Does Sodium Hypochlorite Bleach Surfaces?
Does Sodium Hypochlorite Bleach Surfaces? How to Use It Safely in Soft Washing
Sodium hypochlorite (SH) is one of the most effective tools in a professional exterior cleaner’s arsenal. It’s strong, reliable, and when used properly, removes mold, mildew, algae, and organic stains quickly.
But what many pros and homeowners overlook is that sodium hypochlorite is also a bleach—and like any bleach, if used incorrectly, it can damage or discolor surfaces. In this article, we’ll walk through:
- What sodium hypochlorite does during soft washing
- What materials are at risk
- How to prevent bleach-related mistakes
- Safer alternatives when needed
Understanding Sodium Hypochlorite in Exterior Cleaning
Sodium hypochlorite (NaOCl) is used in professional-grade soft washing in concentrations of 5%–12.5%. It's most effective at:
- Killing biological growth (algae, lichen, moss)
- Whitening darkened, discolored surfaces
- Sanitizing areas exposed to contamination
But the same chemical power that eliminates algae can also degrade paint, stain wood, or streak siding—if the chemical is too strong, left too long, or applied without care.
Surfaces Most Vulnerable to Bleaching or Damage
Not all surfaces react to SH the same way. Below are some of the most common at-risk materials and how to protect them.
1. Painted Surfaces
- Risk: Fading, bubbling, or chalking
- Prevention: Use SH at a lower concentration (0.25–0.5%) and never allow it to dry on paint.
2. Wood Decks & Cladding
- Risk: Greying, warping, or surface damage
- Prevention: Pre-wet the wood, use a diluted SH mix, and rinse thoroughly. Use wood-specific cleaners when possible.
3. Coloured Render or Stucco
- Risk: Irregular fading or bleach blotches
- Prevention: Apply with a surfactant (like Blue Crush) for even coverage and controlled dwell time. Never overspray on sunny days.
4. Metal Surfaces (Aluminum, Copper, Zinc)
- Risk: Corrosion or streaking
- Prevention: Always pre-wet, avoid direct application, and rinse any overspray immediately.
5. Natural Stone & Brick
- Risk: Efflorescence or etching from overexposure
- Prevention: Apply a controlled mix with rinse water management. Consider post-treatment neutralization.
How to Minimize Bleaching Risk: Best Practices
These are the habits top soft washing professionals use to keep their work clean, safe, and damage-free:
1. Mix Properly for Each Surface
Using a proportioner, Dosatron injector, or measured batch mixing is essential. For example:
- Siding: 0.5–1%
- Roofs: 3–4%
- Painted wood: 0.25–0.5%
LNI Equipment offers proportioner kits and SH tanks that help you control ratios and avoid over-applying bleach.
2. Use a Surfactant
A surfactant allows your SH solution to cling longer, clean better, and rinse more easily. We recommend:
- Blue Crush for cling and foaming
- Roof Guard for roof dwell and scent masking
This not only improves results but also reduces chemical usage and environmental risk.
3. Never Let It Dry
Letting SH dry on a surface is the most common cause of streaks and discoloration. Keep the surface damp during application and rinse after dwell time.
Work in manageable sections and avoid washing in the midday sun if possible.
4. Rinse Surrounding Areas
Soft-wash runoff can damage plants, paint, and fixtures if not managed. Best practices include:
- Pre-wet all landscaping
- Rinse after application
- Use neutralizers where needed for added safety
When to Avoid SH and Choose an Alternative
In some cases, it’s better to skip SH altogether:
At LNI, we’re happy to recommend the right product for the job—even if it’s not SH-based.
| Situation | Alternative Product |
|---|---|
| Wood brightening | Wood cleaner/oxalic acid |
| Rust Stains | Rust remover (non-SH based) |
| Oily Driveways | Degreaser like Green Guard |
| Long-term Prevention | Biocide or residual moss control |
Final Thoughts: Effective, Not Aggressive
Sodium hypochlorite is a top-tier cleaner when used with care and experience. But if used recklessly, it becomes a liability.
Always mix responsibly. Always rinse thoroughly. Always protect your surfaces.
Need reliable sodium hypochlorite, surfactants, and mixing tools?
LNI Equipment Stocks:
- 12.5% SH in bulk or per gallon
- Blue Crush surfactant
- Proportioners and injectors
- Neutralizers and plant rinse kits