3 Ways to Prepare Surfaces for Epoxy Recoating

Whatever project you’re working on, you’ll need several coats of epoxy resin and hardener. Most projects require between two and four coats. However many coats you plan to apply, it is essential to recoat at the right time and in the right way while ensuring your surface is properly prepared.

How you prepare a surface for recoating with epoxy depends on whether the epoxy you’re covering is wet or dry.

Suppose the epoxy is wet but cured enough to support the weight of the next coat. In that case, you can apply another coat to create a “primary bond,” which is a bond between the epoxy layers at the chemical level (intramolecular bonding). However, as your epoxy blend dries, it becomes harder to create a primary bond, requiring a secondary bond (intermolecular bonding). Secondary bonding includes dipole-dipole bonding and hydrogen bonding. Mechanical bonding can also occur when liquid adhesive flows into surface cracks and cures, effectively “keying in” to the surface.

Below, we outline three main ways to prepare your epoxy-coated surface—whether wet or dry—for its next coat.

1. How to Prepare a Completely Cured Epoxy Surface

If your epoxy has fully cured, the first step is to check for amine blush.

Amine blush appears as a wax-like film on cured epoxy surfaces. It is a normal byproduct of the curing process and is more noticeable in cool, moist conditions. Although amine blush can prevent bonding to additional epoxy layers, it is water-soluble and easy to remove.

To remove amine blush, wash the surface thoroughly with clean water and an abrasive pad. Then, dry it with fresh paper towels to prevent the amine blush from drying back onto the surface. Next, sand any glossy areas with 80-grit sandpaper to create a rough texture for better adhesion. Once the dust is cleaned away, your surface is ready for the next coat of epoxy.

2. How to Recoat a Recently Epoxy-Coated Surface: The Sticky Tape Test

If you have recently applied epoxy, you can apply the next layer when the previous coating has reached the sticky stage.

To check if the epoxy is appropriately sticky, perform the “sticky tape test.” When you touch a piece of sticky tape with your finger, you feel the stickiness, but no glue transfers to your skin. Similarly, if you press a gloved finger onto your epoxy-coated surface and it feels tacky—but no epoxy comes away—you’re at the right stage to apply another coat.

If a significant amount of epoxy transfers onto your finger, the surface needs more curing time. Conversely, if there is no tackiness at all, you’ll need to treat the surface as fully cured and follow the steps outlined in method 1.

3. Using Peel Ply

The third method for preparing a surface for recoating with epoxy is to use peel ply.

Peel ply, also known as release fabric, is a synthetic cloth designed to enhance the texture of an epoxy-coated surface. It does not stick to the epoxy; instead, it peels away, leaving a perfectly textured surface ready for the next epoxy layer.

To use peel ply, apply your epoxy blend to the surface and drape the peel ply on top. Smooth it out with a spreader to remove any air bubbles. Once the epoxy has cured, simply peel off the fabric, and your surface is ready for recoating.

Keep in mind that peel ply is best suited for flat surfaces. It does not work well on curved areas, as any wrinkles left in the peel ply will cure into the epoxy.

Thanks to Hamish Cook for his contribution.