CSLB C-33 Painting & DecoratingSurface PreparationMedium
A painting contractor is preparing an interior concrete floor for a new epoxy coating. The floor is clean but has a very smooth, troweled finish. To ensure proper adhesion of the epoxy, what surface preparation method is most critical for this type of substrate?
- ASweeping and vacuuming thoroughly to remove dust
- BFilling any minor cracks with a flexible caulk
- CApplying a solvent cleaner to degrease the surface
- DAcid etching or mechanical abrasion to create a profile
Show answer & explanationAnswer & explanation
Correct answer: D. Acid etching or mechanical abrasion to create a profile
Epoxy coatings require a profiled surface for mechanical adhesion. A smooth, troweled concrete finish lacks the necessary profile. Acid etching (for smaller areas) or mechanical abrasion (grinding/shot blasting) creates the required Concrete Surface Profile (CSP) for proper epoxy bond.
Why the other options are wrong
- A. Sweeping and vacuuming are basic cleaning steps, not sufficient for profiling a smooth concrete surface for epoxy.
- B. Filling cracks is a repair step, not the primary method for creating adhesion on a smooth surface.
- C. Degreasing is important but doesn't create the necessary surface profile for epoxy adhesion on smooth concrete.
Concrete Surface Profile (CSP)
A standardized measure of the roughness of a concrete surface, crucial for the adhesion of coatings like epoxy.
- Created by mechanical abrasion or acid etching.
- Ranges from CSP 1 (fine) to CSP 10 (very rough).
- Specific CSP levels are required by different coatings.
Memory trick: Smooth concrete needs a 'tooth' for epoxy to cling.