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Removing Bubbles and Roller Marks in a Sealer

Question:

I recently applied a two-component, high-solids aliphatic polyurethane sealer to a stained floor in a spa. First, I applied the primer coat with a roller and then applied the polyurethane, which has a longer pot life, with an airless sprayer. While applying the primer on the first half of the floor, I could see roller marks and bubbles and the primer started to string up on me. I mixed a new batch and proceeded to finish rolling the rest of the floor but at a much faster pace, and I seemed to have no problem. But now roller marks are visible throughout the entire floor, not to mention the bubbles.

To remove the bubbles, I was told by the sealer manufacturer to go over the floor with a floor buffer or 150-grit sandpaper and then seal again. But will buffing be aggressive enough to take out the marks? Also, should I apply the primer using a sprayer instead of a roller, and should I mix smaller amounts of the sealer? I think I may have rolled on the primer too fast producing the roller marks. What do you recommend to fix the issue?

Answer:

Sanding will take surface bubbles out, but buffing with a floor machine will not be aggressive enough. If the bubbles go deeper than the surface, you may need to strip and start over. My suggestion is to try sanding out the marks and then reapply your topcoat. If this does not work, strip down to a point were no roller marks or bubbles appear and start over. Do a test area before doing the entire floor.

I am not a fan of rolling in general, especially heavier bodied materials like epoxies or polyurethanes. All rollers produce lines, with more material coming off the ends of the roller as it moves across the surface. Depending on the material used, application temperature and pot life, the roller lines may or may not even out. The speed of rolling, the amount of material on the roller and the weight pushing down on the roller also play a role in leaving roller marks. Picture a car tire that has mud on it. If you drive slowly, the mud comes off the tire evenly. If you speed up, the mud flies all over and leaves more prominent marks on the outside edges of the tire. Heavy-bodied materials are always best applied in small batches and with a push-pull applicator such as a lamb's wool or micro-fiber pad or a T-bar.

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