The Ultimate Finish Question?

[Dennis Collins]

First I admit that I am a novice when it come to finishes so my confusion is somewhat based on the lack of education and experience. I often here about BLO, Tung Oil, Danish Oil, Linseed Oil. Teak Oil, Shellac (waxed and dewaxed), Varnish, Laquer, Urethane, Polyurthane, Wipe on (whatever), and Waxes as finishes.

My understanding is that most all finishes (except pure oils 100% BLO, Tung, etc) are varnish based or the comtemporary name: urethane resins. Although it is hard to find something called just "Varnish". Most are called Polyurethane, Urethane, Wipe on Finish and Antique Oil or Tung Oil finish (not 100% pure oil). Is this correct that they are all varnish based? If so, what is the difference?

Here are some examples of name brand finishes that are common off the shelf items either in borg or woodworking speciality stores. What are they in regards to the type of finish i.e. varnished based urethanes? If you read the label, it really does not tell you anything specific or it gives you similar items on the MSDS for the same chemical (urethane resins).

Watco
Sam Maloof
Waterlox
Tried & True
General Finishes
Zinsser
Behlen
Minwax Poly Wipe On

or the 100% pure oils:
Tung
BLO
Teak

So my primary question is: So what is the difference if most finishes are varnish (urethane resin) based? I have disregarded the water vs OIL/VOC based finishes.

My simple answer is: They are essentially all the same, it is the user preference. i.e. Chevy/GMC debate

[Jesse Cloud]

Finishing choices can be incredibly complicated. I would suggest you look at this write up by Jeff Jewitt:

http://www.homesteadfinishing.com/htdocs/ChoosingFinish.htm

Any finishing choice involves a lot of variables - ease of application, potential for screw up, resistance to heat, moisture, abrasion, etc., light/dark, grain popping potential, and so on and so on.

[Jim O'Dell]

Jesse, that looks like an excellent article. I've copied it into my computer for later reading. Can't take the time now. Working with SWMBO doing Christmas....er Holiday Cards. :o We're running just a little bit late again this year. :D

Good question, Dennis...Thanks! Jim.

[Jim Becker]

My understanding is that most all finishes (except pure oils 100% BLO, Tung, etc) are varnish based or the comtemporary name: urethane resins.

Far from it. All oil-based varnishes do have BLO (boiled linseed oil), tung oil or sometimes soya oil as a base component, but the resin used as a base component might be alkyd, phenolic or polyurethane. It just so happens that most retail shelves are stocked with polyurethane varnishes...and the marketing would have you think that they are the best thing since bacon and eggs. Not so. Polyurethane based varnishes were primarily intended for floor finishing as the primary "feature" is abrasion resistance. (Which also makes them slightly softer than the other two types of varnish. For furniture, there is much less benefit in using this kind of finish, despite the hype, and alkyd (example: Pratt & Lambert #38 which is also soya oil based) or phenolic (example: Waterlox) varnishes have much more clarity and provide a harder finish...nice if you want to rub it out. All varnishes, no matter what the original ingredients are basically "cooked" together to form a completely different substance that provides the characteristics of that particular finishing product.

Lacquer has nothing to do with "varnish"...it's a completely different kind of finish. It's derived from a tree or other cellulose sources Same for Shellac--not a varnish...which is basically a bug secretion. (really)

And when you get into water borne finishes...you're talking about acrylics or sometimes a solvent or oil based product emulsified into a water carrier for easy application and lower VOC (volatile organic compounds).

The bottom line...they are not all the same. Watco and most other products labeled as "danish oil" are oil/varnish blends. Minwax Wipe-On Poly is a thinned (with mineral spirits or similar) polyurethane based varnish. Shellac is dissolved in and cut with alcohol...no oil involved. Lacquer is cut with very volatile solvents...again, no "oil".

While the choice is very much a personal choice, there are generally good reasons to use one finish or another...or a combination in a finishing regimen that works for a given species and/or project.

[Howard Acheson]

I would strongly suggest you get Flexner's Understand Wood Finishing from Amazon. It will answer all your questions about finishes and finishing.

To answer a couple of your questions.

BLO (Boiled Linseed Oil) is linseed oil that has had some chemical driers added to cause it to cure more rapidly.

Varnish is a finish made by mixing and heating a resin and a drying or semi-drying oil. At a certain temperature the two components combine to form a new chemical called varnish. The most often used resins are alkyd, phenolic and urethane. The oils are linseed oil, tung oil and soya oil. Each of the resins and each of the oils makes for a different characteristics of the resulting varnish. Some resin is lighter in color and some oils are lighter in color. The amount of resin and oil is varied to make the resulting varnish harder or softer.

Poly or Polyurethane is a varnish made from urethane resin.

Products labeled "Danish Oils" and "Tung Oil Finishes" are marketing names for what are generically known as oil/varnish mixtures. As the name implies, these products are just varnish, boiled linseed oil and a thinner. They are not really oils.

Wiping varnishes are just standard varnish that has been highly thinned so it can be applied with a rag or non-embossed paper towel.

"Teak Oil" is just another name for an oil/varnish mixture that is marketed to the boating industry.

Waterlox and Behlen are brand name of a companies that make families of oil based varnish products. There are other manufacturers like General Finishes, Minwax, Pratt & Lambert, etc. It's not the name of any specific finish.

Zinsser is the name of a company that makes shellac which is a finish made from the secretions of the lac bug that is mixed with alcohol.

[Dennis Collins]

Thanks to everyone for your replies. I will definitely get the book suggested and see if I can educate myself on the various mixtures that make a varnish/poly finish. And most importantly, the proper use for each finish.

By the way, I did know that Shellac came from bugs. Now, who in the world though about using bug residual as a finish???

[Jim Becker]

By the way, I did know that Shellac came from bugs. Now, who in the world though about using bug residual as a finish???

What's more, it's used as a coating on some candy and medications... :D

[Al Wasser]

Fine Woodworking has had some good finishing articles in the last 3-4 issues. If you have a library handy you might see if you get those and perhaps copy some of them. Perhaps other mags. also may good finishing articles. Might even check out a book or two on finishing.

[Howard Acheson]

>> who in the world though about using bug residual as a finish???

The Chinese and the Indians (from India)

[Jim O'Dell]

What's more, it's used as a coating on some candy and medications... :D

If you're going to tell me M&M's have this so they don't melt in my hand, I might have to come hurt you! :D:D Jim.