Michael Dresdner

Q: Can I add dry pigment to lacquer to color it?
A: In theory, yes. In practice, it is almost impossible to get pigment powders to disperse uniformly in liquids. When we add them in the industry we use tools specifically designed for forcing pigments to combine with liquids, such as ball mills and high shear mixing blades. Unless you do some formulating on the side, you probably don’t own these machines, and you will find that trying to either stir most pigments into lacquer, or incorporate it with a drill bit mixer, will be an exercise in frustration. In addition to mixing tools, formulators often incorporate dispersal and suspension agents into the mix to keep the pigment from settling too quickly to the bottom of the container, and allowing it to remix easily. Odds are you don’t have access to those ingredients either.

Q: I have a lot of tubes of various oil paints on hand. Could I use oil paints as a pigment to add to lacquer?
A: If you are talking about concentrated oil colors in paste form in tubes, yes you can mix a small amount into lacquer, but don’t try to add too much. Even with just a bit, it will make the lacquer dry slower and set to a softer film; add too much and you will have a finish that takes forever to dry and is very soft indeed.

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Q: I am using McFadden nitrocellulose through a standard spray gun. I just successfully shot my first guitar and am working on another which I would like to tone with a dark opaque to light translucent wine red on the headstock veneer and carved maple top. I am having a hard time determining if I should color the wood before applying lacquer or if I should mix a pigment into the lacquer.
A: First, McFadden has gone out of business, but have no fear; Seagrave Coatings bought their formulas and intends to continue their fine line of guitar lacquers. I’ve spoken with the president of Seagrave and feel quite confident we will be as happy with them as we were with McFadden.
As for the toner, while either can be done, it is far easier to color between coats of clear finish than it is to color the raw wood. However, I would not add pigment to the lacquer; I would add dye. Use an oil soluble dye predissolved in solvent, or use a universal dye concentrate or NGR dye. Enough coats of dyed lacquer will indeed look opaque, so you can get the hiding characteristics you want at the very dark edges. In addition, you can maintain the translucency you need as the corona graduates to the lighter center.

Q: Where can I get information on custom color stain? We can’t find the color we want for an entertainment center. Can you teach us how to mix our own?
A: I can indeed, and in fact, have done so in all four of my books on finishing and many times in magazine articles. However, there is a much simpler alternative that may be just the ticket in this instance. Let someone else mix your custom stain for you. Here’s how.
Go to the paint or home store where you will find a myriad of paint chip samples on the display wall. Find the color paint that is the same as the color of stain you want, and have the clerk mix a small can of that color in low cost latex wall paint. Take it home and reduce it 100%, that is, half paint and half water, and you have made a custom color wiping stain. Flood it onto the wood and wipe off as much or as little as you want to get not only the color you want, but the density of stain color as well. This custom stain is easy to use, inexpensive, and is compatible under just about any clear finish you have chosen.

Q: I’ve been using cellulose sanding sealer on my woodturnings. What’s the difference between it and Zinsser SealCoat, and which is better? I normally use wipe on polyurethane as my finish.
A: Better is a personal judgment you must make, but I can certainly tell you the differences. Cellulose sanding sealer is lacquer laced with stearate, a soft soap that adds loft and thickness to the lacquer. It sands easily and tends to powder under sandpaper. However, some finishes, including many polyurethanes, can have adhesion or compatibility problems with stearated sealers. For that reason, I generally suggest SealCoat under such finishes. SealCoat is pure dewaxed shellac, and although it does not sand quite as easily as stearated sanding sealer, it is compatible under just about any finish, and offers more clarity as well.

Q: Any word on the Lawrence McFadden Seagrave deal?
A: The decision of the bankruptcy court that must approve Seagrave’s purchase of Lawrence McFadden has been postponed until February first. I will get back to you via this blog once that is finalized, but in the meantime, I spoke at some length to Peter Tepperman, the owner of Seagrave Coatings, this morning and he told me he has every intention of continuing to offer the McFadden formulas for instrument finishes, gel urethanes, and other standard line products for which McFadden has developed a fine reputation over the years. The conversation left me very confident that I can now recommend Seagrave Coatings with the same fervor and assurance as I always did with McFadden in the past. I think we have a winning situation. Here’s a link to Seagrave so you can see what they are all about.
www.seagravecoatings.com

Q: I sprayed a very thin final coat of lacquer on a guitar when it was cold and humid, and the finish blushed. I had to spray another coat of thicker lacquer and the blushing went away. I think I understand the reason why blushing forms, air trapped, but what I don’t understand is why thinner lacquer makes it worse.
A: Blushing is not caused by trapped air; it is caused by trapped water. When the relative humidity is high, no matter whether it is hot or cold, you can get blushing. Here’s how it happens.
High relative humidity means the air is holding almost all the moisture it can hold. As air gets colder it is less able to hold moisture. Thus, if the temperature were to drop just a few degrees, you might just hit the dew point; that point at which the air is overloaded, relative to its temperature, and moisture starts to come out of the air as condensation.
When you spray a very thin coat of lacquer, the abundance of thinner flashes off very quickly. This process of evaporation uses energy in the form of heat. Thus, it robs heat of the surface and the immediate surrounding air, making the air just above the evaporating solvent a bit cooler. Sometimes it is just enough to condense the water in that air, and that condensation gets trapped in the lacquer as blush.
It should be obvious now that the way to avoid blush, other than not spraying when the air is laden with moisture vapor, is to slow down the evaporation rate of the lacquer, and in fact, one of the most common blush eliminators is simply slower evaporating solvent. That way you can still spray as thin a coat as you like, but without the blush. Does that help?

Q: Can I put an oil based urethane on top of waterbased Varathane?
A: Yes. Varathane is polyurethane, and oil based urethane can go over waterbased, provided the waterbased is fully cured and all the water is out of it. Do bear in mind that one of the reasons for using waterbased polyurethane is that it goes on clear and does not yellow over time. Oil based goes on slightly amber and does yellow over time, so expect some color change if you switch to oil based in mid stream.

Q: I want to make jewelry out of glued twigs and have it be durable. I need to glue the shape together with PVA glue and then coat the entire piece with a sealer. I have read about cyanoacrylate and epoxy resin. Any advice?
A: There are a wealth of good sealers that will work for jewelry, including the two you named. The one warning I would issue has to do with both the sealers and the glue; make sure your twigs are dry before either gluing or finishing. There are glues that are more amenable to wet wood, but PVA is not one of them. Also, if bark is still on them, be certain the twigs were cut in winter or the bark is very likely to fall off in time.

Q: I’m having some problems getting dye to take evenly on soft maple.
A: I’m not surprised. Soft maple is notorious for growing with twisted and wavy fibers. That means when you cut a flat surface, you are actually getting flat grain interspersed with end grain. When you stain, whether with pigments or dyes, the end grain absorbs more stain and comes out darker.
When the pattern of the end grain is regular, we call it curly or quilted maple, both very common in soft maple, and talk about how the stain enhanced the figure. However, when it is random, the enhanced end grain is regarded as unattractive, and we call it blotching.
There are a number of ways to color wood to maximize grain patterns, and ways to minimize them as well. I’ve talked about both over the years on this website, and cover both in the coloring sections of all of my books.