Sealing End Grain in Outdoor Exposures

      Sealing end grain with epoxy is reported to improve outdoor durability of finishes. April 18, 2015

Question (WOODWEB Member) :
I was wondering if sealing exposed end grain on outdoor furniture, fences and gates would trap moisture behind/under the sealant (epoxy) and increase the likelihood of rot?

Forum Responses
(Finishing Forum)
From contributor R:
I think if you were to seal up the end grain right after a storm you might just seal in the moisture.

From the original questioner:
Yes, I assume if you tried to seal up after a storm then you would seal in moisture. But I am wondering if the wood was sealed when dry, somehow, moisture could migrate to the wood behind the sealer and facilitate rot.

From Paul Snyder, forum technical advisor:

Click to View Member Profile Member Contact Info

Sealing the wood to prevent moisture migration is a good idea and will make the coating last longer. If moisture gets behind the film forming finish, the coating will fail and peel.

From contributor A:
I coated the end grain of a meranti picnic table (fancy) and it has been fine for 15 years sitting in the grass and dirt. I masked the leg exposing about 3/8" of the sides (West System epoxy several coats) and the ends look like plastic. There has been no change. The biscuited/epoxy miter joints have been fine as well. Those are on 3/4 x 3 1/2" wide meranti.

From the original questioner:
I understand that you epoxied the bottom end grain and up about 3/8" on the faces and sides of the legs. Were those faces and sides and other surfaces finished in any way?

From contributor A:
I initially coated it with Penofin. Itís one of those clear diluted resins with lots of UV inhibitors. Itís kind of like exterior Watco oil. Like most of us I didn't put on the yearly coat and left it for five years. After it went kind dirty I sanded it with the random orbit and then added another coat of Penofin. After another five years I sanded it and let it go grey. Now I like the no maintenance. The feet are still plastic. The moisture has plenty of surface area to dissipate through the edge and face grain. We seal the endgrain because it is a weak link (less rot resistant) and it can cause checking.

From the original questioner:
Your comments confirm my impulse to seal the end grain regardless of whether the rest is getting finished or not.

From contributor M:
The more flat/smooth you sand the end grain, the more effective your finish will be. End grain on outdoor stuff is often left sort of rough, since really most folks don't care and think it looks "rustic" or "outdoorsy" if it has some saw marks on it. Sand the end grain with an orbital sander with 150g sandpaper (give or take a grit) just like you would interior stuff, and it will last a lot longer. Itís much more likely to actually seal the wood and not have any open pores from the rough spots to allow moisture to penetrate as much.

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: Finishing

  • KnowledgeBase: Finishing: General Wood Finishing

    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 © 1996-2016 - 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