In order to accurately remove a concrete sealer you first need to determine the type of sealer that was initially applied. If you already know you can skip this step.
How to determine if concrete was sealed with a water-based concrete sealer or a solvent-based concrete sealer:
- Pour a small amount of Xylene on an area that is still coated by the previous concrete sealer.
- Allow the Xylene to sit for 20 seconds. Remove any excess.
- Touch the area and if it is tacky or sticky the surface was sealed with a solvent-based sealer.
- If the concrete is not tacky or sticky the concrete was sealed with a water based sealer.
How to remove a solvent-based concrete sealer:
Start by removing any visible peeling and flaking and use a solvent based stripper such as Xylene to remove the previous sealer. (If concrete was dyed or stained, using Xylene can damage or change the color of the concrete.)
- Pressure wash the surface and allow concrete to completely dry.
Instead of removing a previous solvent-based acrylic sealer try resealing it! You can apply a solvent-based acrylic sealer directly to the concrete without needing to remove the old sealer. First try and remove any visible peeling and flaking and then reseal according to the instructions.
How to remove a water-based concrete sealer:
- Use a product such as Aqua Mix's Sealer and Coating Remover.
- You can also try acid etching the concrete (followed by neutralizing)
- You can mechanically scarify the concrete to remove the previous sealer.
Instead of removing a water-based concrete sealer by chemically stripping or etching try pressure washing it! This method works best if the previous concrete sealer is old, faded and almost worn away.
Generally speaking, in most cases, a new solvent-based concrete sealer can be applied to a surface previously sealed with a solvent-based concrete sealer; however, it cannot be applied over a surface previously sealed with a water-based concrete sealer. If you previously applied a water-based concrete sealer and are now looking to seal with a solvent-based concrete sealer you need to remove the water-based concrete sealer since the solvents will eat or soften the existing water-based concrete sealer, destroying both coatings. Water-based concrete sealers can be removed through chemical etching, aggressive pressure washing or mechanical scarification.
If you previously applied a solvent-based acrylic concrete sealer and are now looking to seal with a water-based acrylic sealer you need to remove the solvent-based acrylic sealer concrete since the water-based concrete sealer will be unable to properly adhere to the solvent-based concrete sealer. Start by removing any visible peeling and flaking and use a solvent-based stripper such as Xylene to remove the previous sealer.
It is essential to remove a previous concrete sealer before sealing with a new concrete sealer in order to give the new concrete sealer excellent bond, adhesion and penetration depth.