How can I preserve plywood?


I want to preserve a sign made of 3/4 plywood that was painted with oil based paint and hung on our barn 40 years ago. It's now hanging in my garage for a keepsake. I'd like to keep it the way it is as much as possible.

q how to preserve plywood
  6 answers
  • Kelli L. Milligan Kelli L. Milligan on Aug 20, 2019

    Sure, just apply several coats of oil based polyurethane. Front and back. If you are exposed to the weather use Marine varnish

  • Gk Gk on Aug 20, 2019

    You can use water based poly over oil based paint. if you use water based poly it will not yellow over time like oil based poly. As longas you plan to keep this sign stored inside your garage it should be fine.

  • Susan Susan on Aug 21, 2019

    Honestly, it's not going anywhere! After 40 years outside, hanging in your garage will be a vacation for that fabulous keepsake! I wouldn't do anything...might alter the appearance too much. Antiques need to stay antique. Watch Antiques Roadshow? Changing an original surface is almost never recommended. It's beautiful just the way it is.

  • William William on Aug 21, 2019

    Three coats of a water based polyurethane. Stays clear, won't yellow.

  • Baxter Baxter on Aug 21, 2019

    Use a good Polycrylic---about 2-3 coats. It will not negatively alter the sign and will protect it from dust and dirt so that it will not dry rot.

  • Lisa Lisa on Aug 21, 2019

    do not use minwax high gloss poly Spray.. it definitely yellows on canvas.

    i would do absolutely nothing with it, it’s beautiful just the way it is.. if it ever gets weak, use gorilla clear wood glue on the backside of it or the tyvak silver tape. The gorilla clear doesn’t yellow either..