Spray Finishing Aluminum

      Tips on cleaning and finishing sheet aluminum. September 27, 2008

I had to spray some new aluminum panels so I used acid etched primer first than sprayed Ben Moore satin oil finish on top. When I sprayed on another coat after the previous one dried the whole finish got spider web look to the finish. What happened?

Forum Responses
(Finishing Forum)
From contributor C:
Why oil? There is the problem.

From contributor S:
Tough situation - aluminum is a different critter. As with any paint job, the initial surface must be absolutely clean and free of any oils.

When extruded aluminum is "raw", it is very porous. I suspect there are many treatments designed to fill the pores, all of which have the potential to affect your paint job. At the very least, the aluminum will have oils and milling fluids imbedded in the pores. I suspect most milling/cooling oils used are water soluble - soap and water should break it down.

If the extruded aluminum was anodized (a process where pores are filled), then you have a situation where your new finish may not be compatible with the anodize finish. I do not know about cast aluminum (picture a motorcycle engine), but I suspect cast would be much less porous than extruded. They electrostatically apply and bake paint onto cast aluminum all the time. You need to know more about the aluminum itself and how it may have been treated before you got it. Many automobiles over the years have had aluminum sheet metal body parts - sheet aluminum is an extruded product. A visit to your favorite body shop might be worth your time.

Brake cleaner - available at AutoZone - is a very effective remover of oils from metals. It seems to cut everything and evaporates very quickly. Also, some good old lacquer thinner would likely work as well. All this to say "clean it, clean it, clean it, clean it some more, and then experiment".

From contributor R:
Aircraft guys do this all the time. I worked at Stits Polyfiber coatings for a while in my youth and they use Aluma-Dyne E-2300 conversion coating which is a chromic acid solution for clear coating aluminum and Aluma-Dyne E-2310 phosphoric acid etch/brightener which is an etch for painting.

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

    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 © 1996-2018 - 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