Troubleshooting Bubbles in Lacquer

      "Solvent pop" may be causing bubbling in a lacquer coat. Solutions include applying lighter coats, or using retarder in place of straight thinner. October 2, 2005

Question
I'm spraying a lacquer on red oak over a white wash or pickling stain. I'm using an airless spray rig with a fine finish tip. Bubbles keep appearing as it dries. I used this brand lacquer before and never had a problem. It's a Kelly Moore brand that is manufactured by Trinity Coating company. Both stain and lacquer are made by the same company. I'm in Texas, where the humidity is always bad, but have never had this problem before. I'm a cabinet builder, not a finisher, but sometimes get left holding the bag when the finisher doesn't show.

Forum Responses
From contributor G:
Are the bubbles showing in the open grain? If so, it's likely the solvent coming out. Let the pickle dry longer.



From contributor W:
There's another possibility if the bubbles are in the grain: solvent pop. Airless rigs can lay down a thick coat of material, which in warm weather can skin over before the lacquer solvent has worked its way out of red oak's large pores. When it finally does, it creates a bubble or a crater. Easy fix: Add some retarder as per manufacturer specs, and/or lessen the thickness of the coating by reducing tip size, speeding up the gun movement, or adding a bit of thinner.


From contributor M:
Do not apply heavy coats, and allow enough time for each coat to release the slower solvents before you apply the next coat. This is a common problem with oak.


From Paul Snyder, forum technical advisor:
I usually start with a low solids vinyl sealer on oak - it seals the pores and prevents air bleed-out that causes bubbles, and it levels the pores better than a high solids sealer. You can thin the lacquer for the same effect (lower the solids content). Thinning, including a small amount of retarder, will help with air bleed and the solvent pop that was mentioned.


From contributor R:
Try eliminating the thinner, and add retarder only. Retarder is just a slow thinner. Higher temperatures naturally lower the viscosity of the finish, so all you are trying to do is allow it to stay wet long enough for the atomizing air and solvents to gas off. Having a faster thinner in the mix could actually be a source of the bubbles, even if you have added a retarder.


From contributor T:
Contributor W hit on the thing that we had trouble with. I had this happen on some high-build white primer a week ago and it turns out to be exactly what contributor W mentioned - skinning over before what's under it can cure, causing a bubble. I found I had to sand about 90% of the primer off before getting a smooth finish. And the thinner made it worse, partly because, at the time, we were out of standard thinner and I tried some cleaning-grade thinner. I wound up with an acne-outbreak monster.


From the original questioner:
Thanks. I think I'm trying to rush too much and spraying too thick. It's always good to have advice from the experts.

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