Troubleshooting Shadow Lines in Veneer

      A veneer manufacturer gets help diagnosing a problem with lines appearing on fresh veneer after finishing. June 28, 2010

I build my own cores using MDF with a solid wood edge to allow me to create profiles on my tops. The problem I am having is that once my tops are sanded and clear coated, a shadow line appears where my MDF attaches to my natural wood. What is causing this problem, and how can I correct it?

Forum Responses
(Veneer Forum)
From contributor D:
This is called telegraphing and is caused by the substrate and solids moving at different rates, in response to changes in relative humidity.

Minimize the swings of humidity the tops are exposed to. There is only so much you can do here, but it will help. Crossbands on both faces (to preserve balance) will minimize the telegraphing. The thicker, the better, within reason. Another strategy is to add the solid wood flush to the veneer face, with a slight V-joint. Any difference will get lost in the V.

From contributor V:
Let your solid edging dry more before you flush trim and veneer. Are you hot pressing? The heat from the press can dry out solid which has a higher humidity, causing it to shrink. It usually only goes one way, in that the solid shrinks, and that is it. This also happens with translucent veneers such as English sycamore, and sometimes maple. In that case you are seeing the darker MDF/particleboard through the veneer.

From contributor J:
Try minimizing the solid on the top edge to about 1/8". You can rabbet out the bottom thicker there for your profile. The 1/8" generally doesn't telegraph and usually gets lost in a radiused edge.

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: Veneer

  • KnowledgeBase: Veneer: Processing And Manufacturing

    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