How to Avoid the Orange Peel Look
I applied a two-component high-solids epoxy sealer to a concrete floor, putting down the first coat in December and the second coat two months later. Prior to applying the second coat, I sanded the floor and wiped it with xylene. I used a squeegee to apply the sealer, then rolled it with an epoxy roller with a 1/8-inch nap thickness. Then I rolled over it with a spike roller. The sealer did not lay out smoothly, and is very uneven and rough. What went wrong, and how do I fix it?
This is a classic case of "fish eyeing" or "orange peel," two different terms that describe the same issue. It's caused when the second coat of sealer fails to "wet out" or become one with the first sealer coat. This can be due to chemical or dirt contamination or because the surface is just too hard and smooth to accept the new coat of sealer. By wiping the floor with xylene, you may have left behind a chemical residue. Or maybe you didn't sand the surface enough prior to applying the second coat of sealer. How did you sand, and with what grit of sandpaper or screening? When sanding, you have to micro-scratch the surface enough to reduce the surface tension that can prohibit the second coat from adhering to the first coat. The two sealer coats look like they are repelling each other, which can occur with high-solids coatings if the first coat is not prepared properly.
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Author Chris Sullivan, ConcreteNetwork.com technical expert and vice president of sales and marketing for ChemSystems Inc.