The direct cost of corrosion in South Africa amounts to approximately R150 billion every year, according to the Corrosion Institute of Southern Africa. Furthermore, applying known corrosion control technology could save 25% of those costs — a potential saving of R38 billion annually. Yet most asset managers are still specifying the same anti-corrosion coating for structural steel they used decades ago.
The problem is not always the steel. Often, it is the coating. If your coating cracks under thermal movement, degrades under UV, or demands abrasive blasting before every recoat, you are paying for a maintenance cycle that should not exist. This article explains why silicone is changing that equation — and why it is particularly well suited to Sub-Saharan African conditions.
Why Structural Steel Corrodes Faster in Sub-Saharan Africa
Sub-Saharan Africa presents some of the harshest corrosion conditions on the planet. Coastal zones from Durban to Dar es Salaam expose steel to constant salt-laden air. Industrial regions contribute sulphur dioxide and airborne chemical pollutants. Inland areas experience severe thermal cycling — structures expand and contract sharply as temperatures swing between early morning cold and peak afternoon heat.
UV radiation across southern Africa is among the highest globally. Conventional coating binders that perform adequately in temperate climates degrade far more rapidly here. Chalking, cracking, and adhesion loss accelerate. Once a coating fails at any point, moisture penetrates, and rust creep spreads beneath the surface — undermining adhesion long before visible damage appears.
Moreover, between 25% and 30% of water supply is lost in the supply chain due to corrosion in at least 20 Sub-Saharan African countries, illustrating how far the damage extends beyond visible structural steel. The result, in all cases, is a maintenance cycle that never ends: strip, blast, recoat, repeat.
The Problem With Conventional Anti-Corrosion Coatings
Epoxy coatings dominate the South African market. They offer strong initial adhesion and chemical resistance, and applicators understand them well. However, epoxy has a fundamental limitation in outdoor atmospheric applications: it is rigid.
Steel moves. It expands in heat and contracts in cold. A rigid coating cannot follow that movement indefinitely. Micro-cracks form, moisture enters, and corrosion begins beneath the surface. By the time rust is visible, the damage is already extensive.
Epoxy also requires abrasive blasting for proper surface preparation. In retrofit and maintenance situations — where a structure is already in service — abrasive blasting is disruptive, expensive, and often impractical. It generates significant waste, requires containment, and takes structures offline for extended periods. Zinc-rich primers add further cost and complexity, requiring precise application thickness and additional curing time before topcoating can begin.
For new builds in controlled environments, epoxy remains a capable choice. For maintenance, retrofit, and in-service structures across Sub-Saharan Africa, however, it is frequently the wrong tool.
What Makes Silicone Anti-Corrosion Coating Different
Silicone behaves differently to epoxy at a molecular level. Where epoxy cures rigid, silicone remains flexible after cure. Consequently, this flexibility is not a weakness — it is precisely the property that drives long service life in outdoor atmospheric environments.
SI-COAT 579CM from CSL Silicones is a single-component, moisture-cure, room temperature vulcanising (RTV) silicone coating engineered specifically for corrosion maintenance and retrofit applications. It is available in Sub-Saharan Africa exclusively through Technical Solutions Supplies. Key independently tested performance properties include:
- Elongation at break of 180% — the coating flexes with thermal movement rather than cracking
- 5,000 hours UV accelerated weathering (ASTM G154) with no degradation — tested beyond what most epoxy systems demonstrate
- 3,000-hour salt fog resistance (ASTM B117) — no scribe failure
- 36-month Florida Fence Test with scribe — passed with no rust creep, bleed-through, pinholes, or adhesion loss
- Unlimited recoat window — maintenance overcoating can occur at any point without surface degradation
These results confirm that SI-COAT 579CM is built for the long term — not just the next inspection cycle.
The Retrofit Advantage: No Abrasive Blasting Required
This is where SI-COAT 579CM changes the economics of corrosion maintenance for structural steel across Sub-Saharan Africa.
Conventional coating systems specify abrasive blasting as a minimum surface preparation standard. In retrofit environments, achieving that standard means scaffolding, containment, blast equipment, waste disposal, and significant downtime. For bridges, tanks, and in-service structures, the cost of surface preparation frequently exceeds the cost of the coating itself.
SI-COAT 579CM requires only hand tool cleaning (SSPC-SP2) or power tool cleaning (SSPC-SP3). Loose rust, peeling paint, and surface contamination must be removed, and surfaces must be clean and dry. That is the standard. No abrasive blasting or profiling is required. There is no need for specialist blast crews on site.
Additionally, SI-COAT 579CM is self-priming. A single coat at 8 to 20 mils dry film thickness delivers full corrosion protection. Tack-free time is just 60 minutes at standard conditions, and full cure is achieved within 4 to 6 hours. For areas particularly prone to corrosion — edges, welds, bolts, and pits — spot priming with 5 mils DFT of SI-COAT 579CM before the full coat further extends service life. The same product serves as both primer and finish. No second product required.
Where SI-COAT 579CM Is Specified
SI-COAT 579CM is designed for above-grade atmospheric applications in retrofit and maintenance projects. Therefore, it is well suited to asset managers and engineers working across a broad range of sectors. Typical applications include:
- Structural steel frameworks and support structures
- Road and rail bridges
- Tank exteriors
- Machinery and industrial equipment
- Metal roofs and cladding
- Areas with existing heavy corrosion
It is applied by airless spray for large surface areas, or by brush and roller for smaller sections and spot repairs. Application temperature range is 5°C to 60°C ambient — covering the full range of Sub-Saharan African climatic conditions, from highland cold to coastal heat.
For projects where silicone roof coating or high voltage insulator protection is also required, TSS supplies the full CSL Silicones range across the region.
Frequently Asked Questions About Anti-Corrosion Coating for Structural Steel
What is the best anti-corrosion coating for structural steel?
The best anti-corrosion coating for structural steel depends on the application. For new construction in controlled environments, zinc-rich epoxy systems perform adequately. However, for retrofit, maintenance, and in-service structures in high-UV, coastal, or thermally demanding environments, a flexible silicone coating such as SI-COAT 579CM offers superior long-term performance. Its ability to flex with thermal movement, resist UV degradation, and apply without abrasive blasting makes it the stronger choice for most Sub-Saharan African maintenance applications.
Do you need to sandblast before applying anti-corrosion coating?
Not with SI-COAT 579CM. Most conventional anti-corrosion coatings require abrasive blasting to achieve adequate adhesion. SI-COAT 579CM is self-priming and requires only hand tool or power tool cleaning to SSPC-SP2 or SSPC-SP3 standard. Loose rust and peeling paint must be removed, but abrasive blasting and surface profiling are not required. This significantly reduces preparation time, labour costs, and project disruption on in-service structures.
How long does anti-corrosion coating last on structural steel?
Service life depends on coating type, surface preparation quality, application thickness, and environmental conditions. SI-COAT 579CM has passed a 36-month Florida Fence Test with scribe — one of the most demanding real-world weathering assessments available — with no rust creep, bleed-through, pinholes, or adhesion loss. Its UV accelerated weathering test result of 5,000 hours with no degradation further supports long-term performance in high-UV Sub-Saharan African environments.
Can you apply anti-corrosion coating over existing paint or rust?
SI-COAT 579CM can be applied over existing coatings provided they meet a minimum adhesion rating of 4A or 4B per ASTM D3359. Any paint that is peeling, flaking, or blistering must first be removed. Firmly adhered surface rust that does not lift under hand or power tool cleaning can remain. This makes SI-COAT 579CM particularly well suited to maintenance projects where full coating removal is impractical or cost-prohibitive.
What is the difference between silicone and epoxy anti-corrosion coating?
Epoxy coatings cure rigid and offer strong initial adhesion, but they crack under thermal movement and degrade under prolonged UV exposure in outdoor environments. Silicone coatings cure flexible, maintaining elasticity throughout their service life. SI-COAT 579CM achieves 180% elongation at break, meaning the coating moves with the steel rather than pulling away from it. Silicone also outperforms epoxy in UV resistance and does not require a topcoat to prevent chalking or colour fade. For a broader overview of CSL Silicones product performance, visit the manufacturer’s website directly.
What causes corrosion on steel structures in Sub-Saharan Africa?
Corrosion on structural steel results from the electrochemical reaction between steel, oxygen, and moisture. In Sub-Saharan Africa, several environmental factors accelerate this process significantly. Coastal zones introduce chloride ions from sea air, which penetrate conventional coatings and attack the steel substrate. Industrial areas contribute sulphur dioxide and other airborne pollutants. High UV radiation degrades coating binders, opening pathways for moisture. Extreme thermal cycling causes coatings to fatigue and crack over time. Corrosion is also the cause of 55% of unplanned power outages and adds 10% to the average electricity bill, according to research cited at the Annual Corrosion Control Conference — making it a critical operational concern beyond structural integrity alone.
Protect Your Steel Assets With SI-COAT 579CM
SI-COAT 579CM is available across Sub-Saharan Africa exclusively through Technical Solutions Supplies. Whether you are managing a bridge maintenance programme, protecting industrial equipment, or specifying a retrofit coating for in-service structural steel, our team can advise on the right application approach for your project.
Contact TSS today to discuss your corrosion protection requirements.