Home Forums Hunting & Shooting Gunsmithing Alternative to steel wool for "knocking back" Tru-Oil

You're right to be cautious on adding driers. Too much and the product polymerizes too quickly and cracking results. A quality commercial product should have about the optimum amount of drier. As Sitka is fond of saying, it's important that the product be fresh, including not sitting on the retailer's shelf for a year. I've gone as far as 50/50 with phenolic and tung or linseed with good results. But a quality commercial blended product worked about as well. I would expect the same from a blended polyurethane.

The very best gunstock finish I've ever used is Permalyn from Brownell's. I don't know what it is, but wish I'd known about it back when making furniture. And using 0000 steel wool has never caused any problems.

I have been uisng Minwax urethane spar varnish ,uncut for the first few coats until the pores are filled and then cut with 25-30% tung oil for many wipe on coats. Have not had had drying problems a tall.

If you want a pre mixed varnish and tungoil try Armorseal made by General. Strickly wipe on.

20 years ago you would have been correct about "long oil", "short", or "medium" oils, but those were all pre-polyurethane days. Before PU the finish properties were in large part determined by the oil, and were modified with additives like gums, resins, saturated oils, and waxes to give the finish more flexibility and lengthen the time before they'd crack. I've even seen old recipes with camphor in them. PUs revolutionized the finish world (don't want to get into the for better or worse argument). Now the finish properties are determined by the polyurethane. Today's "spar varnish" has about as much in common with historical spar varnish as today's "oil" finishes have. In fact, in many product lines the only difference between "spar varnish" and "oil" is the amount of solvent - less solvent = higher viscosity = "spar varnish", more solvent = lower viscosity = "oil". "Spar varnish" will also have some UV inhibitors in it, and can have silica in it as a matting and wear agent, that "oil" doesn't have, or has less of. An oil compatible PU is used in both "spar varnish" and "oil". The oil (BLO, tung, or a mix) in today's finishes is DIY aid - you don't need a good spray setup to use it. PUs have one trait that makes them not an optimal gun finish in PU/solvent form only, for the person not setup to spray. The trait is that solvent based PUs go down in defined layers (think mica and how you can peel it apart) because once a small amount of solvent evaporates from the current layer it is not soluble in the solvent, so subsequent layers don't blend into one single layer like a laquer will. If you spray, and are good, you can get subsequent coats on before it's too late, or use a catalysed PU and get layer blended to some extent. PU/oil gets around this as there's an oil layer between layers of PU that makes it more continous. Driers aren't that difficult to control, you just have to avoid the "more is better" state of mind. They are designed to be used sparringly. They are a cobalt salt in BLO, and if you use a lot it's the BLO in the drier that sets up a high stress film and causes cracking. Had a guy here, that thought he was the stuff after about 2 years of working with stocks, and he told me his "secret" to getting a good finish one day - he used bulk BLO mixed 50/50 with Japan drier for the last couple of coats. We had the drier discussion, but he wouldn't believe me; I don't think he's doing stocks anymore...

I've been using the Minwax also, and really like it!

Anyone thinking steel wool does not leave particles behind has not looked closely enough. Do the little freckles show without magnification? Not usually...

Steel wool was surpassed by orders of magnitude years ago...

Long oil versus short, and medium is still a legit way of talking about oil finishes. All it refers to is the cut and is important when considering the ease of working with the product in the typical shop. Long oil is simply that, long on oil. It will work easily and well.

As Saddlesore's post mentions "lengthening oil" in spar varnish, without using the terms it is probably a good idea to understand its origin.

In the old days short oil finishes were often used on the outside to protect the finish and build gloss...

Today's long oil finishes are not more flexible than short oil finishes. As kcnboise pointed out PU changed everything. Getting away from driers is both a bad idea and impossible. Driers do not usually go bad, but oil does every day. If your finish is not drying it is almost a guarantee the oil is old.

According to Flexner's book, copyright 2005, the difference between long and medium or short oil varnishes is the ratio of oil to resin used in the product. The type of oil or resin is not a factor. The spar varnishes have a higher ratio of oil, so are intended for outdoor use where seasonal moisture changes are greater. Marine products have UV absorbers added.

PU was developed in the 1930s.

I'm currently using a "wiping" varnish, Minwax Tung Oil Finish. I've been frustrated at the slow application and build. I poured some into a jar this evening and used a brush. What a difference! I should be able to finish filling the pores in short order.

To start I can name a dozen huge errors in Flexner's book... But he is exactly correct on the definition of "long oil" and that is exactly what I stated in my previous post. The "cut" is simply the amount of oil in the solution and a long cut means a lot of oil. Actually the type of resin is a huge factor, and oil almost no factor.

Spar varnishes do not neccessarily have more oil... though it is common for them to. Oil does not perform as well as most resins and using more oil in direct water exposure situations is not better... just the fact oil is far cheaper.

Lots of varnishes have UV inhibitors of several types, well beyond marine products.

PU was discovered and first marketed in the '20s IIRC, but it wasn't until the '80s that major changes hit the homeowner PU market and created the changes referenced. Waterbased PU was not perfected until the early to mid '90s so I would hesitate to claim it was developed in the '30s.

Minwax Tung Oil finish is an extremely long oil finish and would be one of my last choices for early filling coats on a stock. And once it is in there the oil will cure and shrink over months to years and telegraph the pores you worked so hard to fill.

I think it is a great finish after a short oil finish has been used to fill the pores. It top coats beautifully with the heavy application, dry 10-15 minutes, and then rub absolutely dry regimen.

As I understand it, the amount of oil to resin affects how flexible it remains after curing, and that is the only effect. Thus, the spar varnishes are long oil products for outdoor use because they will they will have the flexibility to move with wood that has high seasonal fluctuations in moisture content. The short oil varnishes are intended for indoor use, where they aren't subject to as much movement.

I don't exactly recall what Minwax Tung Oil Finish contains, but I'm pretty sure it's more than 60% mineral spirits. Once built up, it behaves like any other varnish, ie, dries hard and to a high gloss. When brushed, it builds well. That said, I won't use it for stock finishing anymore. My understanding is that the Behlen Rockhard varnish uses tung oil and phenolic resin, so it's hard without the drawbacks of PU. I'll mix in tung oil to get the sheen I want. Has anyone else done this?

SD, could you please point out the errors in Flexner's book? I'm curious, as I have not seen any, and on the whole it makes lots of sense. Thanks.

Paddler, you're still thinking about finishes from 20+ years ago. Like I, and Art, have said polyurethanes have changed the game. Spar varnishes can be long on oil, because they are short on solvent. "Oil" finishes can be short on oil, because they are mostly solvent. Evaporate the solvent out of both and the PU to oil ratio can be about the same. Today's finishes get their properties from the resin, not the oil. Some cheap spar varnishes are made the old way - you can tell them from modern finishes in that they take a long time to dry, feel rubbery to the touch for awhile, scratch more easily than modern finishes, and yellow more than modern finishes. In expensive "spar varnishes" they use a different kind of polyurethane than what's in "oil" finishes. It's a straight chain PU with higher molecular weight (meaning the chain is longer) than in cheaper PUs. The HMW straight chain gives it more flexibility and more resistance to the environment and wear.

On thing to be aware of with phenolics is that they yellow much more (and more quickly) than alkyd or urethanes. You can play around with coming up with your own brew, most guys have - me included, but it will quickly start to remind you of the Rolling Stones lyrics from "19th Nervous Breakdown" - "Your father's still perfecting ways of making sealing wax."

That is incorrect from my reading. The amount of solvent is immaterial, and affects workability only. Since the solvent, usually MS, evaporates, it does not affect the final finish characteristics, regardless of what the finish may be. It is the oil:resin ratio that determines whether it is a long or short (or medium) oil varnish.

My goal is to achieve a high luster but not gloss finish that holds up well. I'd prefer to avoid the PUs because they don't adhere as well to themselves or other finishes. Perhaps an alkyd varnish would be better, but the phenolic is harder and a bit darker. I am aware of the yellowing of the phenolic resins, so maybe an alkyd/tung oil blend would be best.

While PU has a large market share, other resins are still used in varnishes. My understanding is that if a varnish contains PU, it is most often on the label. Is that wrong?

Of course, all this would be mute if manufacturers told us what their products actually contain, wouldn't it? Why can't they just say this varnish contains 50% MS, 10% alkyd/phenolic/PU resin and 40% soybean/linseed/tung oil? What's so hard about that?

Your reading is misleading you is all I'm going to say... If you're interested in my credentials you can pm me; I've been in the industry.

Try reading for comprehension what I said about oil based PUs versus solvent based PUs. No interlayer adhesion problems with oil based PUs.

You can get any luster you want, because luster is determined by what you do after the finish is on and cured. You can use rottenstone and olive oil to get a high luster finish, rottenstone and mineral oil will give a high luster, but not quite the luster of olive oil (OO has a natural wax in it, it's what violin and other high end musical instrument makers use). Use 4f pumice and oil for a semigloss finish. Use 4f pumice and water for a matte finish.

Paddler
Some of your errors come from Flexner... Among the many things to look for are his descriptions of the differences between oils... There are precious few... Tests of cured tung oil show zero water resistance, exactly as much as linseed...

Look for descriptions of matting agents... and support for their use. I could go on and on...

Solvent content, both type and cut, is huge on finishes where water resistance matters.

Surface treatment is where the luster and matting should happen. Manufacturers need to keep their formulas secret to protect their marketing angle, though competitors need only analyze a sample to know what they use.
art

Thanks, Art. Flexner says that 5-6 coats of tung oil will yield a finish that is, "fairly water resistant", but goes on to say that it doesn't resist water vapor exchange very well. It's a moot point as neither tung or linseed is something I will use solo. Oils just don't do what I want in a finish.

Not sure what you mean by matting agents, please explain. He talks about flatting agents, which seem straightforward and is basically what I thought previously.

His description of long and short oil varnishes seems logical. I bought a quart of Behlen's Rockhard Table Top varnish today. The label says it's a "quality phenolic "short" oil varnish" intended for interior use. As I said above, I'll experiment with mixtures of it and pure tung oil to get the luster I want. Alternatively, I can use pure Varnish and rub it to the desired luster.

For the life of me, I cannot understand why you say that solvents, which evaporate, have any impact on the final characteristics of a film finish like varnish. Most people say that the solvent content only affects workability, or brushing ease, improve leveling and allow air bubbles to pop before the varnish skins over. After all, wiping varnishes are just regular varnishes containing more MS. Though they build slower, they still build, and water resistance is largely a matter of film thickness.

The big thing his book has done for me is to take the mystery out of finishing gunstocks. His explanations have debunked a lot of the incorrect statements I've read on internet forums. I'm finally understanding why things work and am getting the results I want. Even better, I know where I'm headed.

My biggest beef with the book is the fact he generalizes stuff and makes it look really simple... but the result leads in exactly the wrong direction.

In general, simplification of technical subjects takes serious skill to pull off... and the simpler it sounds the less likely it is to be correct. Maybe Heisenberg was correct... *

Solvents have to leave the finish before it can fully polymerize. Solvents, relative to the size of a water molecule are huge with limited capillary action. Any hole a solvent molecule can get through a dozen water molecules can run through holding hands. No solvents (as in pure oils) and there are no holes. Admittedly, the holes left by the solvent shrink a lot as the oil shrinks while polymerizing... but thinned finishes are demonstrably less water proof and that is and has been proven fact for a very long time.

Solvents are added for ease of application and do absolutely nothing positive for the final finish. A wiping finsh is supposed to be applied fairly heavily, allowed to soak in and then wiped absolutely dry. Working characteristics of the finish mean almost nothing with this process and it does a great job.

Water resistance is not a function of film thickness so much as layer porosity. A bunch of porous layers is not as good as a few intact layers. The defensible angle is that more layers of almost any finish is more waterproof than fewer... But that is elision at its worst.

I can say that because for a number of years I lab tested hundreds of finishes and different application systems thereof. I can say that because I saw how much weight samples gained when subjected to moisture. Only two finishes proved waterproof, good epoxy and cyanoacrylate.

Matting and flatting agents are essentially the same thing, silica added to the finish. Silica does not make the film stronger and it does not improve finish clarity. So if you like weakened muddy finish, get after it. Always use gloss finish and then use rottenstone or pumice to produce the desired surface luster.

I hate to say it, but gunstock finishing is not something I would try to find in Flexner...
art

*footnote from above on simplification... There is a tiny little book "Waves and Beaches" by Willard Bascom that is considered by many to be the finest example of a complex and technical subject delivered with amazing skill and facility. It is completely unrelated to wood finishing or guns in any way, but is worth the very brief time required to read and it will teach you stuff without effort. An amazing little book.

Good information Art. I always learn something when reading your posts. I came away from reading Flexner with a vague feeling of unease, now I know why.

In a real world scenario, how would you rate Epifanes Gloss spar varnish? Coming from the marine industry where, at least around here, Epi's is king, I have naturally gravitated to it for gunstock finishes. I use it over sealer coats of West System 207, as-is and rubbed out to final desired sheen after anywhere from 7 to 10 coats, or as a base for my "secret" (ha ha) "oil finish" formula. I have always been pleased with my results but wonder if I'm missing out on a something better.

Thanks,
Gary

Gary
Epiphane's is very good stuff... I am not sure you need the UV protection it gives in a stock finish... and using it over epoxy moots almost everything good about it. The epoxy does the sealing and the varnish is just needed for looks. It is easier to get oil looking good with minimal tooling. It also builds enough I would wonder what 7-10 coats would look like... How do you apply it?
art

Thanks again, Art. I think you're correct, that varnishes aren't waterproof, at least to the degree that epoxy or cyanoacrylate is waterproof. Not sure that last are, either, but that's unimportant. The important thing for gun stock finishing is that varnish is much more water resistant than the oils. And all varnishes contain large amounts of solvent, ie, MS. Most contain 50%, the wiping varnishes contain more like 60% plus. And, as you say, the solvent must evaporate before the much crosslinking occurs. So, I don't see a problem. If the solvents were a problem, it would be greater for varnishes with a higher percentage of solvent. It isn't clear to me that the wiping varnishes are inferior to regular varnish, however. Again, it's a moot point as I'll be using varnish and it's far superior to oil.

I understand about the flatting agents, what they are and what they do, and will not use them. I have a few Remington 700 Classics that started out semi-gloss that have become glossy with handling. As you say, the best way may be to "finish the finish" is to cut back on a high gloss to the luster one desires. The other way is to use a varnish/oil blend, as so many stock makers do. The Colorado School of Trades uses Velvit Oil, Pro Custom Oil, etc, Rich Cole uses Velvit Oil, some prefer Bematte, and so forth. I gather these are easy to use, fill grain well, etc.

For me personally, finishing a stock was a complicated mystery, made so because of misinformation and misleading labeling. It has become fairly easy now. After a thinned sealer coat on top of stained or unstained wood, all other coats are topcoats. If one wishes to fill the grain, one can do so with grain filler or the finish. If filling with the finish, you can use a brush on varnish the builds more quickly that a wipe on product. I started wiping on the Minwax stuff with my fingers, then a clean cotton cloth, then my fingers again. It took an incredibly long time, and it was nearly impossible to get an even coat. I'm now brushing it, and it's much faster and yields far superior results. Just make sure your brushing technique is good. So, all those who have done hand rubbed Tru Oil finishes take note, it doesn't have to be that hard. Just brush on a good varnish with enough coats to fill the grain, then sand it smooth, apply a final coat, then rub it out after it has cured. The only question that remains for me is how long to wait, as full cure takes a while. I've read one should wait a couple of months. I wonder if putting them into an even at 150F would speed things up.

Art,
I use badger bristle brushes. I hang the stock vertically and brush it on pretty thick, letting the varnish cascade down, and dodge the drips with a dry bush as they accumulate on the bottom edges until the varnish quits running and starts to skim over. If done quickly and with a heavy enough application, I don't get runs, waterfalls, or holidays in the finish- as a rule- and the varnish kind of settles itself into a thickness that it wants. The trick is to have the patience to stand there for a half hour or more dodging the excess that accumulates along the bottom edges. As long as one keeps that stuff dodged away, the film continues to self level and sags iron themselves out (within reason), I'm guessing through the surface tension of the film pulling the whole works down.

During the build coats if a waterfall does go undetected, I let it cure then block it with 320 and vigorously rub with mineral spirits, then let cure again, and final block it with 320 until it's level. Then block the entire coat and apply the next one.

We had a saying: "A marine finish is made of expensive materials meticulously applied and laboriously removed." That in reference to the tedious blocking between coats with 320 or 400 grit, which I feel is the real key to a successful finish.

I do like the added UV protection of Epi's. While it may not be wholly necessary on a gun stock, I like to think that my work may survive a century or more and I want to give it every advantage I can.

P.S. This is the same technique I use on split cane fly rods.

Nice, gnoahhh. I use a pretty standard technique with the product I'm using now. I brush it on as smoothly as possible, fairly thin coats, then "tip it off", going over sags and air bubbles with just the tip of the brush with the brush perpendicular to the surface. I wipe any excess off the brush on the edge of my jar. It probably builds slower than the way you do it, but it works well. Sometimes it comes out a bit thin, but using good light helps. I think my brush is Chinese hog bristle, chisel tipped. Seems to be of good quality.

Good tip about sanding, then curing sags. I've wondered how to deal with them. I have always just sanded them level and then allowed them to cure further. I'll try the MS.

Do you have a jig for holding your work? I'm doing shotgun stocks, and a jig would help a lot.

How many coats does it take you to fill the grain on average? Which varnish are you using?