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What Is A Woodworker To Do
What Is A Woodworker To Do
Created by Steve on 8/29/2010 5:24:32 PM

Finish manufacturers label products to sell finish, not to impart accurate information to the consumer...

What is a Woodworker to Do?

What is a woodworker to do when a so-called “Oil Finish” is not an oil finish, and when a finish marketed as “Varnish” or “Lacquer” is neither varnish nor lacquer?  We are going to change directions a bit in the next few issue of this newsletter and devote the Back Page Article to exposing examples of misleading and deceptive advertising in the world of finishes—unfortunately there are many examples from which to choose.  Because misleading advertising is so common, far too often we are sold something that is not what the product name would lead us to believe we are buying.  Most of the time this deception will not cause a major problem for our finish;  but, there are times when we have a specific need for a particular type of finish and we buy the wrong product, thinking we are buying something else.  It is at these times that deceptive labeling is, at the very least, annoying and at worst may result in an inferior finish or even finish failure.  This article, then, is devoted to helping you separate reality from marketing hype, and to select the finish that is appropriate for your need regardless of what the manufacturer has printed on the label.

I will begin this series with an examination of “oil finishes” in general and so-called “Tung Oil Finishes” in specific.  There are only two drying oils regularly used to finish wood; boiled linseed oil and tung oil.  The term “drying oil” means that these oils, when exposed to oxygen, will “cure” to form a finish film.  Oil finishes are characterized as being 100% solids—there are no solvents or thinners (volatiles) to evaporate during the curing process.  All of the oil that we apply to the wood will polymerize during the curing process to form the finish film. Understanding this property of oil finishes is our first clue in determining whether a finish that is advertised as being an “oil finish” really is. If the label states that the can contains “petroleum distillates” or thinner of any kind, it most definitely is not an oil finish. Pure boiled linseed oil and tung oil are never thinned. So, we know immediately that the so-called “Oil Finishes”, whether "Tung Oil Finish", "Antique Oil Finish", "Danish Oil", or any other " fill-in-the-blank Oil Finish" are not “oil finishes”—all such pretenders list petroleum distillates or thinners in their ingredients.

So, if these finishes are not oil finishes, what are they? Minwax, Behr, McCloskey, Formby’s, Zar, and a host of other manufacturers make “Tung Oil Finish”. Most of them contain absolutely no tung oil, and of those that do contain tung oil, the actual volume of the stuff is so minimal it is irrelevant. So, why do these manufacturers call these finishes “Tung Oil” when there is no tung oil in the can? Simple! Because inclusion of the magic words “Tung Oil”, beginning with the introduction of Formby’s Tung Oil finish back in the 50’s, has been shown to stimulate the sale of these products, demonstrating conclusively that the important thing, to far too many consumers, is not what is in the can, but what is printed on the can.

OK, so there is no tung oil in these finishes—and they really are not “oil finishes”, then what are they? Well, it depends on the manufacturer. Minwax and Behr Tung Oil Finishes, two of the more popular brands, are actually what we call oil/varnish blends (a.k.a. “Danish Oil”). Oil/varnish blends are simply more or less equal parts varnish, boiled linseed oil, and mineral spirits. (Now you know why we don’t tie up valuable shelf space with “Danish Oil”—you can make your own for less money.) Neither of these products contain so much as a drop of tung oil. “Tung Oil” appears only on the label.

On the other hand, Formby’s, Zar, Gillespie, and Hope’s “Tung Oil Finish” are wiping varnish—nothing more than regular varnish to which mineral spirits has been added, thinning the varnish so that it can be wiped on. (You can make your own wiping varnish by thinning the varnish you already own 50/50 with mineral spirits.) As with the oil/varnish blends mentioned, none of these wiping varnishes contains so much as a drop of tung oil.

Is there anything wrong with “Danish Oil” or wiping varnish?  Of course not, just understand what you are buying and be sure that it is what you want.   If you don’t mind being lied to, these finishes perform just as well as any similar finish that is accurately labeled.

But, sometimes deceptive labeling creates a problem. To illustrate, in the December, 2005 issue of Fine Woodworking, Lonnie Bird, an incredibly accomplished woodworker, concluded a series of articles on building a curly maple secretary. In his final installment he applied the finish, which he describes as water-soluble dye followed by oil and topped with shellac. This is a finish schedule that I whole wholeheartedly endorse. Unfortunately, it is not the finish Mr. Bird actually applied. Here, in part, is what he had to say:

“(After the dye is dry) I flood the surface with an oil finish such as Waterlox or Formby's Tung oil, making sure to cover all the crevices and details. After a few minutes, wipe away the excess. Let the finish cure overnight (and then apply the shellac)”.

If Formby’s or Waterlox were “oil”, specifically tung oil, this finish schedule would make sense and the application method Mr. Bird used would be appropriate. Unfortunately, neither of these finishes is actually "oil" nor are either of them tung oil. Formby’s Tung Oil Finish is an alkyd resin wiping varnish made with soya (soybean) oil. It contains absolutely no tung oil. Waterlox Sealer/Finish, on the other hand, is a phenolic resin wiping varnish made from tung oil. (Please note that Waterlox makes no claim that their Sealer/Finish is “tung oil”. The label clearly states that it is a finish made from tung oil.) Being made from an oil and actually being that oil are two completely different things. In a future article, when we examine varnish, I will explain that distinction.

The bottom line is that the finish actually applied by Lonnie consists of water-soluble dye “sealed” with a coat of improperly applied wiping varnish, and then topped with shellac. This schedule makes absolutely no sense! Why on earth would one apply shellac over varnish? Clearly, Mr. Bird has been led to believe that Formby’s Tung Oil Finish and Waterlox Sealer/Finish are oil finishes, specifically tung oil. There can be no other explanation for this curious finish schedule.

If Lonnie Bird can be swayed by deceptive advertising then all of us are at risk.  Our only hope is to learn to recognize the clues and not to rely on the truthfulness of labels.  Here is a simple test that you can conduct in your shop to confirm the accuracy of a manufacturer's label.  This test that will conclusively identify the the nature of a oil or oil-based finish; is it actually oil, or is it an oil/varnish blend or simply oil-based varnish masquerading as oil?

Begin by applying a few drops of the finish to a pane of glass laid flat on your bench. Wait 6 to 8 hours and observe how it has “cured”.

  • If the finish is easily wiped from the glass it is oil.

  • If the finish is “cured” but has a wrinkled appearance, particularly around the edge, it is an oil/varnish blend.

  • If the finish is hard and smooth, it is varnish.

We do not play the label game at Hardwood Lumber & More....  To that end we do everything we can to make sure that you understand what you are buying.  If you have questions please ask...