Posted on July 7, 2024July 9, 2024 by Dale Phillips Questions: Gluing in India Questions: Gluing in India by Dale Zimmerman Originally published in American Lutherie #103, 2010 George Mathai from Kerala, India asks: My friend is a luthier based in the southern state of India, Kerala. For gluing the various parts and braces for his guitars and violins he uses Franklin Titebond glue and Behlen ground hide glue. However, in one of his custom-made flamenco guitars, a rattling sound brought the guitar back to the shop. One of the right fan braces had come off a bit and this was causing the rattling. For that guitar he had used the hide glue to glue the braces on. Kerala is well within the humid equatorial tropics and perhaps the humidity affected the gluing. What is the best glue that can be used to withstand high humidity? Dale Zimmerman from Franklin International in Columbus, Ohio responds: Hide glues such as our ready-to-use Titebond Liquid Hide Glue and most hot-pot hide glues are, and remain, quite sensitive to moisture. That affinity for moisture means that they tend to absorb water when exposed to high humidity or damp conditions, and that increase in moisture causes them to swell and weaken. Bonds that are not subject to stress may show little effect, as the glue loses that moisture and regains its strength as it returns to its original dry state. Where the bond is under stress, however, that stress is likely to cause some opening of the joint while the glue is softened. Ultimately then, the amount of change in a bond over time will be influenced by the concentration and duration of the moisture to which it is exposed and the stress, both inherent in the bond and that created as the wood involved changes in dimension in response to those changes in moisture content. That means that hide glues are generally considered a poor choice for bonds that are likely to be exposed to particularly humid conditions, especially those that are expected to be under meaningful stress. For such situations, yellow glues, which show little effect from dampness or elevated humidity are a decidedly better choice. ◆
Posted on July 1, 2024July 9, 2024 by Dale Phillips Questions: Liquid Hide and White Glue Questions: Liquid Hide and White Glue by Dale Zimmerman Originally published in American Lutherie #101, 2010 JM from the Internet asks: Both liquid hide glue and white glue are reviled by a lot of luthiers, but I suspect that a lot of highly regarded instruments were made using these glues, since these were widely used before yellow glue was invented. This makes me want to take a more objective look at these glues. Does anyone have a comprehensive comparison of the qualities of these glues and also of hot hide glue and yellow glue? Dale Zimmerman from Franklin International in Columbus, Ohio responds: As JM suggested, there are clearly differences between the various types of glue, and luthiers have learned to especially appreciate the characteristics of hot hide glue and yellow glue and feel less comfortable with liquid hide glue and white glue. With that in mind, it might be good to start with the fact that there is almost no difference in strength between the various categories of products. Become A Member to Continue Reading This Article This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page. If you are already a member, login for access or contact us to setup your account.
