Mistake 1: No Slab pH Test Before Sealing

Concrete cures alkaline (pH 11-13). Sealers bond best to concrete that has cured down to pH 8-9, which usually takes 30-60 days after a pour. Sealing fresh concrete creates bubble-formation and adhesion failure. Most contractors skip the pH test, seal whatever you have, and the sealer fails within 18 months. Always ask: did you pH-test the slab before quoting the seal? If no, find another contractor.

Mistake 2: Cold-Water-Only Pressure Wash

Cold water removes surface dirt but does not lift oil or biological staining out of the porous concrete matrix. Hot water (180°F+) thins petroleum oils and breaks the bond, then a properly-spec’d alkaline degreaser emulsifies the oil into the wash water. The cleaner the surface, the better the sealer adheres. Cold-water-only cleans get visible result + invisible failure: the surface looks better short-term, the sealer fails in 12-18 months because contaminants stayed locked in the pores.

Mistake 3: No Written Sealer Specification

“We’ll seal it” is not a spec. The right answer names the product (e.g. Prosoco Saltguard WB, SureCrete Eco-Tuff, etc.), the application rate (typically 200-400 sq ft per gallon), the number of coats (most need 2), and the warranty period. If your quote does not name the sealer product and application rate, the contractor is winging it. Walk away.

Mistake 4: No EPA Water Reclamation on Commercial Concrete

Federal Clean Water Act prohibits oil-contaminated wash water from entering storm drains. For commercial driveways, parking lots, and shop floors, the contractor must vacuum-recover wash water and dispose of it at a permitted oil-water separator facility. Without it: $2,500-$11,000 per occurrence in EPA fines (the citation goes to the property owner, not the contractor). Always ask: do you bring vacuum reclamation? Get a yes + see the equipment, or do not hire.

Mistake 5: Paying for “Deep Clean” Without Knowing the PSI

“Deep clean” is marketing language. The functional answer is PSI (pressure per square inch) and surface-cleaner type. For typical concrete: 3,000-3,500 PSI through a 25-degree fan tip is appropriate for general dirt. For oil staining: hot water + degreaser dwell + surface cleaner pass. Asking the contractor “what PSI will you use” filters out residential-grade operators using consumer-pressure-washer equipment that cannot deliver real cleaning power.

Mistake 6: No Surface-Prep Walkthrough

Cracks should be filled before sealing. Spalled areas should be patched. Joints should be cleaned out and possibly re-caulked. Most concrete jobs need 30-60 minutes of prep before the actual cleaning starts. If your contractor jumps straight to pressure-washing without a prep walkthrough, they are skipping the work that determines whether the sealer lasts 18 months or 5 years.

Mistake 7: No Warranty on the Sealer

A properly-installed concrete sealer carries a manufacturer warranty (1-5 years depending on product). The contractor passes that through to you in writing. No warranty = no accountability. If the seal fails in year 2 you are on your own paying for a re-do. Always get the warranty terms in writing as part of the quote.

Frequently Asked Questions