In the signage and cladding industry, we heavily depend on the aesthetic. Understandably our client’s main focus is on the “look and feel” of their desired product. The bulk of their attention during design goes into aspects such as the impact of corporate colours, fonts and logos and how these will influence getting the message across. Unfortunately, this often leaves insufficient attention being given to other less noticeable, but equally important factors.
Some of these factors include:
- Protection against corrosion
- Structural integrity
- Designing for production
- Ease of maintenance
- Ease of construction
- Optimization of material
- Electrical connections and wiring
- Ease of access
- Transit optimization
- UV light protection
Let us spend some time on the first of the above-mentioned factors, namely protection against corrosion. The information I will share with you is based on experience we have gained at First African through the years and it remains an informed opinion. Hopefully it will, in future, assist you in making decisions on the corrosion protection of your assets.
What is corrosion?
Corrosion (commonly known as rust) occurs when metal ions (formed from metal oxidation) migrate through an electrolyte to form a corrosion cell. The amount of oxygen, moisture and metal quality has a significant impact on the speed of the process. Corrosion protection is therefore a barrier or protective layer that prevents oxygen and moisture to come into direct contact with structural steel.
Why is corrosion protection relevant within the signage and cladding industry?
Steel is an alloy of mainly iron and carbon, and forms the backbone of most signage and cladding designs. Understanding the life expectancy of the asset and properly protecting it against corrosion, ensures a durable and secure structure that will carry your signage and cladding for years to come. It’s almost like taking calcium to strengthen and protect your bones so it can carry your body into old age. But unfortunately, corrosion protection is not as simple as drinking your milk or taking a vitamin supplement.
Perhaps the biggest challenge posed in the anti-corrosion industry is the multitude of different specifications and methods offered and the fact that the so-called solutions often promise “the same quality and performance as the next but at half the price”. Deciding on a method that will fit both budget and quality requirements can be tricky to say the least.
How do we go about corrosion protection at First African?
We start by understanding exactly what our client’s requirements and expectations are.
After this we draw up a job-specific specification for corrosion protection. We first look at the atmospheric conditions the product will be exposed to. ISO 12944 gives very clear classification categories for this exact purpose.
ISO 12944 focuses on atmospheric corrosivity in typical environments and the expected mass loss/thickness loss after the first 12 months of exposure.
Two of the most commonly used classifications are as follows:
- C5 Marine/industrial: Coastal and offshore areas with very high salinity, this includes areas with humidity, high amounts of rain and pollution
- C3 Inland: Includes urban and industrial areas with moderate Sulphur dioxide pollution and low salinity.
Once the atmospheric conditions and accompanying ISO 12944 classification category are identified, an appropriate type and method of corrosion protection is selected.
Below are the main alternatives we choose from to ensure favourable corrosion protection results:
|Method of protection||Description|
|Resistant Alloys||The most popular corrosion resistant alloys are stainless steel and weathering steel. These alloys however are expensive and seldom a cost-effective solution.|
|Design||A proper design can minimize water pooling, penetration and reduce the risk of corrosion. For best results we still combine this alternative with a protective coating system.|
|Galvanization||The process of galvanization involves coating the surface with an external layer by dipping it in a bath of molten Zinc. The Zinc forms a sacrificial layer which prevents corrosion of the structural steel by acting as an anode that prevents formation of corrosion cells. This means that the damaging oxidation process of rust will be transferred to the zinc layer. This is a very popular anti-corrosion solution, because it has the advantage of covering difficult places where other systems cannot reach i.e. the internal areas of large square and circular hollow sections. The biggest disadvantage is size limitations due to the equipment required and cost.|
|Powder Coating||Powder coating involves the even application of a dry powder to a clean surface. The covered object is then heated, turning the powder into a hard thin film. There are a wide range of powders available including, polyester, nylon, vinyl, epoxy and urethane. The main difference between powder coating and painting is that powder coating is a one step process while painting requires multiple layers in order to create a barrier against corrosion.|
|Paint||Paint is a very cost effective method to protect against corrosion. It is a multi-layered system that collectively forms a barrier against corrosive elements. The most commonly used paint systems in our industry are epoxy, polyurethane and acrylic products. A further advantage of paint is that it can be reapplied and maintained on site. Localised areas of corrosion can also be treated on site to stop the spread thereof.|
|Regular Maintenance||Regular maintenance is an extremely underrated and therefore much underutilised element of corrosion prevention and protection. Regular site inspections with early intervention and maintenance where necessary can drastically lengthen the lifespan of a structure.|
Which protective coating systems do we believe offer the best quality and most cost-effective solution to our clients?
In 2006 we completed a detailed study on the different protective coating systems available in the market. At that stage, paint/protective coatings scored the best results in offering our clients a combination of quality and cost-effectiveness. Based on the results, we decided to start offering this service inhouse without the use of subcontractors. We, therefore, appointed trained applicators and equipped our factory with degreasing and blasting facilities, as well as 4 spray booths and a 120 square meter curing room.
In 2012 we changed our paint supplier to Jotun. Jotun is one of the top coating manufacturers in the world and is the global market leader in the very competitive Marine industry. We continuously monitor the anti-corrosion market for new methods, but to date, we haven’t found a better and more cost-effective solution than paint protection. After almost a decade we still exclusively use Jotun. This quality product, in combination with our ISO 9001 quality system and professional design team, lends us confidence in adhering to all our customer’s protective coating requirements.
In cases where clients prefer other protection options like galvanization or powder coating, we make use of trustworthy subcontractors.
Practical example of how we would protect steel structures to last 15-20 years (high durability) in C5 environment (Coastal):
|Epoxy primer||Jotamastic 90 Aluminum 120 µm|
|Epoxy midcoat||Jotamastic 90 Off-white 100 µm|
|Polyurethane||Hardtop Flexi 80 µm|
|Total system DFT||300 µm|
|To achieve 25+ years durability||System|
|Zinc Epoxy primer||Barrier 60 µm|
|Epoxy Midcoat||Jotamastic 90 Off-white 180 µm|
|Polyurethane||Hardtop Flexi 80 µm|
|Total system DFT||320 µm|
How will I know when my protective coating system is failing?
Things to look out for would be brittleness, flaking, or obvious signs of rust.
An important point to make here is that there is a difference between corrosion protection life span and aesthetic finishing life span. Even the best and most expensive protective system exposed to direct sunlight, harsh weather, and extreme temperatures will show deterioration and fading over time. Clients need to remember that fading and discoloration over time do not necessarily mean the protective barrier is failing.
In an industry where aesthetic appeal is crucial, our advice to clients would be to allow for repainting (depending on location and severity of the environment) every 5-10 years. This will not only improve the visual appearance but also increase the lifespan of the corrosion protection.
Corrosion and protection against it is not a new topic in our industry, but it is definitely one to take careful note of.
Hopefully, the information above will serve as a reminder to double-check that your chosen signage or cladding supplier does not cut corners on the protection of the structural backbone of your project. If you have any further questions or need guidance with your next design or project, please do not hesitate to contact us.