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Oil vs. Film, Choose Your Finish

When it's time to apply a knockout finish, there are a lot of contenders. Some can take a punch; some bounce back fast. Here's how to choose the one that's a fair match for your project.

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Introduction

Introduction

For many woodworkers, the contest to choose a finish ends in round one. Whether it's polyurethane, Danish oil, or spray lacquer, the winner never changes. But the finish you like best may not be the best one for your project, depending on its style and use.

All types of finishes have strengths and weaknesses, and a strength in one situation may become a weakness in another. For example, do you want a finish that's thin enough to apply fast and easily, or one that builds a thick, protective film in just a couple of coats? Should it be water- and chemicalresistant or easy to repair? Do you want a surface you can rub out to an even sheen or one that resists abrasion?

Clear finishes fall into six categories, each with its own mix of characteristics.


Meet the six contenders

Drying oils, including boiled linseed oil and pure tung oil, penetrate the wood surface and react with oxygen to cure. Boiled linseed oil contains drying agents that let it cure overnight, but tung oil can take several days. Tung oil, however, darkens less with time. Beware: Some finishes with "tung oil" in their name contain little or no real tung oil as an ingredient.

Oil/varnish mixes, such as Danish oil, enhance grain while laying down a thin film. Because of their oil content, oil/ varnish mixes also need to dry overnight.

Lacquer combines nitrocellulose solids in a mixture of solvents to create a film finish that dries quickly and adds a faint amber tint. For a clearer finish, use cellulose acetate butyrate (CAB) lacquer. Unless you buy a formula that dries slowly enough to brush on, plan to spray most lacquers.

Water-based finish goes by many names that may include the words "lacquer" or "polyurethane," but most use acrylic or acrylic/polyurethane resins in solvent and water. By eliminating oil, and using acrylic and other clear resins, water-based finishes don't yellow as they age.

Wiping varnish, usually a type of polyurethane, comes premixed, but you can make your own by thinning regular varnish with mineral spirits.

Polyurethane varnish mixes alkyd and polyurethane resins with different types of drying oils. Unlike an oil/varnish blend, however, the ingredients are heated until they combine. Reducing the ratio of oil to resin creates a hard finish for indoor use. Increasing the amount of oil makes the finish flexible enough to withstand wood movement outdoors.

Now that you know the players, learn how to get the most from them.


The durability dilemma

On the following pages, we arranged these finish types with durability increasing from beginning to end. As durability increases, though, ease of repairs decreases. For example, lacquer offers little resistance to alcohol or water, but it's as easy to repair as spraying on a fresh coat. Polyurethane varnish ranks tops in moisture and chemical resistance, but repairing deep scratches requires stripping the old finish.


Continued on page 2:  Drying oils

 

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Comments (9)
7921667326
PeteM wrote:

The hypertext in these articles don't do what a reader would expect.

11/26/2013 08:56:40 AM Report Abuse
3-j wrote:

Wetting and sanding off the "nibs" is not logical. The water-based product will simply create "nibs" again. Just save yourself needless effort and skip the non-nonsensical wetting/sanding step and apply the finish. When you sand after that process, you will see no "nibs."

11/7/2013 09:39:45 AM Report Abuse
d.d.kelly.bodhi wrote:

So. When can we get our grubbies on your tome on shellac?

8/1/2013 04:00:32 PM Report Abuse
dhellew21 wrote:

You also missed Tung oil (non-toxic) and Teak Oil. Mix these two together for Tung penetration, Teak durability, and you have a durable, easily repairable finish. Great for kitchen and bath cabinets including counter top trim behind and in front with porcelain tile tops. Holds up to the abuse of rental houses where a light coat make it like new. The blend is durable enough for outdoor use, best light re-coated annually like most finishes. Thanks to the Feds it is only imported, made in Canada.

11/11/2011 09:59:22 AM Report Abuse
mjmnswartz@gmail.com wrote:

For best adhesion you should lightly sand polyurethane between coats. Sanding also removes the dust nibs that may be on the previous coat.

4/15/2010 12:57:21 PM Report Abuse
geezerpa wrote:

What about PENOFIN oil, I find it exceptional. I believe its a california company. Does not raise the grain, so no sanding.

4/15/2010 12:38:02 PM Report Abuse
joecal wrote:

Anybody have any advice/thoughts on a product I receintly heard about - Australian Tree Oil?

4/15/2010 10:25:58 AM Report Abuse
jsmythe3325231 wrote:

Hi Great article and well written. Could you do an addendum for Shellac. Thanks

3/12/2010 01:12:19 PM Report Abuse
Mr. Frodo wrote:

I liked this article but I don't see how shellac could be left out of an article on finishing comparisons

3/11/2010 11:35:00 AM Report Abuse

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