Underground mines are dark, enclosed and difficult to illuminate.
The surfaces are often uneven. They may also be dark in colour, dusty or hard to distinguish from the surrounding area. Because of this, mines use different methods to support visibility underground.
One of those methods is whitewash.
Whitewash is a light-coloured coating applied to selected underground surfaces. In mining, it is often used on walls, sidewalls and other areas where better light reflection is required.
The reason is simple. Lighter surfaces reflect more light than darker surfaces.
This makes whitewash a practical part of underground visibility planning.
What is whitewash?
Whitewash is a light-coloured coating used on walls and other surfaces.
In many cases, whitewash refers to a lime-based coating. Limewash is usually made from lime and water and has been used for many years as a simple white surface coating.
In underground mines, the purpose is not decoration. The purpose is usually linked to visibility, light reflection and surface contrast.
A whitewashed wall gives workers a lighter background than dark rock. This may make the area easier to inspect and understand visually.
Why visibility is a challenge underground
Lighting an underground mine is not the same as lighting a normal building.
The space is narrow, dark and constantly changing. There may be dust, equipment, uneven ground and low visual contrast.
NIOSH explains that underground mines are difficult to illuminate because they include confined spaces, dust, poor light-reflecting surfaces and low visual contrast. It also explains that mine lighting is important for seeing ground conditions, equipment and possible hazards.
This is why mine visibility is not only about adding lights. It is also about how the surrounding surfaces interact with that light.
How whitewash fits into mine lighting
Whitewash is used because it changes the surface colour.
A dark surface absorbs more light. A lighter surface reflects more light back into the area. This is known as reflectance.
The Mine Health and Safety Council refers to whitewash or light-coloured shotcrete on sidewalls as a way to increase reflectance and general illumination levels in the underground visual environment.
That is the key point.
Whitewash is not the lighting system itself. It is part of how the underground surface responds to the lighting already in place.
Where whitewash may be used
Whitewash is usually considered in areas where visibility is important for daily movement, work or inspection.
This may include:
- travel ways
- loading areas
- workshop areas
- equipment routes
- sidewalls near working areas
- intersections
- high-activity zones
- areas with fixed equipment
The Mine Health and Safety Council notes that whitewashing should be considered, where reasonably practicable, in high-activity areas, areas where mobile equipment travels, areas with fixed equipment, or areas where a risk assessment shows the need.
This means whitewash is not something to apply randomly. It should be based on the mine’s conditions, procedures and risk assessment.
Why contrast matters
Light reflection is one part of visibility. Contrast is another.
Contrast is the difference between an object and its background. In a dark underground area, some objects may blend into the surrounding rock.
A whitewashed wall creates a lighter background. This may help objects, signs, markings or surface changes stand out more clearly.
For example, a darker pipe, machine or opening may be easier to notice against a lighter sidewall than against a dark rock surface.
That is why whitewash is often discussed together with visibility, reflectance and mine illumination.
Maintenance matters
Whitewash is not a once-off detail.
Underground conditions can affect surface coatings over time. Dust, moisture, equipment movement and daily activity may cause whitewashed areas to become dirty, faded or damaged.
The Mine Health and Safety Council notes that areas should be whitewashed again when the original whitewash becomes faded or when the coating is damaged or removed to the point that it becomes mostly ineffective.
For that reason, whitewashed areas should be checked as part of normal mine maintenance.
A white surface only remains useful if the surface stays visible.
Important note
Every mine is different.
The decision to use whitewash, where to apply it and how often to maintain it should come from the mine’s own procedures, lighting plan and risk assessment.
It is also important not to make exact claims without site data.
For example, whitewash may be used to support light reflection. However, any claim about electricity savings, reduced lighting needs or measured performance should come from the specific mine or a formal assessment.
Final thoughts
Whitewash is a simple idea with a practical purpose.
In underground mines, light-coloured sidewalls are used because they reflect more light than dark surfaces. This is why whitewash is linked to underground visibility planning, reflectance and surface contrast.
It should be understood as part of a wider mine lighting and maintenance approach.
When used in the right areas and maintained according to site procedures, whitewash remains a practical method for improving the way underground surfaces interact with light.
Glossary
Whitewash:
A light-coloured coating used on walls or other surfaces.
Limewash:
A lime-and-water coating often used as a white surface coating.
Reflectance:
The amount of light a surface reflects back.
Illumination:
The amount of light available in an area.
Visual contrast:
The difference between an object and the background around it.
Sidewall:
The side surface of an underground mine tunnel or working area.
Risk assessment:
A process used to identify hazards and decide which controls may be needed.
Recommended Reading – Industry Resource
Mine Health and Safety Council: Proposed Illumination Guidelines for Equipment in the South African Mining Industry
This report explains underground mine illumination challenges and discusses whitewash or light-coloured sidewalls in relation to reflectance and illumination.
From Afri-Lime – Recommended Reading
The Power of Whitewash: A Timeless, Natural Coating with Modern Benefits
Use this as the internal support blog because it explains whitewash as a practical lime-based coating.
