it up and couldn't believe the appearance. He left with a tear in his eye after showing it to his wife and commenting "it's beautiful".
 
Tung oil, and a few other oils suitable for wood finish, polymerizes when cured. Oil finishes seldom are as good as man-made products like polyurethane in terms of durability and water resistance. But they bring out the characters of wood in their own ways, such that woodworkers are willing to trade off. Oils finishes are also easy to repair.

I use the so called "fat over thin" method to apply tung oil. One coat every 24 hours, with decreasing turpentine proportion, till I have 5 to 10 coats. I apply each coat generously. Wait 30 min and wipe off the excess.

The other oil finish I favor is walnut oil, available from grocery stores for making salad. It polymerizes pretty well too.
 
The other oil finish I favor is walnut oil, available from grocery stores for making salad. It polymerizes pretty well too.
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That's really not the type of walnut oil you want to use for a finish. If you want to use walnut oil, my suggestion is to get Mahoney's Polymerized Walnut Oil.

Mike Mahoney is a bowl turner and developed the finish for his bowls and sells it to other wood workers. It is a food-safe finish. I use it on cutting boards. Once you have the wood fully saturated and the pores filled in the board, all you have to do is wash the board and apply a new coat about 2-3 times a year.

The way to apply it is to flood the surface and let it sit for an hour and then wipe it off. With cutting boards, the first 3-4 coats will fill the wood pores with this method.

One of the things Mahoney's will do with cracks in cutting boards is cause the wood to swell and the crack will close. I have "rescued" several cutting boards with cracks up to 1/16-inch wide by filling the cracks once a day with Mahoney's oil over about a one week period. At the end of 7-10 days the crack appears as a faint line because the wood has swelled shut. I have never had a crack reopen in a board after it has been treated. It is, in effect, a permanent repair.

Mike Mahoney also has an oil/wax finish available. It is a mixture of Mahoney's Walnut Oil and beeswax. I have used the oil/wax on wooden salad bowls and on soapstone countertops as it is the perfect finish for those materials.
Oil finishes seldom are as good as man-made products like polyurethane in terms of durability and water resistance.
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I would disagree with that statement. Polyurethane is quick and easy to apply but it is not superior to something like Epifanes varnish or Waterlox. Both Epifanes and Waterlox are a tung oil / phenolic resin finishes. These are far different than a standard alkyd-based clear "varnish" finish.

Polyurethanes (especially water based polyurethane) have supplanted traditional oil varnishes in industrial uses because of VOC considerations, and quicker drying times. They make a very good finish for kitchen cabinets and furniture as they are easy to apply and dry rapidly, while still giving good water resistance.

One of the great features of polyurethane varnish finishes is the wide range of surfaces: dead matte, satin, semi-gloss, and glossy. You cannot find that range of finishes available in an oil varnish finish.

One of the failings of polyurethane varnish finishes is very poor UV resistance. They become cloudy under heavy UV exposure and often yellow badly.

Other urethane based finishes that use catalysts (mainly automotive and industrial paint finishes) are a totally different type of finish and are meant as surface finishes on impermeable materials. For those uses, I would agree that urethane is a better finish.

Waterlox is a little bit thinner than Epifanes varnish and is easier to use as a wiping finish, but either will be superior to a polyurethane varnish on wood.

There are some additives in Waterlox that make it different than Epifanes. Epifanes is a true varnish and requires sanding between coats in order for the next coat to adhere. Waterlox will adhere to itself and does not require sanding - although, most people generally lightly sand between coats to eliminate dust nibs and other surface imperfections.

Both Epifanes and Waterlox need to be thinned prior to use. For Epifanes, the preferred thinner is the Epifanes Thinner that is formulated specifically for the varnish. Waterlox really needs a thinner with more solvent power than mineral spirits. Either turpentine, VM&P naphtha, or Epifanes Thinner will work much better than mineral spirits.

Polyurethane never penetrates as well as either Epifanes or Waterlox and the final surface film is not nearly as hard. That's why polyurethanes have not supplanted varnishes like Epifanes for bright work on boats or, in the case of classic wooden boats, varnishing the entire boat.

Both Epifanes and Waterlox benefit from using Epifanes Accelerator in small quantities. The accelerator actually seems to help the consistency of the liquid by reducing the surface tension (making a smoother coating) and also guarantees that the finish will be cured within 24 hours.

I have used the accelerator with Waterlox under rather extreme conditions of 90+ degree heat and very low humidity. In those conditions, I have been able to put on two coats per day as the accelerator will fully cure the Waterlox in about six hours.

It would not be advisable to do that with a brushed finish as the varnish may not have time to fully level. However, with a wiped finish there is no problem as the finish never has to level.

An easy to apply, oil-like finish, is Deks Olje. Deks is a unique product that applies like an oil but gets harder than an oil finish. It never builds to a high solids finish. Deks is a popular product to use on boat railings as it is easy to put on and easy to repair. Unlike cured varnish, Deks will adhere to itself without sanding. This is the characteristic that makes it so easy to use on railings. To renew the finish, all you have to do is wipe down the railing with a new coat.
 
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One more process often used by wooden boat builders / restorers is to epoxy encapsulate the wood prior to applying the finish.

The epoxy has to be a specialized, clear penetrating epoxy sealant such as Smith's Clear Penetrating Epoxy Sealant.

The sealant is water-thin and completely penetrates the wood leaving no surface residue. The sealant makes a very good base coat and any type of varnish or paint will adhere to it.

I have used it as a primer coat by mixing it with an alkyd oil paint in a 50:50 ratio for trim work on houses. It provides far superior performance when compared to a standard paint primer.

The only other penetrating epoxy sealant I would recommend is System Three S-1 Clear Penetrating Epoxy Sealer.

I have used the System Three S-1 as a base coat / sealer for Interlux Brightside one-part polyurethane paint. It is the only combination that has held up with no cracking, checking, fading, or visible deterioration under severe UV and weather conditions as the penetrating epoxy stabilized the wood, while the Interlux paint provided UV protection with a flexible coating that did not crack because of wood expansion / contraction from -5F to +100F.
 
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Another vote for Tru-Oil...

On the epoxy side, I've "learned" to like Brownell's Acra-Coat. I found it a bit tricky to apply at first (didn't appear to be going on evenly, when it was- and easy to spray too heavy/runs) but once I got over that hurdle I really came to like the stuff. Hard as nails.

Downside is that if you screw it up, you need to wait nearly a week for full cure to sand it off. No solvent will touch it, even uncured (at least, none that I know of including commonly used Acetone).
 
Buckhorn suggests thinning Waterlox, but I don't do that. A year or two ago I visited a distant family member that's a high level pro woodworker. He sells small side tables for $6000 each. The tables did look nice, but it was the finish that really impressed me. I thought maybe it was a professional secret, but he said it was Waterlox Original. He said to put down a primer coat first, and he used Watco Danish Oil for that. Then 4 coats of Waterlox should be all you need. I used it on my side tables, which I gave to relatives for free (or at a $6000 discount) and the tables looked great. I googled up use of Waterlox on gun stocks, and the reviews were all positive, so I tried it. Yup! Works great, though it has a long cure time. I apply it lightly with a small foam brush. Not so much that it runs. I use a hand light to check for runs. Coat 1 looks terrible. Coat 2 looks better, and later coats fill pores and flatten great. After a year or more on my 220 Swift stock, it still looks great.
 
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