Andy Miller’s Epoxy 101: Thickeners & Viscosities

Here is the video that will demystify and clarify all of your epoxy thickening questions and concerns. Andy Miller suffered through some overly runny epoxy that set back his Moppie transom job, so this week he’s getting down to the ounces to determine the exact ratio for the three most used epoxy viscosities: ketchup, mayonnaise, and peanut butter. We’re not quite cooking in Andy’s boat shop kitchen, but he is comparing the amount of silica to add to your epoxy resin mixture to these three very different consistencies. This handy information will help you fully customize your epoxy mixture to be as thin or thick as you need. And it works for both polyester and epoxy resins.

Here’s the quick recap of the three viscosities Andy mixes up:

Ketchup: It’s the loosest, runniest mixture that will run when placed on a vertical surface.

Mayonnaise: Best for laminating and bonding wood to wood. It’s thick, but still loose and will sag a bit but shouldn’t be “runny” like ketchup. This mixture helps when bonding to fill gaps and avoid dry seams.

Peanut Butter: This is the thickest mixture for when you are looking to get some build and thickness on the surface. Just like Bondo or TotalFair – you can use it to fill and fair out surfaces to be smooth. It won’t sag at all – and stays put when vertical, just like peanut butter would.

Tune in to today’s video of the week and let Andy know in the comments if you’ve had runaway epoxy ruin a job. Have you tried thickeners? What’s stopping you? Now you have the knowledge and resources to get the right viscosity right out of the mixing cup. Enjoy!

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