Why does epoxy "shrink"?

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I used HXDZFX epoxy over unicorn spit to seal the inside of a wood tray. After it cured, I noticed that it was uneven around the edges. Like it had shrunk away from the sides. I poured a second layer on making sure it was covering the edges and smoothed to the center. Alas it cured the same. Can anyone explain why?

  7 answers
  • Beth Beth on Nov 25, 2019

    Was it near a heat source at all? That can make it shrink.

  • Megan Megan on Nov 25, 2019

    Hi! Is your tray level? Are you pouring the epoxy on a level surface? I've run into this before with projects. But typically it is because something is not level.

  • Feather Feather on Nov 25, 2019
    Yes it's level. I checked with a level in all directions.

    • Megan Megan on Nov 26, 2019

      My only other thought would be of a chemical reaction with a material that was in the tray or the unicorn spit.

  • You might want to reach out to the manufacturer for some answers there, it could be lots of things including that's just what the product does when it dries.

  • Lori Lori on Mar 20, 2021

    I have same problem with shrinkage on my projects. It's not warm in my shop so it's not the heat, my project is level but it shrinks way to much. Help

  • Kyle Kyle on Nov 28, 2021

    Some paints and epoxies depending on their chemical makeup will shrink after curing due to solvents evaporating during the curing process depending on what you're using and what chemicals are in it there may be shrinkage due to evaporating solvents that are used to make the actual product unless you're using a epoxy that's 100% solids you're going to experience some level of shrink and very few epoxies on a consumer basis are 100% solid