What Is Sodium Hypochlorite?

Quick Answer: Sodium hypochlorite is a powerful oxidising cleaning chemical widely used in softwashing to remove organic contamination from exterior surfaces. It is commonly used to tackle algae, mould, mildew, moss, lichen and other biological growth.

What Is Sodium Hypochlorite?

Sodium hypochlorite (NaOCl) is a chlorine-based chemical commonly used in cleaning, sanitising and disinfection applications.

Within the softwashing industry it is one of the most widely used cleaning agents because of its ability to break down organic contamination quickly and effectively.

Many professional contractors simply refer to it as "hypo".

How Does Sodium Hypochlorite Work?

Sodium hypochlorite works through a process known as oxidation.

When applied to organic contamination, it breaks down cell structures and disrupts biological growth.

This oxidation process helps reduce visible staining and contamination on exterior surfaces.

Learn more in our guide: How Does Sodium Hypochlorite Work?.

What Is Sodium Hypochlorite Used For?

Professional softwash contractors commonly use sodium hypochlorite on:

Roof tiles
Render
Patios
Driveways
Concrete
Brickwork
Cladding
UPVC surfaces

The exact dilution ratio depends on the surface being treated and the level of contamination present.

Why Is Sodium Hypochlorite Popular In Softwashing?

Sodium hypochlorite is popular because it is:

Highly effective against organic contamination
Suitable for many exterior surfaces
Cost-effective when diluted correctly
Widely available within the cleaning industry
Compatible with softwash surfactants

Many contractors combine sodium hypochlorite with a specialist surfactant to improve coverage and dwell time.

What Strength Of Sodium Hypochlorite Is Used?

Professional-grade sodium hypochlorite is commonly supplied at concentrations around 14% to 15%.

For softwashing applications it is normally diluted before use to suit the surface and cleaning requirements.

The final working strength can vary significantly depending on the application.

What Is The Role Of A Surfactant?

A surfactant helps the solution spread more evenly across the surface.

It reduces surface tension, improves cling on vertical surfaces and helps maximise contact between the cleaning solution and the contamination.

This is why many contractors use products such as Clever Wash alongside sodium hypochlorite.

Learn more in our guides:

Can Sodium Hypochlorite Be Used On Every Surface?

No.

Different materials react differently to cleaning chemicals.

Surface identification, testing and correct application methods are important before treatment begins.

Professional assessment is recommended where there is uncertainty.

How Should Sodium Hypochlorite Be Stored?

Sodium hypochlorite should be stored in suitable chemical-resistant containers away from excessive heat and direct sunlight.

Exposure to sunlight and high temperatures can accelerate degradation and reduce effectiveness over time.

What Safety Precautions Are Important?

Because sodium hypochlorite is a strong chemical, appropriate safety measures should always be followed.

Wear suitable PPE
Follow COSHH guidance
Read product safety information
Protect surrounding areas
Prevent uncontrolled runoff
Store and handle responsibly

Learn more in our guides:

Is Sodium Hypochlorite Legal For Softwashing In The UK?

This is one of the most common questions asked by contractors.

Professional users should always ensure products are used responsibly, safely and in accordance with relevant regulations and manufacturer guidance.

Learn more in our guide: Is Sodium Hypochlorite Legal For Softwashing In The UK?.

Why Is Training Important?

Understanding oxidation, dwell time, surfactants, safety procedures and application techniques is fundamental to professional softwashing.

Training helps contractors understand how these factors work together to achieve safe and consistent results.

Learn more in our guide: What Is CPD Certified Softwash Training?.

Summary

Sodium hypochlorite is one of the most widely used chemicals in professional softwashing. Its ability to break down organic contamination through oxidation makes it an important tool for cleaning exterior surfaces when used correctly, safely and responsibly.

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About SoftWash UK

Founded by Mark Cave in 2015, SoftWash UK supplies professional softwashing chemicals, equipment, compliance resources and CPD-certified training throughout the United Kingdom.

SoftWash UK helps contractors understand sodium hypochlorite, softwashing chemistry, surfactants, dwell time, compliance requirements and professional application techniques through practical training and technical support.