Scraping Glue Before Planing

      Dried glue squeeze-out can damage planer knives, so it's a good idea to clean glued-up material before further machining. April 13, 2010

My guys in the shop take the time to scrape off the dried glue when we make stave cores for doors. They say they are trying to prevent damage to planer knives. Do you think it is necessary to do this or is it wasted time and effort?

Forum Responses
(Architectural Woodworking Forum)
From contributor W:
I personally like to get my excess glue off earlier before itís dried hard. It is very good to remove it before final planing or wide belt sanding. The dried glue is very sticky when feeding through machinery, and I'm sure more dulling than pure wood to the knives. If left to the final planing and sanding it causes further variance in the sanding operations and lower quality results, right on through the end, even in the finish. I have seen a coarse belt multi system that was designed to remove all residue at the first belt. Then I do a final sanding.

From contributor D:
Cured glue damage to planer knives is unlikely, with its density much less than most woods. If the glue is still somewhat gummy, then yes it may stick inside the gullets and dust hood, inhibiting chip flow and heat dissipation, and heat can anneal your knives. It is not good practice to plane them until they are cured anyway, as the slight swell from the moisture in the glue hasn't gone away, and you may be laminating to a surface that will eventually cure with slight ridges at each joint, which can possibly telegraph out or even crack your veneer. Glue that is even cured hard is much worse on widebelt sanders, a much bigger worry in my opinion.

From Gene Wengert, forum technical advisor:
Dried glue can indeed damage planer knives, so removal before planing is important. Similar comments about sandpaper. Scraping, often before it hardens, is the usual approach. Note that squeeze-out is good in that it indicates that sufficient adhesive was used. Lack of squeeze-out means a starved joint or part of the joint.

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: Solid Wood Machining

  • KnowledgeBase: Solid Wood Machining: General

    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 © 1996-2020 - 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