The Difference a Film Makes

Article - November 12, 2009

Recently, I asked Guild members to help me select a finish for my new wall-hanging tool chest. We had the standard options including water-based poly, shellac, lacquer, oil-based poly, and oil & wax. Although water-based poly won with 27% of the votes, there was a very vocal minority (you know who you are lol) who wanted to see the oil & wax finish. So this resulted in a number of discussions about oil & wax and what kind of value this finish has to a woodworker. Personally, I am not a fan. An oil and wax finish is time-consuming to apply and offers very little in the way of protection. Yes its better than nothing, but just barely.

Now if you read just about any finishing book, you’ll come across one of those handy charts that compares the key properties of different finishes (usually abrasion, heat, and moisture resistance). These charts can be incredibly helpful, but nothing is more eye opening than a simple, practical, home-brewed test! Am I crazy for disliking the oil & wax finish??? To answer that question, I decided to make up a few sample boards and run a little experiment of my own.

I took 4 scrap pieces of baltic birch plywood and finished each one with different materials. My assumption is that if you are considering oil & wax as a finish, you are probably a fan of that “close to the wood” look. So the film finishes were applied very lightly in an effort to keep everything consistent. Here’s how I treated the samples:

BLO (boiled linseed oil) Only – I sanded the board to 320 (for oils, I like to go a little higher than usual to help promote even absorption). I flooded the board with BLO and let it soak in for an hour. I then wiped off the excess with a clean cotton rag and let the board dry in the warm Arizona air for the entire day and overnight. The next day, I repeated the application process. I did this for a total of three applications.

BLO/Wax – I treated this board exactly as above, only after waiting about 4 days after the final oil application, I applied two coats of paste wax and buffed it to a very pleasant sheen.

BLO/Shellac – I gave this board the same BLO treatment, but instead of wax after 4 days, I gave it two coats of Bullseye SealCoat (2lb cut).

Varnish Only – Sanded to 180. This board received three light coats of Arm-R-Seal satin with sanding in between.

When it was all said and done, each board (with the exception of the BLO-only), had a nice, natural-looking satin appearance. The BLO-only board was dull, as one would expect.

So now for my not-so-scientific test. I wanted to simulate a spill of some kind. In this case, I used a fairly concentrated solution of Transtint Dark Mission Brown in water. I placed a quarter-sized puddle of dye on each board, and let it soak. Let’s pretend this is soda, coffee, wine, or maybe even some delicious hot cocoa (we ARE entering the holiday season you know). After 5 minutes, I wiped away the excess dye and then scrubbed the surface with a damp rag. Here are the results:

The BLO-only sample looks………well……it looks like a bird took a poo on it. The dye seeped into the grain and through capillary action, traveled well beyond the original location of the dye. A stain like this would be very difficult to repair. And if the project is made from plywood, you’ll most likely burn through the veneer before you completely clean up that stain.

The BLO/wax board clearly fared better. The wax does a decent job of preventing complete absorption of the dye and the spread was fairly limited when compared to the BLO-only board.

The BLO/shellac proved to be reasonably protective. A small amount of staining is present but it doesn’t seem like the dye penetrated far enough to travel through the grain. The staining is generally limited to the shellac film, and never really touches the wood. This would be a very easy repair.

And finally, we have the varnished board. Boring right? Honestly, there just isn’t anything to look at. The varnish completely blocked the dye from absorbing into the wood fibers.

Really there was nothing surprising here. Film finishes simply protect the wood better than non-film finishes. But deciding what finish to use on your next project depends on a number of factors, and protection from spills is only one of them. So try to pick the finish that suits the project at hand as well as your personal tastes.

What is my take on this? Personally, I am a big fan of the wiping varnish finish. Just take a look at my DVD, *wink wink*. You can apply just a coat or two to get that close to the wood look and feel, or you can slap on six or seven coats for the ultimate in protection. If you like the deep amber hue that BLO brings to the party, why not start with a single coat of BLO, and finish by top-coating with your favorite varnish? Or maybe compromise and use a Danish Oil or even a home-brewed oil/varnish blend. But when it comes to my projects, the time it takes to produce a BLO finish, coupled with the overall lack of protection, puts it smack dab at the bottom of my preferred finishes list.

Now one other thing that I must mention is repairability. Unfortunately, varnishes are not as easy to repair as other finishes. Shellac, lacquer, and BLO can all be sanded down and re-coated with excellent results. But with varnish, sanding too much can result in witness lines if you burn through one layer and expose the one beneath. So if you are repairing a varnished surface, you really have to take it easy. Fortunately, the increased durability of a varnished surface means you are a lot less likely to damage it.

So like many things in woodworking, its a balance and a compromise. But ultimately, its your project and your shop, and you are the boss. So choose whatever finish tickles your fancy. But if you want a truly durable surface, you should definitely give a film finish strong consideration. And of course, clean spills quickly and encourage the use of coasters!!