The Difference a Film Makes
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!!
Recipe for Sanding Sealer? – Question of the Week
This week’s question comes from a viewer who writes: “I’ve really enjoyed your podcasts, they are all very informative. I recently found myself more exited about woodworking. Though I’ve had an interest since childhood, I never really had the resources, till now (my wife also supports my dream). Anyway, I was watching one of your podcasts and you mentioned a recipe for making your own sanding sealer. Would you mind repeating that on an e-mail, or even easier, remind me what episode I’ll find it. Thank you so much for the added inspiration, though I’m starting later in life than you (36, I know this is going to be a lifelong passion. Once again thanx Marc keep it up!!”
And this was my response:
“You just can’t underestimate the importance of spousal support in something like this. I know far too many people who have to work against the grain just to get a new tool. That doesn’t seem like much fun, lol.”
“As for a sanding sealer, I usually just use shellac. Typically a 1 lb cut. There are two ways to do this. I either buy pre-mixed shellac (Bullseye SealCoat), and dilute it from 2lb cut to 1lb cut. Or I simply but dry shellac flakes and mix my own using denatured alcohol. So its not a true sanding sealer by definition, but it accomplishes the same thing. Oh and just a word about true sanding sealers. In general, they contain material that can interfere with finish adhesion to a small extent. The stuff that makes it easy to sand is the same stuff that can weaken the bond of the finish to the surface. So in general, I stay away from commercial sanding sealers. Shellac on the other hand, provides a great base for just about any finish. Hope that helps.”
Danish Oil on top of Shellac? – Question of the Week
This week’s question comes from Eric in Canada who asks: “I know you like to use dewaxed shellac and transtint for a bit of colour, and finish it off with General Finishes. GF is extremely hard to find here in Canada. Dewaxed shellac and the transtint is pretty easy to get. I was wondering if I can use Danish oil on top of the shellac?”
And here was my response:
The only problem with Danish oil in this application is the fact that most Danish oil contains a high amount of oil. That oil will have difficulty curing on top of a pre-sealed surface (from the shellac). The General Finishes products are mostly varnish, if not all varnish (Arm-R-Seal). So what you are really looking for is a simple wipe-on varnish to put over top of the shellac. Minwax sells a decent one that is widely available. A few light coats should do the trick.
You might also consider using a different coloring agent. Even though I do occasionally use a dilute shellac/dye solution for coloring, its only for certain situations. In most cases, I do my staining with water-based dyes or gel stains. Neither of these really seals the surface and you should have no problem following up with a Danish oil if you use them. So really, the sky is the limit for your combinations of coloring agents and topcoats. But to directly answer your question, you want to avoid putting oil/varnish blends on top of sealed surfaces.
Spraying Oil Stains? – Question of the Week
This week’s question comes from Jorge who writes:
I’m finishing some maple kitchen doors. I have a Fuji Mini-Mite 3x to apply the finish. I first applied a 1.5 to 2 pound cut of shellac and now I’m spraying the oil based stain. The problem is that I get what I think is called orange peel. Basically I can see the stain dots in the doors. Definitely the stain is not applied uniformly. Here is what I’ve tried so far:
– Applied a thinner cut of shellac thinking perhaps the shellac was too thick. Initially I used a 2.5 to 3 pound cut.
– Sanded the shellac coat more aggressively using 220 grit.
– Adjusted the hell out of the gun. I adjusted the air pressure, fluid control, fan size and any combination of these three knobs with no success.
– I bought a #3 air cap thinking that the #4 was too big for the viscosity of the stain. No success here either.
– Thinned down the stain to 3 parts stain and 1 part solvent. This helped a little bit but still the result is not what it should be.
I’d appreciate any pointers you can give me because this thing is driving me crazy.
And this is my response:
Hey Jorge. Take a deep breath brother! I don’t think the problem is in the gun or your technique. Its in the materials. The shellac, even at 1.5-2lb cut, might be a little excessive in this case. Traditional oil-based stains rely on absorption into the wood to work properly. By sealing with 1.5-2 lb cut of shellac, you essentially created a barrier on the surface of the wood. So now the stain just pools, much like trying to use a marker on a glossy surface.
So here are a few recommendations. If you need to seal the wood first (which is not a bad idea for a blotch-prone wood like maple), just use a 1/2lb cut of dewaxed shellac. After it dries, sand it very lightly with 220 grit. This usually results in a surface that is only partially sealed and will still allow the some stain to absorb. So you can then spray on the oil stain, and wipe off the excess. Do not let it pool up. You may even skip the spray at this stage because all you really need to do is wipe the stain on. Now to be honest, I might even be a little hesitant to do this. I just don’t trust traditional oil stains over even partially-sealed surfaces. So for more predictable results, you may want to switch to a gel stain. The gel formulation does not rely so heavily on absorption and will give you a much better distribution and intensity of color, without any blotching. Once the stain dries, you can then apply the top coat.
Now going back to the shellac surface. Lets say you had that heavier coat on and you still wanted to add color. How would you do it? Well, you could always add some dye to the shellac itself. That’s a great way to bring some base color to the party. You could also add dye to lacquer (if lacquer is your top coat). I like to make very light dye mixtures (using both shellac and lacquer) that are mostly thinner and dye. But I like to add a little of the finish itself to the mix as that helps bind the dye to the surface. Basically, this is what is known as a “toner”. Hopefully that gives you enough to chew on. Good luck!
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