Gluing Up Thick Turning Stock

      Cracks may open up at glue bonds in large glued-up pieces, particularly in outdoor exposures. Here are some ideas for high-performance adhesives that may help. October 20, 2005

I sometimes have problems when gluing up 24/4 or thicker stock for turning squares. While all the joints may appear to be tight when the work is clamped, some of the glue lines open up later. It appears that the moisture from the glue is expanding the glue side of the outer layers, creating stress in the form of cupping that opens the joints. I learned the hard way that Titebond II is not structurally rated when I had problems with square turned porch posts and staved porch columns with glue lines opening up days or even months after turning and installation.

I've used structural epoxy to get around this problem but this is rather expensive. I have heard for years that you can starve a glue joint by using an insufficient amount of glue but I wonder if putting too much glue on would cause the theoretical wetting/tension problem. I am looking for advice on a cost effective adhesive for gluing up thick turning stock. I have also noticed that the harder woods prove more challenging to glue up into stable stock.

Forum Responses
(Adhesives Forum)
From contributor A:
I have noticed over the years that fat solid turnings do not age well in interior environments, and ditto/double for exterior work. The unavoidable humidity cycling will eventually cause cracks to open up in the wood, if not glue lines. The mechanism is shrinkage, similar to the way a whole log cracks as it dries. A 24/4 chunk works out to about 6", and I would question the MC starting out. If it is high for your area, then no glue will hold it. I try to hold solid exterior to 4" or less and hollow above that. Interior can be up to 6" solid, and hollow over 6". I use epoxy or resorcinol glue for exterior. I'd rather stay on the safe side.

From contributor B:
Have you tried polyurethane construction adhesive that comes in a caulking tube, such as PL Premium? I have been using it for years with excellent long term results. It doesn't grab like regular wood glue and takes longer to cure, about 3 hours minimum. It is a rigid plastic when cured and sands well. When sanded it also matches wood and stains well. It is also 100% waterproof.

From the original questioner:
I have used PL but mostly for repairing old columns with the idea that its gap filling qualities are beneficial and it is easy to trim the squeeze-out flush after it has cured. I have mixed success because of the varying conditions of the wood surface. I have never tried it on new clean wood but I may on some future paint grade project.

From Gene Wengert, forum technical advisor, Sawing and Drying Forum:
A hot-melt PUR would be ideal. You get good gap fill and high strength. The PUR (PolyUrethane Reactive) adhesive is a 100 percent solid, one-component urethane prepolymer that behaves like a standard hot melt until it reacts with moisture to crosslink, forming a new polyurethane polymer. By curing the polymer in this way, PURs have performance characteristics that are more enhanced than those of standard hot melts.

Would you like to add information to this article?
Interested in writing or submitting an article?
Have a question about this article?

Have you reviewed the related Knowledge Base areas below?
  • KnowledgeBase: Knowledge Base

  • KnowledgeBase: Adhesives, Gluing and Laminating

  • KnowledgeBase: Adhesives, Gluing and Laminating: Glues and Bonding Agents

    Would you like to add information to this article? ... Click Here

    If you have a question regarding a Knowledge Base article, your best chance at uncovering an answer is to search the entire Knowledge Base for related articles or to post your question at the appropriate WOODWEB Forum. Before posting your message, be sure to
    review our Forum Guidelines.

    Questions entered in the Knowledge Base Article comment form will not generate responses! A list of WOODWEB Forums can be found at WOODWEB's Site Map.

    When you post your question at the Forum, be sure to include references to the Knowledge Base article that inspired your question. The more information you provide with your question, the better your chances are of receiving responses.

    Return to beginning of article.

    Refer a Friend || Read This Important Information || Site Map || Privacy Policy || Site User Agreement

    Letters, questions or comments? E-Mail us and let us know what you think. Be sure to review our Frequently Asked Questions page.

    Contact us to discuss advertising or to report problems with this site.

    To report a problem, send an e-mail to our Webmaster

    Copyright © 1996-2021 - WOODWEB ® Inc.
    All rights reserved. No part of this publication may be reproduced in any manner without permission of the Editor.
    Review WOODWEB's Copyright Policy.

    The editors, writers, and staff at WOODWEB try to promote safe practices. What is safe for one woodworker under certain conditions may not be safe for others in different circumstances. Readers should undertake the use of materials and methods discussed at WOODWEB after considerate evaluation, and at their own risk.

    WOODWEB, Inc.
    335 Bedell Road
    Montrose, PA 18801

    Contact WOODWEB

  • WOODWEB - the leading resource for professional woodworkers

      Home » Knowledge Base » Knowledge Base Article