Stripping

Sealer makers name strippers and use the word as an instruction. SEK-Surebond's data sheet for SB-1300 says to "use Efflo Off for efflorescence cleaning and SureStrip to remove previously applied sealer, other than SB-1300."

Techniseal's Natural Look (NS) data sheet gives the same instruction in general form: "with the appropriate stripper, remove any unknown coating that was previously applied." Which stripper fits a given sealer is that product's own maker instruction, never a general rule.

For a clouded sealer on interlocking concrete pavers, ICPI's own remedy is stated plainly: "the sealer must be removed or re-dissolved," and it routes the reader to "consult your sealer supplier for advice on treating this situation."

ICPI singles out urethane removal as harder chemistry: "if urethane sealers must be removed, methylene chloride or sand blasting is often necessary," and "methylene chloride is a hazardous chemical, and is not acceptable for flushing into storm drains. It should not be allowed to soak into the soil." Its conclusion follows from that warning: "therefore, urethane removal is best handled by professionals." How ICPI contrasts worn acrylics, cleaned and resealed, with urethanes that cannot simply be re-coated is set out at what happens when a paver sealer wears.

ASCC's troubleshooting for decorative concrete sealers repeatedly lands on the same word once a solvent wash has not fixed a whitened sealer: "otherwise, stripping and sealer re-application will be necessary."

For a sealer that has already yellowed, ASCC is just as direct: "once a sealer has yellowed the only proper fix is to strip and reseal, otherwise the yellow coating will be trapped under the new sealer," a question argued in full at does paver sealer turn yellow.

ChemMasters draws a line between the two procedures rather than treating them as one. Correcting a bubbled or blushed film with solvent, it says, "is not a method for removing the sealer; it is a method intended to correctly re-form the acrylic film, and get rid of the bubbles." Stripping is the further, separate step of taking the film off entirely.

None of these lines is a general rule for when a sealer has to come off. ICPI's is written for a clouded sealer on interlocking concrete pavers, ASCC's for decorative concrete sealers and ChemMasters' for acrylic films, and each stripper named above belongs to its own maker's instructions.

Peeling is a different failure with its own causes, set out at why is my paver sealer peeling. Whether a new sealer can go over an old one instead, matched or mismatched, is answered at sealing over an old sealer.