My ‘Half-right Rule’ | Popular Woodworking Magazine

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Fine sanding. Finer grit sanding, such as in the lower half of this oak panel, which has been sanded to No. 600 instead of grain n. 180 in the upper half, does not close the pores of the wood as often claimed. Create finer scratches that hold fewer stains after removing excess.

Knowing which half to believe is why ending seems so difficult.

M.a few years ago I coined what I call my “half-right rule”. That is, half of what you read or hear about the finish is right; you just don’t know which half.

You might suspect he developed this rule in response to all the contradictory information published in woodworking journals, but I didn’t. The rule grew out of my experience with the elderly clerk, Glen, at the paint shop down the street from my shop, where I bought most of my supplies.

I’ve always enjoyed my trips to the paint shop because I was warmly welcomed and I knew I would learn something. Glen has worked with paints and finishes all his life and has given me many tips that have helped me improve the quality of my work. It also led me astray almost as often.

Of course, he wasn’t deliberately misleading me. He was simply relaying suggestions and explanations he had gleaned from painters and finishers he had come into contact with. Much nonsense is being passed on in these circles, and some of it has become deeply ingrained.

Here are some examples that might sound familiar.

Dilute the first coat of finish by half for a better bond. On the contrary, the full strength finishes adhere perfectly. The purpose of thinning is to create a thinner and easier to sand texture.

Don’t sand too fine or you’ll close the pores of the wood and it won’t stain. Do not “close” the pores with finer grits. You create finer scratches that hold fewer stains when you remove the excess.

Use sandpaper to soften the sharp edges as these will show wear too easily. The best reason to soften the edges with a couple of passes of sandpaper is because the finish is likely to peel off the sharp edges.

The longer you leave a wet stain on the wood, the more it absorbs and the darker the stain will be when you remove the excess. That’s not how it happens. The stain is not absorbing deeper; the diluent is evaporating, which leaves a higher dye / liquid ratio.

Note that in all of these examples the problem with education is not that you should or shouldn’t. It is the explanation of what will happen or why it happens or how it happens that is not correct.

When the “what”, “why” and “how” explanations are wrong, you find yourself struggling to understand the conclusion. Which side of the right half rule is correct?

My guilt

The stain becomes darker. I removed an oil stain within one minute (left) and after 30 minutes (right). After 30 minutes the stain is darker, not because it penetrates deeper, but because a lot of solvent has evaporated, leaving a higher dye-diluent ratio.

In addition to the nonsensical explanations, the fault lies also with incorrect labeling by manufacturers and inadequate instructions. Here, I have to take responsibility for the contradictions you have to work on. Take these examples.

Manufacturers typically tell you to apply the stain within two hours when using a wood conditioner to reduce stains. I’m telling you that you need to let the wood conditioner, if it’s oil or paint based, dry for at least six hours overnight to get good results.

Watco and other Danish oil manufacturers, which are blends of oil, paint and thinner, tell you to let the first coat soak in for 30 minutes, then apply a second coat and let it soak in 15 minutes. Finally, dry and the finish is ready to use in 8-10 hours. I (and others) tell you to let the first coat dry overnight after removing the excess. Then lightly sand, apply a second coat, wipe and let dry again overnight.

Manufacturers of virtually all brands of teak oil tell you that their finish provides UV resistance for outdoor use. I tell you this is not true. You need a construction (with the addition of UV absorbers) to effectively provide UV resistance, and there is no oil finish construction.

Wood conditioner. The instructions tell you to apply the stain within two hours of applying the wood conditioner. This does not reduce the stains. In fact, waiting two hours increases the stains because more thinner is evaporated. Here, I’ve applied the stain directly to the top section of this pine board. Then I applied the wood conditioner to the rest of the board and stain immediately, stain after 10 minutes, stain after two hours and stain the next day. After the wood conditioner has dried, the color is lighter, but there are no stains.

Again, you need to decide which side of the right half rule is correct.

Teak oils. The oils sold for teak storage do not work well, as evidenced by the fading in the lower half of this teak panel after less than two months of outdoor exposure. Excess teak oil must be removed, so there is no trace. For UV absorbers to be effective against sunlight, a top coat is required, as with many coats of marine paint.

What is the solution?

Tung oil. Clearly, the dried puddles of these two finishes are very different, but both are labeled “tung oil”. This labeling has caused great confusion for many years. The top finish is actually diluted paint (“cleaning paint”). It has nothing to do with tung oil (shown below).

Unfortunately, I don’t think there is an easy solution. Many people pass on information about finishes, including shop assistants and many who write about finish who have never done much of it. These people often lack the experience to contradict what they hear from others or read in literature.

I can tell you from my experience that it took me a long time to feel confident enough to contradict what I was feeling to actually say or write that was wrong. When everyone else says the same thing, the inclination is to think that your experience is lying to you in some way. Sometimes, I put something “out there” to see if I’ve had any pushbacks.

For example, I think every wood softener manufacturer says to apply the stain within two hours. It took me a decade to realize it didn’t work, because the wood kept staining when I followed the instructions, to finally realize that drying time was the explanation. My “washcoats” that used diluted paint worked well quickly because the paint dries much faster. Paint-based wood conditioner just takes a lot longer to dry.

It also took me a long time to contradict the prevailing claim that shellac is the best sealant. I finally had the nerve to say this can’t be true after learning that no large furniture store or furniture manufacturer uses shellac at all. (I should be careful to say “none” as there may be an exception somewhere.)

Perhaps the most difficult thing was understanding what tung oil was. Everyone knew there were differences. All kinds of attempts have been made to explain them: “resin reinforced”, “modified”, “machined”, etc. Finally, a chemist friend suggested I see what happens when I let puddles of various brands dry on the glass and tested the brands to see what they contained. Then it was clear. Many of the brands are not tung oil at all. They are paints diluted with paint thinner. They are just falsely labeled.

When the products are properly labeled with good instructions for using them and the what, why and how mythologies are clarified, the finish won’t be difficult at all. The half right rule will disappear.


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