Posted on January 19, 2010September 10, 2025 by Dale Phillips Questions: Finish For Cocobolo Questions: Finish For Cocobolo by John McCarthy Originally published in American Lutherie #78, 2004 and Big Red Book of American Lutherie Volume Seven, 2015 Paul Dernbach of Naples, Florida asks: What is the best way to finish cocobolo? The varnish I tried on it isn’t dry after three weeks. It dried fine on my purpleheart sample. John McCarthy of Murfreesboro, Tennessee responds: The oils in cocobolo rarely dry well enough to use a gum-based varnish. I have had success with French polish (shellac) as a method for sealing prior to using any other finish. Shellac is unaffected by the oils in cocobolo. Build a thin layer of finish that doesn’t add much to the final coats. If you want to continue with the French polish, you will get good results and a very well-developed muscular arm at the same time. I tend to use shellac to seal then apply nitrocellulose lacquer over it. I like the results of French polish, but it is very time consuming and a bit difficult to match and repair if using other than as a base. I like the ease of a good nitrocellulose with a plasticizer which reduces the tendency of the finish to crack. I use an HVLP system to minimize overspray. I prefer Mohawk stringed instrument lacquer.
Posted on January 19, 2010September 9, 2025 by Dale Phillips Questions: Spalted Maple Mold Questions: Spalted Maple Mold by Bob Woodcock Originally published in American Lutherie #69, 2002 and Big Red Book of American Lutherie Volume Six, 2013 Mike Collins of Argyle, New York asks: I just came across some nice spalted maple and made a rosette of it. After I was done, a violin maker told me that you could die from the mold in the wood. Where can I get more information about this? A few days later, Mike wrote back with this information: I found a website, www.woodbox.com/data/wood/ that has some information on spalted wood and possible health problems. Here’s an excerpt: “Spalted wood may still contain spores, therefore it should always be worked and sanded only when wearing a good dust mask or respirator, and using a dust collector. There is medical evidence that substances from decaying wood are a health threat, and some allergic reactions and serious lung diseases have been traced to spores and fungi that inhabit rotting wood. The effect on an individual woodworker however depends on his/her natural tolerance to the spores and fungi, since some individuals are more likely to react to environmental toxins than others.” Become A Member to Continue Reading This Article This article is part of the Articles Online featured on our website for Guild members. To view this and other web articles, join the Guild of American Luthiers. For details, visit the membership page. MEMBERS: login for access or contact us to setup your account.
Posted on January 19, 2010September 9, 2025 by Dale Phillips Questions: Spalted Wood Toxicity Questions: Spalted Wood Toxicity by Bob Woodcock Originally published in American Lutherie #71, 2002 and Big Red Book of American Lutherie Volume Six, 2013 Bob Woodcock of Conshohocken, Pennsylvania responds. Bob is both a poison information specialist and registered nurse. As to the question about spalted maple being lethal, the writer may be referring to my Dec. 1991 article on wood toxicity in Wood magazine. I mentioned a case of a wood turner with allergic asthma who was found dead in his shop with spalted maple turning on the lathe. The cause of death was acute asthma. Spalting is mostly a result of Cryptostroma corticale, a potent allergy-causing mold. You’d know if you were allergic to it; you would sneeze, cough, or tear up while working with it. These allergies tend to get worse over time, and a period away from the substance will allow the body to increase its sensitivity. Workers with allergies from work exposure find that the first day back after a few days off are the worst. This is referred to as “Monday morning asthma.” Such was probably the case with the turner. After a weekend off, his immune system was primed and ready to go; exposure resulted in death. The take-home lesson is to use common sense. If the wood seems to bother you in any way, avoid it. ◆
Posted on January 19, 2010September 11, 2025 by Dale Phillips Questions: Choosing Top Wood Questions: Choosing Top Wood by John Calkin Originally published in American Lutherie #84, 2005 and Big Red Book of American Lutherie Volume Seven, 2015 Jerry Tekell of Italy, Texas asks: As a person somewhat new to instrument building I’d like to ask: Why do most builders use spruce or pine for guitar and mandolin tops? Why not maple, for example? I’d love to use maple on the top as well as the back of my mandolins, but I wonder how it would sound. John Calkin, GAL Contributing Editor, responds: Softwoods (conifers) are traditional for instrument tops, which also makes them what customers expect to see. Don’t neglect the importance of this. There are real-world reasons, though, as well. A wood needs to be strong enough to withstand the forces of string tension and compression (if you are talking about an archtop mandolin) and also light enough to be set in motion effectively by string vibration. Quartersawn softwoods seem to fit the bill better than the wood from deciduous trees. I tend to think of softwoods as fluffy, since they have a lot of air trapped in their structures. Hardwoods like hard maple are more like a metal (in my mind, not in reality) since they are very dense. Become A Member to Continue Reading This Article This article is part of the Articles Online featured on our website for Guild members. To view this and other web articles, join the Guild of American Luthiers. For details, visit the membership page. MEMBERS: login for access or contact us to setup your account.
Posted on January 19, 2010September 10, 2025 by Dale Phillips Questions: Guitar Top Grain Orientation Questions: Guitar Top Grain Orientation by Alain Bieber Originally published in American Lutherie #83, 2005 and Big Red Book of American Lutherie Volume Seven, 2015 Alain Bieber from Paris, France asks: Did a serious luthier of the past ever consider building with any other option than a strict classical “longitudinal” spruce grain orientation? A French patent of 1829 by a luthier named Lacoux is about a “guitare perfectionnée” whose main point is to have an “harp like” orientation of the soundboard, tilted 90° from the classical one. I never have seen that oddity, but Joël Dugot at the Musée de la musique (Paris) told me he thinks he saw it. Such old patents are stored in an old attic.
