Slow Drying and Curing in Refinish Jobs

      Troubleshooting the cause of splotchy curing, where some areas in a refinished piece don't cure or dry for a long time.September 3, 2011

We spray magnamax thinned down with fast thinner. From time to time we notice that some areas don't dry and cure. We’re using different woods and different types of ML Campbell lacquers. It seems to be something in the prep or wood. A light mist coat over the areas seems to dry it out. Just wondering if anybody ever came across this or has any ideas as to what causes it. We are a refinishing company only. Out process is:

Strip and dip.
Dry for a few days.
Sand to 320.
Seal/stain and three coats on top of MagnaMax.

Forum Responses
(Finishing Forum)
From contributor G:
Why are you using fast thinner and is it MLC thinner? You should be using standard thinner. The fast thinner is now the same as the economy thinner which is really used for cleaning because it is inexpensive.

From contributor P:
I would look into the following:

- Try a slower reducing solvent to allow the matting agent to flow out more evenly before the coating starts to kick.

- Ensure that you are over lapping 50% on each pass of the spray gun to get even coverage.

- Allow the coating to dry longer between coats to ensure all the tail solvents are out before entrapping them with a subsequent coat.

From contributor C:
I would only sand to 180 grit. 320 can cause polishing of the wood, sealing the pores.

From contributor G:
I didn't even catch the 320 grit. Yes, in between coats 320 is fine. But on raw wood MLC recommends not going above 150.

From contributor K:
Take note of the wood type and of the areas that stay wet. One bet would be that the anti-evaporation stearates in the stripper have made their way into some softer or spongier areas that the rinse and neutralize do not wash out. Sort of like washing peanut butter out of a sponge. These bloom up into the lacquer and keep it from curing. Sometimes a few days dry is not enough. On really soft spots, it may never dry fully.

From contributor A:
Contributor K is right about the cause. To fix this problem, simply wipe a few times with naphtha on a dampened rag, works like a charm.

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: Refinishing

    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 © 1996-2019 - 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