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2. General guidelines for different types of substrates
New or old steel without galvanising
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| Application methods
1. General rules for ZINGA
The layer thickness of the first coat of ZINGA must not be too high: 40µm is perfect. If the layer is too thick, then the solvents cannot evaporate sufficiently, which causes solvent retention and there is also the risk of formation of pinholes.
The following layers, when applied by an airless spraying technique, can have a thickness of 60 to 80µm. The total layer thickness that is prescribed will depend on the used coating system (ZINGA is a unique system, ZINGA in a duplex system with topcoats, ZINGA on top of hot-dip galvanisation,...).
Theoretical spreading rate:
with 1Kg of ZINGA you can cover 3.54m² at a layer thickness of 40µm.
ZINGA is touch-dry and dust-free in about 10 minutes, depending on the atmospheric conditions and the drying process. It is mechanically cured after approximately 48 hours.
ZINGA is a coating that is best applied in two layers. A new coating of ZINGA can be applied after one hour. In a duplex system, topcoats can be applied after 4 to 24 hours, depending on the drying process.
For the application of ZINGA there are only very few restrictions.
A few things that do need your attention:
In any environment invisible air contamination could be present. When the ZINGA is applied in a workshop, you must make sure that there is no diesel or silicone vapour in the air. When ZINGA is applied in a maritime environment, there can be a lot of salt in the air that contaminates the surface during application.
ZINGA can be applied in an atmosphere with high relative humidity. However, you must make sure that the ZINGA is applied at a temperature that is at least 3°C above the dew point.
Temperature and air circulation can strongly influence the drying and the polymerisation of the ZINGA coating.
2. General guidelines for different
types of applications
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| Lifetime and maintenance
1. Life expectancy
ZINGA as a unique system
This diagram is based on the BBA certificate nr. 94/3042, issued by the British Board of Agrément, UK, that ZINGA has obtained. Concerning the durability of ZINGA is stated that ZINGA with a layer thickness of 60µm will remain effective:
- in excess of 20 years in interior conditions
- 20 years in rural conditions
- 12 years in inland industrial conditions
- 10 years in polluted coastal conditions
However, in view of our own experiences, we can confirm that figures on this diagram indicate an absolute minimum lifetime of ZINGA. In practice, ZINGA has a much better performance.
We refer to the application of ZINGA as a unique system on the Kalvoya Bridge in Norway in 1985. In 2000, 15 years after the application, the bridge was inspected and the layer thickness was measured. This report is very important because it gives us an idea of the estimated lifetime of ZINGA. (view)
Also take a look at the test report from the South African Bureau of Standards, dated 04/04/96. A salt spray test (400 hours) was performed on ZINGA in comparison to hot-dip, after which the loss in weight of the galvanising coatings was measured. (view)
As you can see, the table stops at 150µm. That is because 150µm is the absolute maximum total layer thickness that we would prescribe for ZINGA as a unique system. Applying more than 150µm would not improve the efficiency of the cathodic protection any more.
ZINGA in a duplex system
Lifetime duplex system = (1.8 to 2.5 ) x (lifetime ZINGA + lifetime paint)
The recommended layer thickness of ZINGA in a duplex system is 60µm. In an industrial environment, the lifetime of the ZINGA will be at least 12 years. If the expected lifetime of the topcoat is for instance 4 years, then the total expected lifetime of the duplex system will be 29 to 40 years.
2. Maintenance on ZINGA as a unique system
Periodic inspection, touch-ups and recharging
Maintenance should be conducted before the steel substrate has become exposed. Periodic inspection to determine the thickness of the ZINGA coating is of prime importance, especially in a very aggressive industrial or martime environment.
In case there has been mechanical damage, the ZINGA coating can be repaired with local touch-ups. Welding is possible on top of ZINGA. After the welding, the welding seam has to be cleaned and roughened. Then a new application of ZINGA can be done locally, on top of the welding. Keep in mind that zinc is too soft to be included in high performance welding.
In case 5 to 10 % of the total surface is corroded, a new ZINGA application on the total surface will be necessary. The ZINGA coating can be maintained on site. We call this recharging. This way the ZINGA can infinitely protect the steel substrate.
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